+)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))), * MCP Application Notes: * * * * 1. Character(s) preceded & followed by these symbols (. -) or (+ ,) * * are super- or subscripted, respectively. * * EXAMPLES: 42m.3- = 42 cubic meters * * CO+2, = carbon dioxide * * * * 2. All table notes (letters and numbers) have been enclosed in square* * brackets in both the table and below the table. The same is * * true for footnotes. * .))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))-

ACI 547R-79 (Revised 1983) (Reapproved 1987) (Reapproved 1997)

Refractory Concrete: Abstract of State-of-the-Art Report

Reported by ACI Committee 547

I. Leon Glassgold, Chairman; Timothy J. Fowler, Editor; JosephHeneghan, Secretary; Henry E. Anthonis; Seymour A. Bortz; WilliamE. Boyd; Khushi R. Chugh; Sidney Diamond; William A. Drudy;Joseph E. Kopanda; Svein Kopfelt; David R. Lankard; William S.Netter; Richard C. Olson; William C. Raisbeck; Richard L. Shultz.

Refractory concretes are currently used in a wide variety ofindustrial applications where pyroprocessing and/or thermalcontainment is required. The service demands of theseapplications are becoming increasingly severe and this, combinedwith the constant demand for refractories with enhanced servicelife and more efficient means of installation, has resulted in anever expanding refractory concrete technology, ACI Committee 547has prepared this state-of-the-art report in order to meet theneed for a better understanding of this relatively newtechnology.

The report presents background information and perspective onthe history and current status of the technology. Composition andproportioning methods are discussed together with a detailedreview of the constituent ingredients. Emphasis is placed onproper procedures for the installation, curing, drying, andfiring. The physical and engineering properties of both normalweight and lightweight refractory concretes are reported, as arestate-of-the-art construction details and repair/maintenancetechniques. Also included is an in-depth review of a wide varietyof applications together with the committee's assessment offuture needs and developments.

Keywords: abrasion; accelerating agents; admixtures; aggregates:aluminate cement and concretes; anchorage (structural);cement-aggregate reactions; chemical analysis; construction;corrosion; curing; drying; failure mechanisms; formwork(construction); hydration; insulating concretes; kilns;lightweight concretes; mechanical properties; mix proportioning;packaged concrete: physical properties; placing; pumped concrete;quality control; refractories; refractory concretes: reinforcingmaterials; repairs; research; shotcrete; spalling; structuralanalysis; temperature; thermal properties; water; welded wirefabric. Copyright (c) 1979, American Concrete Institute

All rights reserved including rights of reproduction and use inany form or by any means, including the making of copies by anyphoto process, or by any electronic or mechanical device, printedor written or oral, or recording for sound or visual reproductionor for use in any knowledge or retrieval system or device, unless

permission in writing is obtained from the copyright proprietors.

ACI Committee Reports, Guides, Standard Practices, andCommentaries are intended for guidance in designing, planning,executing, or inspecting construction and in preparingspecifications. Reference to these documents shall not be made inthe Project Documents. If items found in these documents aredesired to be part of the Project Documents they should bephrased in mandatory language and incorporated into the ProjectDocuments. Discussion of this committee report may be submitted inaccordance with general requirements of the ACI PublicationPolicy to ACI Headquarters, P.O. Box 19150, Detroit, Michigan48219. Closing date for submission of discussion is November 1,1979.

This abstract first appeared in Concrete International: Design& Construction, V. 1, No. 5, May 1979, pp. 62-77. The full reportis available as a separate publication in 8¼ x 11 in., papercover format, consisting of 224 pages. Contents listed on thispage represent only the sections of the report covered in thisabstract.

Contents of summary

Chapter 1--Introduction

1.1--Objective of report 1.2--Scope of report 1.3--Nomenclature 1.6--Non-hydraulic setting refractories

Chapter 2--Criteria for refractory concrete selection lightweight

2.1--Introduction 2.2--Castables and field mixes 2.5--Load bearing considerations 2.7--Corrosion influences 2.10--Abrasion and erosion resistance

Chapter 3--Constituent ingredients 3.2--Binders 3.3--Aggregates 3.4--Effects of extraneous materials

Chapter 4--Composition and proportioning

4.1--Introduction 4.3--Field mixes 4.4--Water content

Chapter 5--Installation

5.1--Introduction

5.2--Casting 5.3--Shotcreting 5.4--Pumping and extruding 5.5--Pneumatic gun casting 5.8--Finishing

Chapter 6--Curing, drying, firing

6.1--Introduction 6.2--Bond mechanisms 6.3--Curing 6.4--Drying 6.5--Firing

Chapter 7--Properties of normal weight refractory concretes

7.1--Introduction 7.2--Maximum service temperature 7.4--Shrinkage and expansion 7.5--Strength 7.6--Thermal conductivity 7.10--Specific heat

Chapter 8--Properties of lightweight refractory concretes

8.1--Introduction 8.4--Shrinkage and expansion 8.5--Strength 8.6--Thermal conductivity 8.10--Specific heat

Chapter 9--Construction details

9.1--Introduction 9.2--Support structure 9.3--Forms 9.4--Anchors 9.5--Reinforcement and metal embedment 9.6--Joints Chapter 10--Repair

10.1--Introduction 10.2--Failure mechanisms 10.3--Surface preparation 10.4--Anchoring and bonding 10.5--Repair materials 10.6--Repair techniques

Chapter 11--Applications

11.1--Introduction

Chapter 12--New developments and future use of refractory concrete

12.1--Introduction 12.2--New developments 12.3--Research requirements

Chapter 1--Introduction

1.1 Objective of report

The objective of this report is to provide a source ofinformation on the many facets of refractory concrete technology.The report is intended as a unified and objective source ofinformation to aid the engineer or consumer in categorizing andevaluating monolithic refractory concrete technology and the manymaterials and processes available today. It is not intended to bea specification or standard, and should not be quoted or used forthat purpose.

1.2 Scope of report

Refractory concrete is concrete suitable for use attemperatures up to about 3400 F (1870 C). It consists of a gradedrefractory aggregate bound by a suitable cementing medium. Thisreport is concerned with refractory concrete in which the bindingagent is a hydraulic cement, and does not consider concreteswhich use waterglass (sodium silicate), phosphoric acid, orphosphates as a principal cementing agent. It covers all facetsof refractory concrete installation and use, including theproperties of individual ingredients and concretes, placingtechniques, methods of curing and firing, repair procedures,construction details, and current and future applications.

1.3 Nomenclature The following definitions[1,2] are used in this report:

ACID REFRACTORIES--Refractories containing a substantial amountof silica that may react chemically with basic refractories,basic slags, or basic fluxes at high temperatures.

APPARENT POROSITY (ASTM C20)--The relationship of the volume ofthe open pores in a refractory specimen to its exterior volume,expressed as a percentage.

BASIC REFRACTORIES--Refractories whose major constituent is lime,magnesia, or both, and which may react chemically with acidrefractories, acid slags, or acid fluxes at high temperatures.(Commercial use of this term also includes refractories made ofchrome ore or combinations of chrome are and dead burnedmagnesite).

CALCIUM ALUMINATE CEMENT--The product obtained by pulverizingclinker which consists of hydraulic calcium aluminates formed byfusing or sintering a suitably proportioned mixture of aluminousand calcareous materials.

CASTABLE REFRACTORY--A proprietary packaged dry mixture ofhydraulic cement and specially selected and proportionedrefractory aggregates which, when mixed with water, will producerefractory concrete or mortar.

CERAMIC BOND--The high strength bond which is developed betweenmaterials, such as calcium aluminate cement and refractoryaggregates, as a result of thermochemical reactions which occurwhen the materials are subjected to elevated temperature.

EXPLOSIVE SPALLING--A sudden spalling which occurs as the resultof a build-up of steam pressure caused by too rapid heating onfirst firing.

GROG--Burned refractory material, usually calcined clay orcrushed brick bats.

HEAT RESISTANT CONCRETE--Any concrete which will not disintegratewhen exposed to constant or cyclical heating at any temperaturebelow which a ceramic bond is formed.

HIGH ALUMINA CEMENT--See calcium aluminate cement.

NEUTRAL REFRACTORIES--Refractories that are resistant to chemicalattack by both acid and basic slags, refractories, or fluxes athigh temperatures.

REFRACTORY AGGREGATE--Materials having refractory propertieswhich form a refractory body when bound into a conglomerate massby a matrix. REFRACTORY CONCRETE--Concrete which is suitable for use at hightemperatures and contains hydraulic cement as the binding agent.

SOFTENING TEMPERATURE--The temperature at which a refractorymaterial begins to undergo permanent deformation under specifiedconditions. This term is more appropriately applied to glassesthan to refractory concretes.

THERMAL SHOCK--The exposure of a material or body to a rapidchange in temperature which may have a deleterious effect.

1.6 Non-hydraulic setting refractories[5]

The following discussion, while not pertinent to the main themeof the report, will be of some interest and use to the reader.

1.6.1 Refractory brick--High quality brick, known as firebrick,with unique chemical and physical properties is obtained byblending different types of clay and other ingredients and byvarying both the method of processing and the burningtemperatures. In addition to the many varieties of fireclaybrick, high alumina, insulating, silica, fused aggregate, andbasic firebrick have been developed. Refractory brick remains amajor construction material for applications in which heatcontainment and control is necessary and in many instances, isthe only satisfactory solution to a specific problem.

