2007interground limestone and cement

8/10/2019 2007Interground limestone and cement

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Interground Limestone Cement:Construction and 2-yr Performance of a Concrete Test

Section

Prepared by:

Nancy M. Whiting

Mn/DOT Office of Materials

Concrete Research Unit

This report represents the results of research conducted by the authors and does not necessarily represent the viewsor policies of the Minnesota Department of Transportation and/or the Center for Transportation Studies. This report

does not contain a standard or specified technique.

[If report mentions any products by name include this second paragraph to the disclaimer. If no products mentioned,

this can be deleted.]

The authors and the Minnesota Department of Transportation and/or Center for Transportation Studies do notendorse products or manufacturers. Trade or manufacturers names appear herein solely because they are considered

essential to this report


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Technical Report Documentation Page1. Report No. 2. 3. Recipients Accession No.

4. Title and Subtitle 5. Report Date

6.

Interground Limestone Cement: Construction and 2-yr

Performance of a Concrete Test Section

7. Author(s) 8. Performing Organization Report No.Nancy M Whiting9. Performing Organization Name and Address 10. Project/Task/Work Unit No.

11. Contract (C) or Grant (G) No.Mn/DOT Office of Materials

1400 Gervais Ave

Maplewood, MN 55109

12. Sponsoring Organization Name and Address 13. Type of Report and Period CoveredConstruction and performance report of

interground limestone cement concrete from

Oct. 2004 to Jan. 2007.14. Sponsoring Agency Code

Minnesota Department of Transportation

395 John Ireland Boulevard Mail Stop 330

St. Paul, Minnesota 55155

15. Supplementary Notes

16. Abstract (Limit: 200 words)

ABSTRACT: Several countries around the world have used interground limestone cement (ILC) for

several years in concrete construction. The results from various research projects do not all agree on theinfluence interground limestone has on the plastic and hardened properties of concrete, but most agree

that the variability can be controlled if the limestone content remains at or below 5%. To better

understand the performance of ILC, a test section of concrete flatwork was poured in a median in Baxter,Minnesota in October 2004. This test section was constructed with concrete made with and without

interground limestone in the cement. The physical and chemical properties of both cements were verysimilar. Tests of the fresh and hardened properties of both concretes placed in the field suggest very

similar properties with slightly higher strengths for the interground limestone cement. The reason for theincreased strength of the interground limestone is uncertain but may have been related to a reduced w/cm

ratio. The test section is performing well after more than 2 years. Based on this small test section itappears that mechanical properties similar to normal concrete can be achieved using


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Acknowledgements

This project is the results of tremendous work and cooperation between Holcim (US) Inc. and theMinnesota Department of Transportation (Mn/DOT). In particular the author wishes to thank the efforts

of Alfred Gardiner, Technical Service Engineer of the Northern Sales Group of Holcim (US) Inc; DougSchwartz, Concrete Engineer, Mn/DOT; Bernard Izevbekhai, Concrete Research Engineer, Mn/DOT;Kevin Kosobud, District 3 Construction Engineer, Mn/DOT; and several support engineers and

technicians at Mn/DOTs Office of Materials lab and District 3 Office. Their extra efforts and cooperation

were key in completing this project successfully.

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Table of Contents

ABSTRACT.....................................................................................................................................v

Executive Summary....................................................................................................................... vi

Chapter 1: Introduction....................................................................................................................1

Background ...............................................................................................................................1

Previous Research .....................................................................................................................1

Research Problem and Goals ....................................................................................................2

Research Approach ....................................................................................................................2

Chapter 2: Test Section Construction Report ..................................................................................3

Mix Design.................................................................................................................................3

Field Placement..........................................................................................................................3

Specimen Fabrication.................................................................................................................4

Chapter 3: Tests Results and Analyses ............................................................................................6

Physical Cement Tests ...............................................................................................................6

Chemical Cement Tests .............................................................................................................7

Hardened Concrete Tests ...........................................................................................................8

Comparing Mortar and Concrete ...............................................................................................9

Chapter 4: Two-year Performance Review....................................................................................10