Brick has a number of disadvantages when compared to monolithicrefractories. These disadvantages include multiple joints,complicated anchoring, higher placement costs, more difficultrepair procedures, the need to maintain expensive inventories ofspecial or scarce items, a certain inflexibility in structuraldesign, and higher fuel requirements during manufacture.

1.6.2 Plastics and ramming mixes--Plastic refractories andramming mixes are refractories which are tamped or rammed inplace and are used for monolithic construction, for repairpurposes, and for molding special shapes. These materials findextensive use in industry. They usually employ a clay, alumina,magnesite, chrome, silicon carbide, or graphite base, and are

blended with a binder. Heat setting mixes are likely to containfireclay or phosphoric acid as a binder. Air or cold-settingmixes generally contain fireclay and sodium silicate as thebinder. Compared to ramming mixes, plastic refractories havehigher moisture contents and therefore, higher plasticity.

Plastics are generally placed without use of forms. With theexception of some specialized tabular alumina castables, plasticshave a somewhat higher service limit than castable refractories.Their main disadvantages are greater shrinkage and crackdevelopment. Except for phosphate bonded materials cured above600 F (315 C), plastics generally have lower cold and hotstrengths than refractory concretes. In addition, plastics tendto have a relatively low strength zone on the cool side of thelining.

Ramming mixes usually have higher density and less shrinkagethan plastic refractories. With their low water content, theymust be forced into place and require strong well-braced forms.Some of the dryer medium grind ramming mixes are suitable forgunning, and are used for patching and maintenance materials.

1.6.4 Gunning mixes other than refractory concretes [12,13]--Asused in this section, the term "gunning mixes" does not refer torefractory concrete and should not be confused with gunnedrefractory materials which produce refractory concrete. Gunningmixes are mixtures of non-hydraulic setting ingredients which areinstalled hot or cold, usually by the shotcrete method.

Gunning mixes generally have low rebound loss, arepredominately used for patching or resurfacing brick or otherrefractories, have a strong internal bond, and exhibit excellentadhesion or bond to the existing refractory lining. They findextensive use in basic oxygen, electric arc and open hearthfurnaces, among other applications.

Chapter 2--Criteria for refractory concrete selection

2.1 Introduction

Refractory concrete is usually made with high alumina cement.It is not generally used as a structural material and its primarypurpose is as a protective lining for steel, concrete or brickstructures. It is considered a consumable material requiringreplacement after an appropriate service life.

Some of the destructive forces that refractory concreteswithstand are abrasion, erosion, physical abuse, hightemperatures, thermal shock, hot and molten metals, clinker,slag, alkalies, mild acid or acid fumes, expansion, contraction,carbon monoxide, and flame impingement.

Refractory concretes are categorized as either normal weight orlightweight. The former are also referred to as "heavy refractoryconcretes" and the latter are often called "insulating refractoryconcretes." Table 2.1a shows the characteristics of a typicalrange of normal weight refractory concretes; Table 2.1b shows thecharacteristics of lightweight refractory concretes.

Table 2.1a - Characteristics of normal weight refractory concretes TABULAR Al+2,O+3, COARSE COARSE HIGH PURITY BINDER GENERAL HIGH EROSION/ HIGH HIGH LOW IRONPRODUCT HIGH PURPOSE STRENGTH ABRASION 2800 F HIGH STRENGTH STRENGTH HIGH DESCRIPTION STRENGTH 3000E 2800F 2800 F GUN RESISTANT STEEL MILL STANDARD STRENGTH 2350 F 2600 F STRENGTH )))))))))) )))))))) ))))) ))))) )))))))))) )))))))))) )))))))))) )))))))) ))))))))) )))))) )))))) )))))))) Recommended Service Temperature max., Deg F. * 3400 * 3000 * 2800 * 2800 * 2400 * 2800 * 2600 * 2500 * 2350 * 2600 * 2600 ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))ASTM Class (C-401) * G * E * - * - * B * D * C * C * B * C * C ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Water required for Mixing, * * * * * * * * * * * Percent by Weight * 8-11 * 8-12 * 10-12 * (3) * 10-12.5 * 10-13 * 15-21 * 14.0-15.5 * 11-14 * 3.5-11 * 14-16 ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Material Required (1) * 160-165 * 140-145 * 129-133 * 129-133 * 125-130 * 125-131 * 108-114 * 120-124 * 126-130 * 137-142 * 118-120 lbs. per cu. ft., lbs. per bag * * * * * * * * * * * ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Method of application (2) * C-T-S * C-T-S-E * C-T * S * C-T-S * C-E * C-T-E * C-T-S-E * C * C * C-T-S-E ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Bulk Density, 220 F * 105 178 * 139 147 * 131 138 * 130 136 * 135 143 * 134 136 * 112 121 * 126 133 * 131 133 * 144 146 * 124 131 Heated to 1000 F * 159 169 * 138 146 * 128 134 * 127 133 * 129 134 * 132 134 * 108 117 * 120 125 * 126 129 * - * 122 124 temperature of: 1500 F * 161 174 * 138 146 * 128 132 * 126 133 * 129 134 * 130 133 * 108 114 * 120 122 * 124 129 * 138 140 * 121 122 then cooled 2000 F * 161 174 * 137 146 * 130 135 * 127 133 * 127 135 * 130 133 * 101 115 * 120 123 * 124 128 * 140 141 * 120 121 pcf 2550 F * 165 176 * 139 150 * 123 128 * 127 130 * - * 124 132 * 111 114 * - * - * 133 138 * 121 123 2732 F * 160 169 * 138 146 * 123 127 * 128 135 * - * 128 138 * - * - * - * - * - 3000 F * 165 167 * 136 149 * - * - * - * * - * - * - * - * - ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Total Linear Change % Heated 220 F * 0.0 to -0.5 * -0.1 to -0.6 * -0.1 to -0.4 * -0.2 to -0.6 * -0.2 to -0.7 * -0.3 to -0.4 * -0.1 to -0.5 * -0.1 to-0.5 * -0.1 to -0.5 * 0.0 to -0.3 * -0.2 to -0.4 to temp. of: then cooled 1000 F * -0.1 to -0.5 * -0.1 to -0.6 * -0.2 to -0.3 * -0.2 to -0.5 * -0.2 to -0.6 * -0.3 to -0.4 * -0.1 to -0.6 * -0.2 to-0.5 * -0.3 to -0.6 * - * -0.4 to -0.5 (Note: Linear change 1550 F * -0.1 to -0.5 * -0.2 to -0.6 * -0.1 to -0.5 * -0.1 to -0.5 * -0.2 to -0.6 * -0.2 to -0.4 * -0.2 to -0.5 * -0.1 to-0.7 * -0.4 to -0.6 * 0.0 to -0.3 * -0.4 to -0.5 figures are "TOTAL" 2000 F * -0.1 to -0.3 * -0.2 to -0.7 * -0.3 to -0.7 * -0.1 to -0.9 * -0.1 to -0.6 * -0.2 to -0.5 * -0.4 to -0.8 * -0.1 to-0.9 * -0.3 to -0.5 * -0.1 to -0.5 * -0.5 to -0.7 in all cases and include 2550 F * -0.4 to -1.3 * -0.5 to -1.1 * -0.8 to +1.3 * -0.5 to +0.2 * - * +1.7 to +2.2 * -1.2 to +1.3 * - * - * -0.1 to +1.7 * -0.1 to +0.5 percent of drying 2732 F * -0.7 to -1.4 * -0.2 to +0.3 * -0.5 to +1.0 * -0.8 to +0.8 * - * +1.3 to +2.4 * - * - * - * - * - shrinkage occurring 3000 F * -0.6 to -1.1 * +0.1 to +0.7 * - * - * - * - * - * - * - * - * - in conversion from * * * * * * * * * * * wet "as cast" * * * * * * * * * * * to "as dried" state) * * * * * * * * * * * ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Modulus of Rupture, psi 220 F * 1600 - 2590 * 450 - 840 * 360 - 600 * 400 - 840 * 1260 - 2000 * 445 - 745 * 310 - 520 * 820 - 1170 * 975 - 1030 * 810 - 1015 * 1020 - 1250 Heated to 1000 F * 1820 - 2320 * 350 - 570 * 370 - 650 * 320 - 680 * 945 - 1240 * 175 - 310 * 200 - 270 * 300 - 590 * 535 - 710 * - * 395 - 440 temperature of: 1550 F * 1450 - 2120 * 290 - 580 * 230 - 680 * 530 - 840 * 1020 - 1865 * 145 - 295 * 150 - 200 * 300 - 560 * 400 - 560 * 300 - 415 * 370 - 570 then cooled 2000 F * 930 - 1400 * 340 - 590 * 390 - 780 * 500 - 970 * 1000 - 1385 * 145 - 270 * 130 - 240 * 300 - 460 * 405 - 465 * 310 - 395 * 385 - 605 2550 F * 1280 - 2615 * 820 - 2050 * 1000 - 2450 * 1300 - 3030 * - * 1245 - 2605 * 820 - 1780 * - * - * 520 - 910 * 1370 - 2390 2732 F * 1290 - 2707 * 1260 - 2400 * 1110 - 2260 * 2290 - 3740 * - * 2095 - 2930 * - * - * - * - * - 3000 F * 750 - 1280 * 1685 - 4620 * - * - * - * - * - * - * - * - * - ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))) Cold Crushing Strength, 220 F * 5180 - 10230 * 1030 - 2160 * 1420 - 3780 * 1190 - 2620 * 4510 - 7910 * 1280 - 3145 * 990 - 1570 * 2410 - 3800 * 3450 - 3870 * 2150 - 3580 * 3075 - 5470 psi 1000 F * 8170 - 9160 * 1070 - 2250 * 1490 - 2950 * 1400 - 3000 * 3810 - 6480 * 645 - 1400 * 685 - 1030 * 1470 - 2210 * 1800 - 2290 * - * 2955 - 3795 Heated to 1550 F * 7280 - 9895 * 950 - 2250 * 1110 - 2770 * 1690 - 3340 * 4410 - 7115 * 540 - 1260 * 630 - 840 * 1530 - 2090 * 1775 - 2325 * 1450 - 1590 * 2425 - 2845 temperature of: 2000 F * 3036 - 10000 * 980 - 2050 * 1330 - 2920 * 1160 - 3105 * 3620 - 5375 * 560 - 915 * 640 - 850 * 1450 - 2070 * 1480 - 2225 * 1050 - 1340 * 1500 - 2105 then cooled 2550 F * 6180 - 11000 * 3280 - 4640 * 3200 - 7930 * 4250 - 11390 * - * 3021 - 3765 * 3200 - 5490 * - * - * 1470 - 2280 * 3735 - 6970 2732 F * 4330 - 10115 * 4280 - 5620 * 5280 - 12100 * 7140 - 13175 * - * - * - * - * - * - * - 3000 F * 3320 - 5325 * 5870 - 10000 * - * - * - * - * - * - * - * - * - ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Thermal Conductivity 500 F * 9.87 * 6.47 * 5.35 * 4.60 * 5.24 * 4.78 * 4.00 * 4.10 * 4.48 * 7.25 * 4.60 Btu/in/hr-sq.ft.-Deg F 1000 F * 9.46 * 6.15 * 5.35 * 5.00 * 5.10 * 5.12 * 4.33 * 4.48 * 4.85 * 7.40 * 5.00 at Mean 1500 F * 9.36 * 5.80 * 5.40 * 5.40 * 5.10 * 5.50 * 4.68 * 4.85 * 5.30 * 7.65 * 5.40 Temperature of: 2000 F * 9.57 * 5.72 * 5.65 * 5.80 * 5.18 * 5.88 * 5.02 * 5.19 * 5.73 * 7.85 * 5.80 ))))))))))))))))))))))))))))))))))))3)))))))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3)))))))))))))))3))))))))))))))))Chemical Analysis percent * * * * * * * * * * * SiO+2, * 0.03 * 29.73 * 47.58 * 47.31 * 32.06 * 43.19 * 43.71 * 44.35 * 34.64 * 4.18 * 46.08