Chapter 5: Summary and Conclusion ............................................................................................13

Summary..................................................................................................................................13

Conclusions and Recommendations ........................................................................................13

References......................................................................................................................................15

Appendix A:Concrete Mix Design ............................................................................................ A-1

Appendix B: Cement Properties ..................................................................................................B-1

Appendix C: ASTM C666 Freeze/Thaw Test Result ..................................................................C-1

Appendix D: Testing Summary Provided by Holcim................................................................. D-1

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List of Tables and Figures

List of Tables

Table 2.1 Mix Design ................................................................................................................3

Table 2.2 Field Test Results.......................................................................................................4

Table 3.1 Physical Cement and Mortar Properties ....................................................................6

Table 3.2 Mix Design for 2-in Mortar Cubes ............................................................................7

Table 3.3 Chemical Analyses of Cement...................................................................................7

Table 3.4 Hardened Concrete Test Results................................................................................8

Table 4.1 Daily Temperatures..................................................................................................12

List of Figures

Figure 2.1 Median Test Section.................................................................................................4

Figure 4.1 Concrete Test Section 2-Years Later......................................................................10

Figure 4.2 Joints.......................................................................................................................11

Figure 4.3 Crack.......................................................................................................................11

Figure 4.4 Pockmarks ..............................................................................................................11

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ABSTRACT

Several countries around the world have used interground limestone cement (ILC) for several years inconcrete construction. The results from various research projects do not all agree on the influence

interground limestone has on the plastic and hardened properties of concrete, but most agree that thevariability can be controlled if the limestone content remains at or below 5%. To better understand theperformance of ILC, a test section of concrete flatwork was poured in a median in Baxter, Minnesota in

October 2004. This test section was constructed with concrete made with and without interground

limestone in the cement. The physical and chemical properties of both cements were very similar. Tests

of the fresh and hardened properties of both concretes placed in the field suggest very similar propertieswith slightly higher strengths for the interground limestone cement. The reason for the increased strength

of the interground limestone is uncertain but may have been related to a reduced w/cm ratio. The test

section is performing well after more than 2 years. Based on this small test section it appears thatmechanical properties similar to normal concrete can be achieved using


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Executive Summary

Grinding raw, natural forming limestone with the clinker during the cement production results in a product

called interground limestone cement. The Canadian Standards have allowed up to 5% limestone in

ordinary Portland cement (OPC) since the early 1980s and several countries around the world allow 1% -5% in their OPC (1). In 2004 ASTM changed C150 Standard Specification for Portland Cement to allowinterground limestone in OPC.

Results from published research disagreed as to the influence of interground limestone on the plastic and

hardened properties of concrete made with and without interground limestone in the cement. Some

research showed that a small addition of limestone to the cement enhances hydration by providingnucleation sites for the hydration process (2), while other research claimed the limestone participates very

little if at all in the hydration process and may lead to slower set times and lower strengths (3). Some

literature indicated that, most of the chemical and physical properties of cement varies more between

plants than between interground limestone cement (at


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These cement tests indicate that the addition of


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Chapter 1

Introduction

Background

Interground limestone cement is made by grinding raw, natural forming limestone with theclinker during the cement production. In recent years there has been concern and much

discussion about accepting < 5% interground limestone cement as ordinary Portland cement

(OPC) in paving and other transportation structures. The Canadian Standards have allowed up to5% limestone in OPC since the early 1980s and several countries around the world allow 1% -

5% in their OPC (1).

In 2004 ASTM changed C150 Standard Specification for Portland Cement to allow interground

limestone in OPC. According to ASTM C150-04 (section 5.1.3) Up to 5.0% limestone by massis permitted in amounts such that the chemical and physical requirements of this standard are

met. Pure limestone is CaCO3, the same material that is often used in the production of cement

clinker. However natural limestone often contains impurities of sand, silt, clay, iron and otherrock and mineral components. C150-04 requires that the limestone used as an addition contain

at least 70% some form of CaCO3. This allows up to 30% of the limestone to be sand, silt,

clay or other natural components, which in turn allows up to 1.5% of these impurities in the

cement (ie: 30% of the 5% is 1.5% of the total cement).