Al+2,O+3,, TiO+2, * 93.65 * 65.16 * 48.31 * 46.73 * 59.23 * 46.70 * 40.03 * 38.68 * 57.69 * 55.66 * 31.86 Fe+2,O+3,, FeO * 0.27 * 1.15 * 1.47 * 1.37 * 0.91 * 3.05 * 4.22 * 4.78 * 1.30 * 1.19 * 2.57 CaO, MgO * 5.52 * 2.48 * 1.47 * 3.25 * 6.89 * 6.09 * 9.03 * 11.31 * 5.63 * 2.96 * 17.08 Alkalies * 0.11 * 0.39 * 0.82 * 0.84 * 0.59 * 0.69 * 1.22 * 0.74 * 0.42 * 0.45 * 1.14 Ignition Loss * 0.30 * 0.66 * 0.15 * 0.47 * - * Trace * 1.14 * 0.11 * 0.27 * 0.11 * 0.67 ))))))))))))))))))))))))))))))))))))2)))))))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2)))))))))))))))2))))))))))))))))

Note: All measurements except thermal conductivity taken at room temperature.

SI conversion factorsDeg F = 1.8 C + 321 pcf = 16.02 kg/m.3-1 lb = 0.4536 kg1 psi = 0.006895 MPa1 Btu-in./hr-sq ft - deg F

TABLE 2.1b - Characteristics of lightweight insulating refractory concretes VERMICULITE COMMERCIAL HIGH LIGHT- LIGHT- BASE VERY PRODUCT ALUMINA GENERAL WEIGHT WEIGHT LIGHT- DESCRIPTION * LOW IRON * PURPOSE * 2250 F * 1800 F * WEIGHT ))))))))))) * )))))))) * ))))))) * )))))) * )))))) * )))))) Recommended Service * * * * *Temp. max., Deg. F * 3000 * 2500 * 2250 * **1800 * 1600))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))ASTM Class (C 401) * Q * Q * P&O * N * Special ))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Water required for Mixing, * * * * *Percent by Weight * 24-27.5 * 38-47 * 40-47 * 46-55 * 176))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Materials Required, * * * * * lbs. per cu. ft. * 87-92 * 80-85 * 48-50 * 46-48 * 24 ))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Method of Application* * C-S-E * C-T-S-E * C-T-S-E * C-S-E * C-T-E))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Bulk Density * * * * * lbs. per cu. ft., 220 F * 92-96 * 86-90 * 51-53 * 48-54 * 21-25 Heated to 1500 F * 90-91 * 80-83 * 47-48 * 47-54 * 20-25 Temp. of: 2000 F * 89-92 * 80-84 * 48-49 * 46-52 * - the cooled: 2250 F * 90-91 * 80-82 * 47-40 * - * - 2550 F * 86-92 * - * - * - * - 2910 F * 88-93 * - * - * - * - ))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Total Linear Change, * * * * *Percent 220 F * -0.2 to -0.3 * -0.2 to -0.6 * -0.3 to -0.4 * -0.1 to -0.4 * -0.2 to -0.4Heated to 1500 F * -0.4 to -0.7 * -0.4 to -0.8 * -0.3 to -0.9 * -1.7 to -2.0 * -0.9 to -2.0Temp. of: 2000 F * -0.6 to -0.8 * -0.3 to -0.8 * -0.3 to -1.1 * -0.8 to -1.3 * -the cooled 2250 F * -0.4 to -0.6 * -0.2 to -0.4 * -0.4 to -1.4 * - * - 2550 F * -0.6 to +0.8 * - * - * - * - 2910 F * -0.2 to +0.2 * - * - * - * -))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Modulus of Rupture, * * * * * psi 220 F * 265-360 * 190-350 * 100-150 * 200-420 * 15-55 Heated to 1500 F * 205-225 * 140-230 * 70-90 * 105-140 * 15-50 Temp. of: 2000 F * 280-315 * 120-250 * 75-115 * 100-205 * - then cooled 2250 F * 625-640 * 155-315 * 160-170 * - * - 2550 F * 950-955 * - * - * - * - 2910 F * 1755-1835 * - * - * - * - ))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Cold Crushing Strength, * * * * *psi 220 F * 615-685 * 360-1040 * 290-450 * 390-750 * 30-70Heated to 1500 F * 550-610 * 830-710 * 160-290 * 295-405 * 20-80Temp. of: 2000 F * 450-545 * 460-800 * 130-220 * 200-285 * -then cooled 2250 F * 800-880 * 500-810 * 270-330 * - * - 2550 F * 1265-1415 * - * - * - * - 2910 F * 3535-4100 * - * - * - * - * * * * *))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Chemical Analysis, percent * * * * * * * * * * SiO+2, * 36.52 * 40.08 * 37.38 * 43.17 * - Al+2,O+3,, TiO+2, * 54.63 * 38.13 * 34.79 * 17.68 * - Fe+2,O+3,, FeO * 1.38 * 5.31 * 6.63 * 3.11 * - CaO, MgO * 4.56 * 13.53 * 17.68 * 31.34 * - Alkalies * 1.11 * 1.66 * 1.88 * 2.05 * - Ignition Loss * 1.90 * 1.20 * 1.45 * 2.40 * -

SO+3, * - * - * - * - * - ))))))))))))))))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))))3))))))))))))Thermal Conductivity (k), * * * * * Btu/Hr./Sq. Ft./F./In, * * * * * At Mean * * * * * Temp. of: 500 F * 2.88 * 2.58 * 1.66 * 1.40 * 0.87 1000 F * 3.19 * 2.86 * 1.98 * 1.71 * 1.15 1500 F * 3.50 * 3.14 * 2.31 * 2.01 * 1.43 2000 F * 3.82 * 3.42 * 2.63 * - * - ))))))))))))))))))))))))))))2))))))))))))))2))))))))))))))2))))))))))))))2))))))))))))))2))))))))))))

*Casting; T-Troweling; S-Shotcreting; E-Extruding. All measurements exceptthermal conductivity taken at room temperature.**2000 F (For back-up material)

SI conversion factorsDeg F = 1.8 C + 321 pcf = 16.02 kg/m.3-1 lb = 0.4536 kg1 psi = 0.006895 MPa1 Btu-in./hr-sq ft - deg F

Refractory concretes are usually prepared at the job site frommaterials supplied to the user in either of two ways: (1prepackaged so-called "refractory castables;" (2) field mixes.

Refractory castables are plant packaged mixes composed ofingredients that are weighed, blended and usually bagged inconvenient sizes for shipping and handling. They require onlymixing with water on the job to produce refractory concrete.Field mixes are made from material components which areproportioned and mixed on the site just prior to the addition ofwater.

2.5 Load bearing considerations Most application designs of refractory concrete consider thatthere is a thermal gradient through the material with heatconducted from the hot face to the cold face. A cross section ofthe refractory will usually have a layer at the hot face that hasa cermaic bond, an intermediate section with a weaker combinationof ceramic and a partial hydraulic bond, and a cold face sectionthat retains most of its hydraulic bond. Refractory concretelinigs in this type of situation are usually well anchored andself-supporting.

Castables containing high proportions of coarse aggregatesproduce refractory concrete with good load bearingcharacterisitcs. Certain types of refractory concrete tend tohave low strengths in the intermediate temperature zones [1500-2250 F (820-1230 C)] and should not be subjected to excessivemechanical abuse or dead load. Generally, lightweight concretesdesigned for insulating purposes should not be subjected toimpact, heavy loads, abrasion, erosion or other physical abuse.Normally, both the strength and the resistance to destructiveforces decline as the bulk density of the refractory concretedecreases. There are a number of special refractory castables availablewhich have better than average load-bearing capabilities andwithstand abrasion or erosion much better than the standardtypes.

2.7 Corrosion influences

High temperature in combination with a corrosive environmentcan have a serious deleterious effect on both the concrete andthe backup steel structure. Generally, the higher density, higherpurity refractory concretes have better corrosion resistance thanthe lower density, lower purity types.

Alkalies can effect the service life of refractory concretes.The furnace charge can give off both alkalies (K+2,O) and thefuel sulfur compounds (SO+2,) as vapors. These can penetrate intothe pores of the refractory concrete and react; their reactionproducts cool, solidify, and expand, sometimes causing the hotface of the refractory to peel or shear away.

In certain applications, the refractory concrete is subjectedto highly reducing conditions. Low-iron refractory concretesshould be used for this type of application.

2.10 Abrasion and erosion resistance

Abrasion and erosion begin with the wearing away of the weakestmatrix constitutent, binder, leaving the coarse or hard aggregateto eventually fall away. A hard aggregate, a high modulus ofrupture, and high compressive strength at the hot face arenecessary for good abrasion and erosion resistance in refractoryconcretes.

Chapter 3--Constituent ingredients

3.2 Binders

The binders principally used in refractory concretes arecalcium aluminate cements. However, ASTM-type portland cementscan be used in some refractory applications up to an approximatemaximum of 2000 F (1090 C) with selected aggregates, if specialprecautions are taken to ensure a sound refractory concrete.Cyclic heating and cooling tends to disrupt portland cementconcretes and adding a fine siliceous material to react with thecalcium hydroxide, formed during hydration, is helpful inalleviating the problem.

Calcium aluminate (high alumina) cements are commerciallyavailable hydraulic binders. They are specifically designed foruse in monolithic refractory concrete construction. They aregenerally classified under three basic categories: Low Purity,Intermediate Purity, and High Purity. This is a relativeclassification scheme and is based primarily on the total ironcontent of the cement.

Binder selection is primarily based on the service temperaturedesired for the refractory concrete. Maximum service temperaturesare extended with increasing Al+2,O+3, and decreasing ironcontents. Lower iron content binders are also beneficial inreducing carbon monoxide (CO) disintegration of concrete (Section2.7).

3.3 Aggregates

The maximum service temperatures of selected aggregates mixedwith appropriate calcium aluminate cements are listed in Table3.3a.

TABLE 3.3a - Maximum service temperature of selected aggregates mixed withcalcium aluminate cementsunder optimum conditions4444444444444444444444444444444444444444444444444444444444444444444444444444444444444444444 Maximum temperature Aggregate Remarks Deg C Deg F )))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))Alumina, tabular Refractory, abrasion 1870 3400 resistant Dolomitic limestone Abrasion and corrosion 500 930 (gravel) resistant Fireclay, expanded Insulating, abrasion and 1640 2980 corrosion resistant Fireclay brick, Abrasion and corrosion 1600 2910 crushed resistant Flint fireclay, 1650 3000 calcined Kaolin, calcined Abrasion and corrosion 1650 3000 resistant Mullite 1650 3000 Perlite Insulating 1340 2450 Sand (Silica content less 300 570 than 90 percent not recommended Abrasion and corrosion resistant Slag, blast furnace Abrasion resistant 540 1000 (air cooled) Slag, blast furnace Insulating, abrasion and 1200 2190 (granulated) corrosion resistant Trap rock, diabase (Basic Igneous Rock- 1000 1830 Minimal Quartz) Abrasion and corrosion resistant Vermiculite Insulating 1100 2010 )))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))

These maximum temperatures are based on optimum conditions ofbinder and aggregate. Thermal properties of aggregates, such asvolume change (expansion, shrinkage or crystalline inversion) anddecomposition, can affect these maximum temperatures, along withthe chemical composition of both aggregate and binder and thereactivity between these mix constituents.

Temperature stability of the aggregate determines the maximumservice conditions below approximately 2400 F (1320 C).Therefore, any type of calcium aluminate cement can be used atthese temperatures. For conditions above 2400 F (1320 C), binderpurity also becomes a design factor. Generally, the low puritybinder can be used with proper aggregates up to 2700 F (1480 C),intermediate purity to 3000 F (1650 C) and high purity to 3400 F(1870 C).

Aggregate gradation is an important consideration in designingrefractory concrete. Table 3.3b provides suggested guidelines fornominal maximum size and grading of refractory aggregates.

TABLE 3.3b - Aggregate grading444444444444444444444444444444444444444444444444444444444444444444444444444444444 Maximum size, aggregate (except for gun placement) 1-1/2 in. (3.81 cm)

Maximum size, aggregate for normal gun placement 1/4 in.* (0.64 cm)

Maximum size, insulating crushed firebrick 1 in. (2.54 cm)

Maximum size, expanded shales and clays 1/2 in. (1.27 cm)

Maximum size, with the above exceptions, should not be greater then 20-25 percent of the concrete minimum dimension.

Aggregate of 1/2 in. (1.27 cm) or larger size: Retained on No. 8 Sieve = 50 percent Passing No. 100 Sieve = 10-15 percent

Aggregate of less than 1/2 in. (1.27 cm) maximum size: Retained on No. 50 Sieve = 75 percent Passing No. 100 Sieve = 10-15 percent444444444444444444444444444444444444444444444444444444444444444444444444444444444*In special cases larger sizes have been used successfully. For refractory mix designs a 1:3 or 1:4 by bulk volume drybasis cement: aggregate mix is generally used to satisfy typicalapplications. In certain cases the ratio may change from as lowas 1:2 to as high as 1:6, with the latter being used forlightweight concretes. Within the range of normal usage,increasing the cement content will provide higher strengthdevelopment. However, increased cement content may also result inincreased shrinkage. A higher aggregate content will increaseinsulating or refractory properties, depending on the type ofaggregate selected for the mix. Combinations of variousaggregates can be made to secure the desirable properties ofeach.

3.3.1 Lightweight aggregates--Perlite, expanded shale, expandedfireclay, and bubble alumina are the more commonly usedlightweight aggregate for commercial insulating concretes.

3.4 Effects of extraneous materials

Extraneous materials commonly associated with portland cements,either as admixtures or as contaminants from equipment orsurrounding conditions, may behave differently when used withcalcium aluminate cement mixes. Many castables containproprietary additions which may be adversely affected by fieldadmixtures.

Chapter 4--Composition and proportioning

4.1 Introduction

In designing mixes, refractory concretes are not only definedby density but also by operating temperature. Refractoryconcretes fall into three subclasses based on service temperatureranges. The first subclass is "ceramically-bonded concrete,"defined as concrete in which the cement binder and the fineaggregate particles react thermochemically to form a bond. Thisbond is referred to as the ceramic bond and may occur attemperatures as low as 1650 F (900 C). The second subclass is"heat resistant concrete," defined as concrete in which thecement has dehydrated but has not formed a ceramic bond. Thethird category is concrete which still has some hydraulic bondwhen heated but performs satisfactorily under cyclic conditions.

4.3 Field mixes

4.3.1 Ceramically bonded concrete--The ceramic bond can beformed at temperatures as low as 1650 F (900 C). To aid formationof the ceramic bond, concretes operating above this temperatureshould have 10-15 percent of the aggregate passing a No. 100sieve. Most field insulating concretes are made with pre-soakedaggregate. Since the specified proportions are based on drymaterials, the actual batch mixes may require correction.

4.3.2 Heat resistant concrete--This concrete is generally usedin the range 930 F (500 C) to 1650 F (900 C). Many coarseaggregates are unsuitable for use as refractory aggregatesbecause they contain quartz, which has a large volume change atl065 F (575 C).

4.4 Water content

A majority of the aggregates used in refractory and heatresistant concretes have high water absorbency. For this reasonspecific water/cement ratios are generally not used in developingmix designs. Instead, water requirements are arrived at byperiodically conducting a "ball-in-hand" test (ASTM C860). Thistest is illustrated in Fig. 4.4.

The correct water content is that which will provide a placeable,rather than a pourable, mix. When using well-soaked aggregates,it may be necessary to add little or no water at the mixer. It issometimes found that a mixture which appears fairly stiff when

discharged from the mixer will yield excess water as the concreteis placed.

Chapter 5--Installation

5.1 Introduction

Regardless of the quality of the refractory cement, aggregate,and/or castable, and regardless of the research devoted to theselection of correct materials for a specific application,maximum service life will not be obtained unless the refractoryconcrete is installed properly.

The most frequently used methods of installing refractoryconcretes are casting and shotcreting.