Previous Research

According to Neville (2), some research showed that a small addition of limestone to the cement

enhances hydration by providing nucleation sites for the hydration process. Detwiler and Tennis(3) and Hawkins, et al (1) referenced other research that claim the limestone participates very

little if at all in the hydration process and may lead to slower set times and lower strengths.

The Portland Cement Association (PCA) Sate-of-the Art Reviewsummarized the work of several

researchers some of which had conflicting results (1). Some of the research claimed addinglimestone to the cement has the following effects on the mix:

o decreased the water demando increased workabilityo slight increase in plastic viscosity

o more easily consolidated by vibration

o accelerated hydration rateso reduced strength

o slight increased shrinkage

While other research documented the opposite effects. Details from some of this research

suggested that added limestone reduced the pore volume and connectivity of pores therebyreducing the permeability (1). A slight reduction in oxygen permeability was measured but no

change in porosity or absorptivity was measured. Other work presented in this same publication

looked at the water absorption of concrete made with cements with and without limestone, andresults indicated a greater difference between cements from different plants than between

cements with and without limestone from the same plant. Some problems with scaling and

freeze/thaw durability were documented for some concretes made from cements that contained

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15% or more limestone. However, the durability related to the amount and type of clay in the

limestone and not the percent limestone added (1). Similarly, the sulfate resistance of limestonecement concrete varied and related more to the varying C3A content than the limestone content

(4).

The growth of secondary minerals in the cement paste can cause distress and lead to early

deterioration. Thaumasite is one such mineral, similar to and often associated with the formation

of secondary ettringite. Thaumasite needs a ready supply of sulfates and carbonates (CO3) toform, such as concrete that contains CaCO3dust and is exposed to sulfate rich waters (5).

However, work reported by Hooton and Thomas (6) suggested that 5% limestone addition is not

sufficiently high, but 15%-35% limestone may trigger a problem with thaumasite formation.

Amidst these conflicting reports the Portland Cement Association (PCA) has taken the stand that

the influence of interground limestone in the cement is dependant on the final particle sizedistribution, and the chemistry of the clinker and limestone. These physical and chemical

properties can be optimized with the use of < 5% interground limestone to produce a

comparable, if not slightly enhanced OPC. The current limits for loss on ignition (LOI) andinsoluble residue in ASTM C150-04 provides additional quality control (1).

Research Problem and Goals

By 2004 interground limestone cements were becoming more available in Minnesota. Because ofthe increasing availability and the conflicting reports on the influence of interground limestone in

cement, the Minnesota Department of Transportation (Mn/DOT) became concerned about the

quality of the final concrete product that would be provided for future paving. After severalmeetings with the cement industry Mn/DOT and Holcim ventured into this joint project that

investigated how interground limestone affected:

o workability and placement of the fresh concrete,

o strength developmento long-term durability related to scaling, freeze/thaw durability and paste deterioration

from the growth of thaumasite.

Research Approach

A small concrete test section was placed as a median adjacent to a major highway to helpinvestigate concerns and make recommendations for Mn/DOTs future use of interground

limestone cement. The two parts to this test section included concrete made with OPC without

limestone, and concrete made with interground limestone cement. Other than the cement, thetwo concretes were proposed to be exactly the same, following the same mix design.

A series of tests were established to measure any possible differences between the cement with

and the cement without interground limestone, and the concrete made with each. Cementsamples were sent to Mn/DOTs Materials Office to characterize the physical and chemical

properties of the cements. The slump and percent air of both concretes were measured in the

field during placement of the test section. At the time of placement cylinders, beams and prismswere fabricated in the field and tested for strength and freeze/thaw durability. The field site was

visited more than two years after placement to evaluate its early field performance.