5.2 Casting

5.2.1 Mixing--Proper mixing of castables is of primaryimportance. Care should be taken to avoid mixing previouslyhydrated material into fresh refractory concrete. Mixers, toolsand transporting equipment used previously with portland or othertype cement concretes must be cleaned prior to mixing. Remains oflime, plaster, or portland cement will induce flash set and willlower refractories. Generally, paddle mixers are used for small to medium size jobsinvolving calcium aluminate cement concretes. In a paddle mixer,normal weight refractory concretes should be mixed for about 2 to4 min. Refractory concretes of less than 60 lbs/cu ft (960kg/m.3-) density should be mixed no longer than necessary toinsure thorough wetting. This precaution is necessary because thelightweight aggregate may break-up during the mixing action andreduce the effectiveness of the concrete as a heat insulator.Refractory concretes in the 75 to 90 lb/cu ft (1200-1400 kg/m.3-)range should be mixed for approximately 2 to 5 min. Becauseworking time may be short, all castables should be castimmediately after mixing.

5.2.3 Mixing and curing temperature--Mixing and curingtemperature can affect the type of hydrates formed in setconcrete. A castable develops its hydraulic bond because ofchemical reactions between the calcium aluminate cement andwater. To get the maximum benefits from these chemical reactions,it is preferable to form the stable C+3,AH+6, during the initialcuring period. The relative amount of C+3,AH+6, formed versusmetastable CAH+10, and C+2,AH+8, can be directly related to thetemperature at which the chemical reactions take place.

Recent work illustrates the significant impact of mixing andcuring temperatures on strength properties. Fig. 5.2.3[34] showsthe flexural strength of a tabular alumina, high purity cementcastable plotted as a function of mixing and curing temperatures.

It can be seen that the strength developed after mixing andcuring at 85 F (30 C) and drying at 230 F (110 C) is nearly twicethat of the concrete mixed and cured at 60 F (15 C) and dried at230 F. Explosive spalling of high purity cement concretes can occurwhen casting and curing temperatures below 70 F (21 C) are used.Thus, a refractory concrete containing a high purity cementshould be cast or cured above 70 F (21 C). This spallingphenomenon is less likely to occur with low or intermediatepurity cement binders.

5.2.4 Transporting--Other than shotcreting and pumping, thetechniques for transporting refractory concretes are similar tothose used for portland cement concrete. Some calcium aluminatecement binders have a shorter placing time available.

5.3 Shotcreting

Shotcreting of refractory concrete is particularly effectivewhere, (1) forms are impractical, (2) access is difficult, (3)thin layers and/or variable thicknesses are required, or (4)normal casting techniques cannot be employed. 5.3.1 Equipment--There are two basic types of shotcretemethods; dry-mix and wet-mix. The dry-mix method conveys theaggregate and binder pneumatically to the nozzle in anessentially dry state where water is added in a spray. The wet-mix method conveys the aggregate, binder and a pre-determinedamount of water, either pneumatically or under pressure, to thenozzle where compressed air is used to increases the velocity ofimpact. The dry method, though it produces greater rebound, isthe most suitable and recommended technique for shotcretingrefractory concrete. An exception is the recommended use of awet-mix gun for hot patching.

5.3.2 Installation--To ensure a uniform covering free oflaminations and with minimum rebound, the nozzleman should movethe nozzle in a small circular orbit and where possible, maintainthe flow from a 3-4 ft (0.9-1.2 m) distance at right angles tothe receiving surface.[35] The shotcrete should be left in itsas-placed state. If for some reason scraping or finishing isrequired, the absolute minimum should be done so as to avoidbreaking the bond or creating surface cracks. Shotcreting of

refractory concretes can increase the in-place density and resultin other changes in the physical properties. This effect is morepronounced in lower density castables, and must be taken intoaccount when specifying thicknesses and material quantities forinsulating applications. The user should be aware that certainaspects of portland cement concrete shotcrete practice do notapply to refractory shotcrete.

5.4 Pumping and extruding

Certain refractory concretes can be installed with positivedisplacement pumps in conjunction with rigid or flexiblepipelines. The design of the mix is critical, and specialattention must be given to the absorptive characteristics andsizing of the aggregate.

Some applicators use the term "extruding" to describe theconveying and placing of refractory concrete at velocities thatare very low or close to zero on exit from the pipeline. Whenextruding, mixing of the refractory castable and water can bedone internally or externally depending on type of extrudingdevice.

5.5 Pneumatic gun casting

Pneumatic gun casting, or gun casting, is a relatively newtechnique for casting concrete and is finding increased uses forrefractory concrete. Conventional dry shotcrete equipment andprocedures are utilized with the exception that an energyreducing device is attached to the nozzle body in place of thestandard shotcrete nozzle tip. 5.8 Finishing

Surface finishing or rubbing of refractory concretes should bekept at a minimum. Use of a steel trowel should be avoided, andthe final surface can be lightly screeded to grade but should notbe worked in any manner.

Chapter 6--Curing, drying, firing[8,16,17,18]

6.1 Introduction

Refractory concrete should be properly cured for at least thefirst 24 hr. Following this curing it should be dried at 220 F(105 C), and then heated slowly until the combined water has beenremoved before heating at a more rapid rate.

6.2 Bond mechanisms

Calcium aluminate cements have anhydrous mineral phases whichreact with water to form alumina gel and crystalline compoundswhich function as a binder for the concrete.[20,21] The hydrationof these cements (Fig. 6.2) is exothermic.

The rate of the chemical reaction is relatively fast.[22] For allpractical purposes, calcium aluminate concretes will develop fullstrength within 24 hr of mixing.

The total drying shrinkage of calcium aluminate cementconcretes in air, is comparable to that of portland cementconcrete. In order to provide for complete hydration, and tocontrol drying shrinkage, special attention must be given to thecuring of refractory concretes.

6.3 Curing

The temperature of hardening calcium cement rises rapidly. Ifthe exposed surfaces are not kept damp, the cement on the surfacemay dry out before it can be properly hydrated. The applicationof curing water prevents the surface from becoming dry andfurnishes water for hydration. In addition, the evaporation has acooling effect which helps to dissipate the heat of hydration.

Conversion of the high alumina cement hydrates, which occurs ifthe cement is allowed to develop excessive heat, does not presentthe same problem in refractory concretes that it does in highalumina cement concretes used for structural purposes. It hasbeen shown that if refractory concrete is fully converted byallowing it to harden in hot water and then heated to 2500 F(1370 C), the fired strength is equal to that obtained for wellcured concrete. When possible, however, refractory concreteshould be kept cool by appropriate curing under 210 F (99 C) fortwo reasons:

1The entire refractory concrete structure does not usually reachthe maximum service temperature, and the higher cold strengthsobtained by good curing may be useful in the cooler portions ofthe refractory.

1If the temperature within the concrete reaches a high levelduring hardening, the thermal stresses produced during coolingmay be sufficient to cause cracking.

Curing should start as soon as the surface is firm. Under

normal atmospheric temperatures, this will occur within 4 to 10hr after mixing the concrete. The concrete should be kept moistfor 24 hr by covering with wet burlap, by fine spraying or byusing a curing membrane. Alternate wetting and drying can bedetrimental to the cure of the concrete.

When using a curing membrane, the compound should contain aresin and not a wax base, and should be applied to the surface assoon as possible after placing and screeding. The reason fordiscouraging the use of wax is that a hot surface will melt thewax, causing it to be absorbed into the concrete, breaking themembrane.

6.4 Drying

The large amount of free water in the refractory concretenecessitates a drying period before exposure to operatingtemperatures. Otherwise, the formation of steam may lead toexplosive spalling during firing.

6.5 Firing

Following drying of the refractory concrete, the first heat-upshould be at a reasonably slow rate. A typical firing schedule,for a 9 in. (22.9 cm) thick lining, consists of applying a slowheat by gradually bringing the temperature up to 220 F (105 C),and holding for at least 6 hr. The temperature is then raised ata rate of 50-100 F (10-40 C) per hr up to 1000 F (540 C) andagain held for at least 6 hr. The first hold is to allowremaining free water to evaporate, and the second hold is toeliminate the combined water without danger of spalling. Beyond 1000 F (540 C), the temperature of the refractoryconcrete can be raised more rapidly. Calcining of the greenconcrete into a refractory structure will take place between 1600F (820 C) and 2500 F (1370 C). Wall thickness and mix variationsmay require somewhat different rates of heating, but the holdtemperatures should remain at least 6 hr.

If steam is observed during heat-up, the temperature should beheld until steam is no longer visible.

Chapter 7--Properties of Normal Weight Refractory Concretes

7.1 Introduction

There are various physical properties and tests which arestandard in the refractory industry and these are usuallyprovided in the material specifications. Table 2.1a is an exampleof typical data for normal weight refractory concrete.

7.2 Maximum service temperature

The recommended maximum service temperature will normallyassume that the castable will be used in a clean, oxidizingatmosphere, such as is present when firing with natural gas. Themaximum service temperature is usually determined as the pointabove which excessive shrinkage will take place. It is about150-200 F (70-90 C) below the actual softening point of the

concrete.

If a fuel has solid impurities, such as in coals or heavy fueloils, or if the solids or dust in the process contact therefractory, the maximum permissible service temperature willusually be considerably reduced. Solid impurities can react withthe concrete and produce compounds of lower melting point whichmelt and run. This is generally referred to as slagging. Thelower softening point thus represents a limit for the operatingtemperature. Slag forming reactions usually do not occur belowabout 2500 F (1320 C) except in the presence of alkalies wherereactions can occur in the 1900-2000 F (1040-1090 C) range.