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Chapter 2

Test Section Construction Report

The test section for this project, SP1810-87, consisted of the two concrete mixes placed as the

flatwork for the median of Edgewood Drive just west of the intersection with TH 371,

approximately 1.9 miles north of the intersection of TH 371 and TH 210, Baxter, MN. Both

concretes were batched from Holcim St. Lawrence Cement, from the Mississauga Plant; onebatch contained cement with interground limestone (4.3% by mass) and the other batch

contained cement from the same source, same clinker, but without interground limestone.Bauerly Company in Baxter, MN, for Holcim (US) Inc., tested both concrete batches in

conjunction with the concrete placement for the city of Baxter.

Mix Design

The mix design proposed for the flatwork was a typical Mn/DOT 3A32 Mix and is detailed in

Table 1. A copy of the approved mix design is shown in Appendix A. Both the fine and the

coarse aggregate for this project came from Roberts gravel pit, source #11001, Gull Lake. Thefly ash was a Class C fly ash from North Shore Mining power plant. Copies of the Mill

Certificate for the cement with limestone and the oxide analyses of both cements are discussed in

Chapter 3 and available in Appendix B.

Table 2.1 Mix Design

Mix No. Slump (in.) % AirTotal

CementitiousFly ash w/cm

3A32 2 to 3 6.5 599 lbs 15% 0.48

Cement samples were sent to the Mn/DOTs Office of Materials lab and characterized using

ASTM, AASHTO and/or Mn/DOT standardized tests for: chemical analysis, loss on ignition, set

time (ASTM C191 Vicat and C266 Gilmore), air content (ASTM C185), fineness (ASTM C204Blaine), autoclave expansion (ASTM C151) and compressive strength (ASTM C109 Mortar

cubes). Results are presented and discussed in Chapter 3.

Field Placement

The concrete for this test section was placed on October 21, 2004. Historical weather records

and anecdotal information suggests the weather that day was cool, cloudy and dry (high of 58F

and low of 39F). Two truckloads, each containing seven yards of concrete, were placed as theflatwork of the median of Edgewood Drive. The first truckload was batched using cement that

contained interground limestone and placed as the western half of the median, then the concrete

without interground limestone was placed as the eastern half closest to TH 371 (as shown inFigure 2.1). The words begin test and end test were etched into the soft concrete surface on

either end of the newly placed test section that contained interground limestone cement.

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The target mix parameter was to produce both mixes with equal slump. The contractor tested thefresh concrete from both trucks at the construction site for slump and air content. Results of fieldtests are given in Table 2. The percentage air varied slightly between mixes and was slightly

higher than the mix design (6.5%) for both mixes. Both mixes were placed with equal slump

that was slightly higher than the target mix design (2-3 in). This slight deviation from the mixdesign of slump and air is not considered significant for this project.

Table 2.2 Field Test Results

w/o Limestone w/ Limestone

Slump (in) 3.75 3.75

Air (%) 7.8 6.8

Although only one mix design with a single w/cm ratio (0.48) was approved for use with both

cements, a letter from Mr. Gardiner, Holcim, Jan. 24, 2005, suggested that less water was used in

the mix that contained interground limestone cement to achieve the same slump (see AppendixD).

Specimen Fabrication

The contractor also cast specimens at the field site from each job mix. These specimens werecylinders and beams tested for compressive strength and flexural strength at 1, 7 and 28 days.

The test results are given in Chapter 3, Test Results and Analyses. (Specimen dimensions werenot documented.)

Six concrete prisms also were cast at the site the day of paving, three prisms from each mix, forrapid freeze/thaw testing. The prisms arrived at American Engineering and Testing (AET)

laboratory, St. Paul, MN on October 27, 2004 at which time they were placed in a temperature

controlled 100% moist room until they were 28 days old. At 28 days, the prisms were removed

cement w/o lmst is inwest. The test section without inter round limestone

a) b)

TTHH337711

w/o lmst

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from the moist room and placed in a freezer until there was room in the freeze/thaw chamber in

December 2004. The freezing and thawing testing was conducted according to ASTM C666Standard Test Method for Resistance of Concrete to Rapid Freezing and Thawing,procedure A.

The test results are given in Chapter 3, Test Results and Analyses.