A reducing atmosphere can lower the melting point and hence themaximum operating temperature by 100-200 F (40-90 C) ifsufficient quantities of iron compounds are present in therefractory.[3]

7.4 Shrinkage and expansion

In discussing shrinkage and expansion of a refractory concrete,it is important to define the distinction between the independenteffects of permanent shrinkage or expansion and reversiblethermal expansion. Permanent change is determined by measuring aspecimen at room temperature, heating it to a specifiedtemperature, cooling to room temperature, and remeasuring it. Thedifference between the two measurements is the permanent change,which occurs during the first heating cycle. Subsequent heatingto the same or lower temperature will have little or noadditional effect on the permanent change. Heating to a highertemperature may cause some additional permanent change.

Reversible thermal expansion of a specimen which has beenpreviously stabilized against further permanent change, is thedimensional change as a specimen is heated. Upon cooling, thespecimen contracts to its original size.

At any given temperature, the net dimensional change of arefractory concrete is the sum of the reversible expansion andthe permanent shrinkage corresponding to the highest temperatureto which the castable has been heated.

7.4.1 Permanent shrinkage and expansion--The initial heating ofa refractory concrete usually causes shrinkage. At highertemperatures permanent expansion can occur. This effect, whichvaries with the maximum temperature attained, must be consideredwith reversible thermal expansion when calculating the netexpansion (or shrinkage) at service temperature. The ASTM ratingof castables is based on no more than 1.5 percent permanentlinear shrinkage occurring at prescribed temperatures (ASTM C64and C401). Most normal weight refractory concretes will have lessthan 0.5 percent permanent linear shrinkage after firing at 2000F (1090 C).

The permanent change appears as cracks after the first firing.These cracks will generally be about 2-3 ft (0.6-0.9 m) oncenters, and may vary, depending on the concrete thickness andthe anchor spacing. Usually, the width of the cracks at roomtemperature is partly dependent on the permanent shrinkage.Normally, the cracks will be tightly closed at operatingtemperatures. Such cracking, which may start during drying, is to

be expected and will not adversely affect the service performanceof the refractory.

7.4.2 Reversible thermal expansion--The reversible thermalexpansion of most refractory concretes is approximately 3 x 10 -6in./in./F (5 x 10 -6 cm/cm/C). However, the expansion coefficientmay be as high as 4 x 10 -6 in./in./F (7 x 10 -6 cm/cm/C) forhigh alumina concretes and to 5 x 10 -6 in./in./F (9 x 10 -6cm/cm/C) for chrome castables. Fig. 7.4.2 shows typical lengthchanges due to permanent shrinkage and reversible expansion.

7.5 Strength

7.5.1 Modulus of rupture--Modulus of rupture is measured bymeans of a flexure test and is considered as a measure of tensilestrength (ASTM C268). The extreme fiber tensile strengthcalculated from this test will be 50 to 100 percent higher thanthe tensile strength derived from a straight pull test. Typicalmodulus of rupture values are 300 to 1500 psi (2.07-10.4 MPa).Shotcreting can increase modulus of rupture values by up to 50percent.

Fig. 7.5 shows typical trends of modulus of rupture strengthversus temperature.

7.5.2 Cold compressive strength (crushing)--The test isordinarily run on 9 x 4-1/2 x 2-1/2 in. (22.9 x 11.4 x 6.4 cm)specimens 9 in. (22.9 cm) straights in brick terminology withpressure applied to the smallest surface (ASTM C133). Failure inthis test is generally due to shear.

Crushing strengths vary from 1000 to 8000 psi (6.9 to 55.2MPa). Typically, compressive strengths are three to four timesgreater than modulus of rupture values.

7.6 Thermal conductivity

For normal weight refractory concretes, thermal conductivitytends to vary with density. Typical values (k factors) range fromabout 5 Btu-in./sq ft -hr-F (72 W -cm/m²-C) for 120 pcf (1920kg/m.3-) material to about 10 Btu-in. /sq ft -hr -F (144W-cm/m²-C) for 160 pcf (2560 kg/m.3-) material. There is usuallyan increase in thermal conductivity with temperature.

7.10 Specific heat

The specific heat of a refractory concrete increases withtemperature from about 0.20 Btu/lb/F (837 J/ kg-C) at 100 F (40C) to about 0.29 Btu/lb/F (1210 J/ kg-C) at 2500 F (1370 C). Thiscan vary plus or minus 0.025 units, depending on the aggregate.

Chapter 8--Properties of lightweight refractory concretes

8.1 Introduction Refractory concretes are widely used as insulating materials.They have a wide range of densities [20 to 100 pcf (320 to 1600kg/m.3-)] and can be formulated to have high maximum servicetemperatures and relatively high strengths. This often allows theuse of these materials as single component, exposed servicelinings.

Table 2.1b shows physical property values for typicallightweight refractory concretes.

8.4 Shrinkage and expansion

The reversible thermal expansion of lightweight concretes willvary from 2.5 x 10 -6 to 3.5 x 10 -6 in./in./F (4.5 x 10 -6cm/cm/C). Because of compensating permanent shrinkage, thethermal expansion of lightweight refractory concrete is normallyinsignificant and is usually ignored in the design of lightweightrefractory concrete systems.

8.5 Strength

Strengths of lightweight refractory concrete are measured byboth a modulus of rupture and a crushing test.

8.5.1 Modulus of rupture--Typical values range fromapproximately 50 (0.3 MPa) to 400 psi (2.8 MPa).

Table 8.5.1 shows the difference between the cold and hot

modulus of rupture for a typical 2800 F (1540 C) lightweightrefractory concrete.

TABLE 8.5.1. Hot and cold modulus of rupture of a 2800F (1538C)lightweight refractory concrete containing expanded fireclayaggregate44444444444444444444444444444444444444444444444444444444444444444 Modulus of rupture, psi (MPa)

(Hot tested (Cold tested after at temperature) firing and cooling)))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))))) 230F (110C) 350 (2.4) 350 (2.4)1000F (538C) 300 (2.1) N.D.*1500F (816C) 250 (1.7) 250 (1.7)2000F (1093C) 210 (1.4) 225 (1.6)2500F (1371C) 240 (1.7) 470 (3.2)2700F (1482C) 90 (0.6) 800 (5.5.)44444444444444444444444444444444444444444444444444444444444444444*N.D. = Not Determined 8.5.2 Cold compressive strength (crushing)--Cold crushingstrengths vary from 200-500 psi (1.4-3.5 MPa) for lightweightrefractory concretes with densities up to 50 pcf (800 kg/m.3-).For materials having densities in the 75-100 pcf (1200-1600kg/m.3-) range, the cold crushing strength varies from 1000-2500psi (6.9-17.3 MPa).

8.6 Thermal conductivity

Thermal conductivity is one of the most important physicalproperties of a lightweight refractory concrete and is controlledprimarily by the density of the concrete. For hydraulicallybonded, alumina-silica concretes, a usable correlation existsbetween concrete density [after drying at 230 F (110 C)] and thethermal conductivity (k factor). Typically, the thermalconductivity for insulating concretes ranges from 1 to 4Btu-in./sq ft-hr-F (0.1 to 0.6 W/M²-C).

8.10 Specific heat

The specific heat of a lightweight refractory concrete isapproximately the same as that of normal weight concrete. Therange is from 0.2 Btu/lb/F (837 J/kg-C) at 100 F (40 C) toapproximately 0.3 Btu/1b/F (1255 J/kg-C) at 2500 F (1370 C).

Chapter 9--Construction details

9.1 Introduction

Construction details are an important ingredient in thesuccessful application of refractory concrete. Proper designdetails and careful implementation are essential, and parameterssuch as support structure integrity, forms, anchors, andconstruction joints have a major influence on the overall qualityand performance of refractory concrete installations.

9.2 Support structure

Normally, refractory concrete is permanently supported by aback-up structure. The support material is usually bolted orwelded steel which, prior to installation of the refractoryconcrete, should be checked to ensure that there is no warpageand that all joints are structurally sound and tight.

9.3 Forms

Both metal and wood forms are used for refractory concrete. 9.4 Anchors[41,44,45,46]

An anchor is a device used to hold refractory concrete in astable position while counteracting the effects of dead loads,thermal stressing and cycling, and mechanical vibration. Anchorsand anchoring systems are not designed to function asreinforcement.

Anchors are produced as alloy steel rods or castings, andprefired refractory ceramic shapes. The requirements of aparticular installation will determine the type and positioningof anchors. Typical factors to be considered are: unit size, wallthickness, number of refractory concrete components, area ofapplication, and service temperature.

9.4.1 Metal anchors--The most frequently used metal anchors areV-clips, studs, and castings. However, in special applications,welded wire fabric, hex steel and chain link fencing are used.Generally, metal anchors are extended from the cold face for 2/3to 3/4 of the lining thickness and are staggered to avoidformation of planes of weakness.

Metal V-clips, stud anchors and castings are available incarbon steel, Type 304 stainless alloy, Type 310 stainless alloy,and other suitable alloys. The choice of material depends on thetemperature to which the anchors will be exposed. Carbon steelcan be used for anchor temperatures of up to 1000 F (540 C). Type304 stainless is suitable for anchor temperatures of up to 1800 F(980 C) and Type 310 stainless is adequate up to 2000 F (1095 C).Depending on the grade of alloy, alloy steel castings can sustaina maximum temperature of between 1500 F (815 C) and 2000 F (1095C).

9.4.2 Pre-fired refractory anchors (ceramic anchors)--Theprincipal use of ceramic anchors is to anchor refractory plastic,rather than refractory concrete. However, ceramic anchors areused in areas where refractory concrete is subjected to highservice temperature. In addition, they are sometimes used as asubstitute for metal anchors where concrete thicknesses are 9 in.(230 mm), or greater.

Ceramic anchors usually are composed of refractory aggregates,clays, and binders. They are mechanically pressed into shapeswhich provide for attachment to either the wall or roof and areribbed to aid in securing the refractory concrete. Ceramicanchors are pre-fired at elevated temperature to provide astrong, dense structure. Depending on the composition, serviceconditions, and other factors, ceramic anchors are available withmaximum service temperature ratings of up to 3200 F (1760 C).

Ceramic anchors are attached to structural wall or roofsupports by bolts and/or metal support castings. In order tominimize the tendency of the refractory concrete to sheet spall,the hot face of the ceramic anchor should extend to the hot faceof the refractory concrete. 9.4.5.1 Thin single component linings. Plain metal chain linkfencing is often used to anchor single component linings, lessthan 2 in. (50 mm) thick, composed of lightweight or mediumweight refractory concrete and exposed to low to moderatemechanical stresses and/or service temperatures.

9.4.5.2 Single component linings up to 9 in. (230 mm) thick.Normally, single component linings 2 in. (50 mm) to 9 in. (230mm) thick, composed entirely of lightweight, medium weight ornormal weight refractory concrete, and exposed to moderatestresses and service temperatures use metal anchors.

9.4.5.3 Single component linings greater than 9 in. (230 mm)thick. Normal weight refractory concrete linings, greater than 9in. (230 mm) thick, utilize either ceramic or metal anchors. Thetype of anchor chosen will depend on the operating parameters. 9.4.5.4 Roofs. Two types of anchor systems, internal andexternal, are used for single component roofs. The choice dependson roof thickness and on construction and design preferences.

9.4.5.5 Multicomponent linings. Multicomponent linings of 9in. (230 mm) or less in thickness which are subjected to moderateservice temperatures and mechanical stresses should employ metalanchors.

Multicomponent linings of 9 in. (230 mm) or greater thickness,composed of a combination of lightweight or medium weightrefractory concrete as back-up in conjunction with a normalweight refractory concrete, can use a combination of ceramic andmetal anchors.

With multicomponent shotcrete linings, the back-up component isapplied directly to the shell and provisions must be made eitherto protect the anchor (metal or ceramic) from rebound build-up,or to clean the anchor after placing of the back-up layer.Rebound build-up can destroy the grip between the heavy weightrefractory concrete and the ceramic anchor.

9.5 Reinforcement and metal embedment

The use of steel as a reinforcement should be avoided. Ingeneral, the metal will cause cracking due to the differentialexpansion, caused by temperature or oxidation, between the metaland concrete. For the same reason heavy metal objects such asbolts, pipes, etc. should never be embedded in refractoryconcrete.

9.6 Joints[37,48]

In cast installations, construction joints occur at thejunction of walls and roofs or where large placements are brokeninto separate sections. Cold joints of this type will not bondand should be avoided where it is necessary to contain liquid orgases.

It is often necessary to include a provision for expansion.Expansion joints can be formed by inserting materials such aswood, cardboard, expanded polystyrene or ceramic fiber in theappropriate location.

Shotcrete installations require construction joints attransitions between materials, or when application must becurtailed due to shift changes or material supply. In thesecases, the in situ refractory concrete should be trimmed back toproduce a clean edge perpendicular to the shell. Expansioncompensating materials are not generally inserted into this typeof joint. If a joint edge is allowed to stand for a prolongedperiod of time (more than 4 hr), it should be thoroughlymoistened before any new material is applied.

Chapter 10--Repair

10.1 Introduction

Repair of refractory concrete should be considered only wheneconomics dictate that cost and downtime do not justify completereplacement. Before undertaking a repair, an effort should bemade to determine the cause of the previous failure. If possible,the design and/or construction details should be modified toreduce the possibility of a recurrence of failure and to prolongservice life between repairs.

Hot repair techniques are valuable for minimizing downtime andfor extending an operating run until a scheduled shutdown. Hotrepairs are especially suitable for temporary repairs oflocalized failures and hot spots.

10.2 Failure mechanisms

Some of the phenomena that can cause failure are:

(1) Thermal stress and thermal shock;

(2) Exposure to excessive temperatures;

(3) Mechanical loading;

(4) Erosion and abrasion;

(5) Corrosive environments;

(6) Anchorage failures and

(7) Operational problems or upsets. 10.3 Surface preparation

When the installation to be repaired is made of mortar orconcrete, it is important to prepare the surface of the oldmaterial so that a mechanical bond will be formed between it andthe new refractory concrete. No significant chemical bond will beformed, and adhesion of the repair material must depend primarilyon the mechanical bond. Preparation of the surface requiresremoval of all deteriorated or spalled materials and roughening

of the exposed sound surface of the old concrete. In all cases,the chipping of old material must leave a flat base, and squareshoulders approximately perpendicular to the hot face, completelyaround the perimeter of the repair section. If this is doneproperly, there is no need to chamfer the edges or providefillets to walls and floors. Once initial removal of looseconcrete has been completed, the old refractory should be soundedwith bars or hammers to make certain only sound material remains.

Areas that were not chipped should be thoroughly sandblasted toremove any traces of soot, grease, oil or other substances thatcould interfere with the bond. Excess sand and loose debris mustthen be blown from the surface with compressed air. Particularcare must be taken to remove any debris from around the anchors.

10.4 Anchoring and bonding

If possible, patches should be anchored with a minimum of twoanchors which should be solidly attached to the shell. In caseswhere this is impossible, anchors should be solidly embedded inthe old refractory. Ceramic anchors should extend to the hot faceof the new refractory concrete. Otherwise, sheet spalling mayoccur. If metal anchors are used, they should be brought as closeas possible to the hot face. The distance will depend on themetallurgy of the anchors and the thermal conductivity of theconcrete.

Where anchors are not practical, or repairs are shallow,mechanical bonding will be aided by cutting chases or keyways ina waffle pattern across the entire surface of the repair sectionand by slightly undercutting the existing refractory.

In certain limited applications, where other means are notavailable, the bond may be improved by pre-coating the surface tobe repaired with a bonding agent. When repairing refractoryconcrete with a similar cast-in-place material pre-wetting isrequired, and use of a neat calcium aluminate cement slurry mayimprove bonding.

10.5 Repair materials

A wide range of repair products is available for repairingrefractory concrete. However, it is usually best to use amaterial similar to that being repaired. Refractory concrete is frequently used as a repair material andperforms satisfactorily in many situations. Among the otheravailable repair materials are the following:

1. Air setting mortars;

2. Phosphate-bonded and clay-based heat-setting mortars;

3. Steel-fiber reinforced refractory concrete; (Steel-fiberreinforced refractory concrete will generally exhibit superiorresistance to cracking and abrasion. However, the fibers will notperform well if the temperatures to which they are exposed induceoxidation. If the conditions are such that the fiber-reinforcedsystem is above the oxidizing, but below the melting temperatureof the particular fibers being used, it is possible that they maystill be utilized, depending on the temperature gradient through

the concrete, the furnace atmosphere, the permeability of theconcrete, the severity and frequency of temperature cycles, theexposure time at maximum temperature, and the mechanicalloading.)

4. Plastic refractories and ramming mixes; and

5. Hot repair materials. Some of the repair materials used forhot patching contain calcium aluminate cement as the principalbinder, however, most do not. The latter utilize non-hydraulicand chemical binders (see Section 1.6.4). Since these materialsare intended for temporary repairs, they may not have servicelife or properties equivalent to those in the original lining.

While field mixes can be used for hot gunning, mostapplications use proprietary (prepackaged) materials which arespecially designed for specific conditions of installation. Somemanufacturers have designed special spray or gunning equipmentand maintenance programs to install their hot repair materials ona planned basis.

10.6 Repair techniques

10.6.2 Refractory concrete--When a refractory concrete isselected to effect repairs, the type of placement procedure mustinsure that the full thickness of the repair section is installedin as short a time as possible, preferably in a single lift.

When refractory concrete is placed by the shotcrete method,certain precautions must be followed.[35] The area being repairedmust be delineated in advance so that the concrete can be shot tothe full section depth or thickness before any layer develops aninitial set.

It is important that the refractory concrete be cured properlyduring the 24-hr period following placement (see Section 6.3).After the concrete has been moist-cured for 24 hr, drying andfiring can be initiated (see Sections 6.4 and 6.5). Speeding upthe moist-curing, drying and firing can result in a markedreduction in the physical properties and life of the repair. 10.6.3 Plastic and ramming mixes--A refractory mortar coatingmay be used to improve bonding when repairing refractory concretewith a plastic or ramming mix. In order to achieve high densityand prevent laminations, it is recommended that plasticrefractories be installed by the pneumatic ramming method using asteel wedge-type head. The basic pattern of ramming should be tobuild up layers of plastic on top of the backing wall. Theplastic is placed in strips and laid at right angles to theforms. It is important to angle the pneumatic rammer so that thestrips are driven against the form, and side-ways against thepreviously installed material. The repaired area should betrimmed to a rough surface for more uniform drying.

Moisture escape holes should be made by inserting a 1/8 in. (3mm) diameter pointed rod, approximately two-thirds of the depthof the material, on approximately 6 in. (150 mm) centers. Inorder to prevent formation of an outer skin, which can seal inmoisture, a short period of forced drying of air-setting plasticrefractories is desirable. Excessive temperature or direct flameimpingement, which will seal the surface and prevent escape of

moisture, must be avoided.

The following heat-curing procedure has been found to give goodresults with plastic and ramming mixes: Remove all free moistureat a temperature of not over 250 F (120 C). Following removal offree and absorbed moisture, raise the temperature at a rate of75-100 F (42-56 C)/hr until the desired operating temperature isreached. If steam is observed during heat-up, hold the presenttemperature until it stops.

Whenever possible, repairs using plastic mixes should becarried out immediately prior to heat-up. A properly burned-inplastic will exhibit less cracking than a plastic exposed tolengthy air drying.

10.6.4 Steel-fiber reinforced refractory concrete

10.6.4.1 Cast-in-place mixes. A problem with steel fibers istheir tendency to "ball-up." Clusters of fibers can be broken upby hand feeding or shaking of the sieve before addition to theconcrete mix. In some cases, vibration will tighten up the fiberclusters and it is not a recommended method of fiber dispersal.

The addition of steel fibers tends to reduce the workability ofthe mix. Normally, this can be overcome by internal or externalvibration. Use of additional water is not recommended since thiswill degrade cured strength and increase the porosity.

10.6.4.2 Shotcrete mixes. Steel fiber reinforced refractoryconcretes can be shot into place by either the wet or dryprocess. Fiber lengths approaching the internal diameter of thematerial hose or nozzle can be shot successfully. Because reboundof the fibers can be dangerous, the nozzleman and support crewshould wear protective clothing when dry shooting with steelfibers. 10.6.5 Hot repair procedures--Hot repair procedures are basedon standard shotcreting technology. However, because of the hightemperatures, certain differences are necessary. Compared tonormal shotcreting, the high temperatures require a speciallydesigned nozzle and an excessive amount of water in the mix inorder to insure proper delivery, impingement, compaction, andmaterial retention.

Hot shotcreting requires that the nozzleman and a helper standoutside the furnace and manually or mechanically manipulate anextended nozzle or "lance" within the furnace. Special ports oropenings must be provided in the furnace for proper access. Thelength, size, and design of the nozzle depends on the furnaceconfiguration, temperature, and type of application.

In general, the best bonds are achieved when the vesselinterior is a red or orange color [1500-1700 F (815-925 C)]. Therefractory concrete repair must be allowed to heat-cure prior toplacing the unit back in service. The length of time toaccomplish this, although usually brief, will depend on thetemperature at the time of repair, the type of material used forthe repair, and the thickness of the installed material.

Chapter 11--Applications

11.1 Introduction

Refractory concretes are currently used in a wide variety ofindustrial applications where pyroprocessing or thermalcontainment is required. Because there are literally hundreds ofrefractory concretes available, it is impossible to discuss everycomposition and its application. Accordingly, only the moreimportant applications, where refractory concretes have been usedsuccessfully, are reviewed. Included in the review are thefollowing industries:

(a) Iron and steel

(b) Non-ferrous metal

(c) Petrochemical

(d) Ceramic processing

(e) Glass

(f) Steam power generation

(g) Aerospace

(h) Nuclear

(i) Gas production

(j) MHD power generation (k) Lightweight aggregate

(1) Incinerator

(m) Cement and lime

Chapter 12--New development and future use of refractory concrete

12.1 Introduction

Traditionally, developments in the refractories industry havebeen closely related to the process industries, the primarycustomers for the product.

In recent years, there have been marked changes in theproduction and use of refractories. A number of factors havecontributed to these changes including:

(a) development of new and improved industrial processes,

(b) demand for higher temperatures and increased productionrates associated with the above developments,

(c) improvement in the quality of refractory products andincreased use of different types of refractories, especially themonolithic castables and,

(d) increased technical knowledge of the service behavior ofrefractory materials.

With these technological advancements, investigations into theuse of refractory concretes for special applications isincreasing. Typical of these new and proposed applications areincinerators, coal gasification plants, chemical process plants,steel plants, and foundries.

12.2 New developments

12.2.1 Steel fibers[187,188,189,191]--The following potentialadvantages are offered by the use of steel-fiber reinforcement inmonolithic construction:

(a) improved flexural strength at ambient and elevatedtemperatures,

(b) improved thermal and mechanical stress resistance, (c) improved thermal shock resistance,

(d) improved spall resistance, and

(e) improved load-carrying ability.

However, degradation of the steel fibers at high temperaturecan occur under service conditions and, therefore, limit the fullpotential of these materials. Note: See References 197 through205.

12.2.2 Shotcrete--The use of shotcrete for new refractoryconstruction and for repairs is a rapidly growing field andsuccessful results have been achieved in many applications.

12.2.3 Precast shapes--Increasingly, precast shapes are beingused for special conditions and this trend will continue.

12.3 Research requirements

Unfortunately, selection and use of refractory concretes isstill considered an art and, with a few exceptions, theproperties of refractory concretes are not utilized in rationaldesign schemes. In many instances, the wrong properties are beingmeasured or the available data are not being used correctly.

Future research efforts should be directed towards obtaining abetter understanding of the behavior of refractory concretesunder service conditions. Increased emphasis will be placed onelevated temperature properties and how they are influenced bysuch factors as proportioning, grading and composition.

Areas of needed research include the following:

(a) Dimensional stability

(b) Chemical attack

(c) Mechanical properties

(d) Property measurements and tests

(e) Process conditions

(f) Rational design procedures

References

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3. Norton, F. H., Refractories, 4th Edition, McGraw-Hill BookCompany, New York, 1968, 782 pp.

5. Robson, T. D., High Alumina Cements and Concretes, JohnWiley and Sons, New York, 1962, 263 pp.

20. Chatterji, S., and Jeffry, J. W., "Microstructure of SetHigh-Alumina Cement Pastes," Transactions, British CeramicSociety (London), V. 67, May 1968, pp. 171-183.

21. Midgley, H. G., "The Mineralogy of Set High-AluminaCement," Transactions, British Ceramic Society (London), 1966,pp. 161-187.

22. Wygant, J. F., "Cementitious Bonding in CeramicFabrication," Ceramic Fabrication Processes, W. D. Kingery,Editor, John Wiley and Sons, New York, 1958, pp. 171-198.

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46. Vaughn, S. H., Jr., "Guidelines for Selection of MonolithicRefractory Anchoring Systems," Iron and Steel Engineer, May 1972,p. 64.

187. Lankard, D. R., and Sheets, H. D., "Use of Steel WireFibers in Refractory Castables," American Ceramic SocietyBulletin, V. 50, No. 5, 1971, pp. 497-500.

188. Lankard, D. R.; Bundy, G. B.; and Sheets, H. D.,"Strengthening Refractory Concrete," Industrial Process Heating(London), V. 13, No. 3, Mar. 1973, pp. 34-47. 189. Lankard, D. R., "Steel Fiber Reinforced RefractoryConcrete," Refractory Concrete, SP-57, American ConcreteInstitute, Detroit, 1978, pp. 241-263.

191. Fowler, T. J., "Lessons Learned from Refractory ConcreteFailures," Refractory Concrete, SP-57, American ConcreteInstitute, Detroit, 1978, pp. 283-303.

195. Tseung, A. L. L., and Carruthers, T. G., "RefractoryConcretes Based on Pure Calcium Aluminate Cements," Transactions,British Ceramic Society (London), V. 62, 1963, pp. 305-321.

197. Peterson, J. R., and Vaughan, F. H., "Metal FiberReinforced Refractory for Petroleum Refinery Applications," PaperNo. 51, Presented at Corrosion/80, National Association ofCorrosion Engineers, Pittsburgh, 1980.

198. Crowley, M. S., "Steel Fiber in Refractory Applications,"Paper No. MC-81-5, National Petroleum Refiners AssociationRefinery and Petrochemical Maintenance Conference, Pittsburgh,1981.

199. Venable, C. R., Jr., "Refractory Requirements for AmmoniaPlants," American Ceramic Society Bulletin, V. 48, No. 12, 1969,pp 1114-1117.

200. Farris, R. E., "Refractory Concrete: Installation Problemsand Their Identification," 18th Annual Symposium onRefractories--Changes in Refractory Technology--In Place Forming,American Ceramic Society, St. Louis Section, The Engineers Club,Mar. 12, 1982.

201. MacZura, G.; Hart, L. D.; Heilich, R. P.; and Kopanda, J.E., "Refractory Cements," Ceramic Engineers and ScienceProc.--Raw Materials for Refractories Conference, (4) 1-2, 1983,pp. 46-67.

202. "Standard Recommended Practices for DeterminingConsistency of Refractory Concretes," (ASTM C 860-77), 1982Annual Book of ASTM Standards, Part 17, American Society forTesting and Materials, Philadelphia, pp. 932-957.

203. "Standard Recommended Practice for Preparing RefractoryConcrete Specimens by Casting, (ASTM C 862-77), 1982 Annual Bookof ASTM Standards, Part 17, American Society for Testing andMaterials, Philadelphia, pp. 940-946.

204. "Standard Recommended Practice for Firing RefractoryConcrete Specimens," (ASTM C 865-77), 1982 Annual Book of ASTMStandards, Part 17, American Society for Testing and Materials,Philadelphia, pp. 949-951. 205. "Standard Practice for Preparing Refractory ConcreteSpecimens by Cold Gunning," (ASTM C 903-79) 1982 Annual Book ofASTM Standards, Part 17, American Society for Testing andMaterials, Philadelphia, pp. 978-979. The complete report wassubmitted to letter ballot of the committee which consisted of 16

members; 16 members returned affirmative ballots. The precedingreport was a summary. The complete report will be available inMay as a separate publication.