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Table 3.2 Mix Design for 2-in Mortar Cubes

Mix w/o limestone w/ limestone

Cement (g) 500 500

Sand (g) 1375 1375Water (ml) 242 242

w/cm 0.484 0.484

Flow 105 105

Air entrainer 230 230

The fineness of cement influences some of the plastic and hardened properties of the concrete.

An increase in fineness may increase the rate of hydration and strength development, and to a

small extent, the workability of a concrete mix (Neville, 1997). The Blaine is a measure of thespecific surface of the cement particles and gives an accepted measure of the relative fineness of

cements. The Blaine measured for the two cements used in this project, with and without

limestone, were very similar. The slight difference is within ASTM range of acceptability of twotests performed on the same cement. Therefore, it is no surprise that the strength development

and workability (measured as flow) also were very similar for the mixes made from these two

cements.

Chemical Cement Tests

The oxide analyses of the two cements performed by Mn/DOTs lab are very similar, and vary

only slightly from the mill certificate, as shown in Table 3.3. All results are within AASHTO

M85/ASTM C150 Standard Specification for Portland Cement. (See Appendix B for discussionon sulfate content).

Table 3.3 Chemical Analyses of Cement

(%)Mn/DOT Lab

w/o limestone

Mn/DOT Lab

w/limestone

Mill Certificate

w/limestone

SO3 4.32* 4.33* 4.17*

MgO 3.04 3.02 2.26

CaO 62.69 62.40 61.19

SiO2 19.53 19.38 19.07

Fe2O3 2.31 2.38 2.34

Al2O3 4.66 4.81 5.67

NaO 0.45 0.41KO 1.06 1.05

Available Alkali 1.15 1.10 0.87**

C3A 8.44 8.72 11.06

C3S 59.85 58.68 42.02

C2S 10.84 11.30 22.99

C4AF 7.03 7.24 7.13* SO3are higher than recommended for Type I but allowed since expansion remains below 0.02%

** Reported as total alkali

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Hardened Concrete Tests

The hardened concrete test specimens were fabricated on site at the time of construction from the

same mix that was placed in the field. Specimen dimension were not recorded for these tests, but

standard ASTM/AASHTO test procedures were followed using recommended sample sizes. Theresults of hardened concrete tests performed for the contractor are presented in Table 3.4.

Table 3.4 Hardened Concrete Test Results

Compressive Strength


1 Day (psi) 1130 1170

7 Day (psi) 3610 3910

28 Day (psi) 4470 5260

Flexural Strength


1 Day (psi) 265 305

7 Day (psi) 615 675

28 Day (psi) 780 980

ASTM C666 Freeze/Thaw Testing (Individual prism measurements after 319 cycles)


% Weight Loss 0.57 0.50 0.44 0.38 0.39 0.52

% LengthExpansion 0.049 0.042 0.052 0.029 0.034 0.046

% RDM 89 94 91 95 94 92

The concrete made with the interground limestone cement achieved greater strengths than the

concrete made without limestone as shown in the compressive and flexural strengths tests at 1, 7

and 28 days. The contractor suggested that the interground limestone cement required less water

to achieve the same slump and this lower water demand enabled the interground limestonecement to achieve greater compressive and flexural strength while maintaining workability (per

l/24/05 letter from Mr. Gardiner, Holcim (US), Inc. as shown in Appendix D). This information

suggests that the mix made with interground limestone cement was placed using a lower w/cmthan the mix made with the standard cement. A lower w/cm would explain the higher strengths.

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The ASTM C666 Standard Test Method for Resistance of Concrete to Rapid Freezing andThawingtest results for both mixes were very similar, and suggest that both mixes have good

resistance to freezing and thawing deterioration.

Comparing Mortar and Concrete

The strengths of the field concrete made with interground limestone cement were higher than the

concrete made with standard cement. It is difficult to determine how, or if the presence of

limestone in the cement had an influence on this strength increase or on the workability, sinceslump was the only measure of workability (and it remained unchanged) and no records were

available for the as built w/cm or use of water reducers.

Contrary to the concrete strengths, the mortar strengths, tested under controlled laboratoryconditions using the exact same mix proportions, were very similar for both mixes made with

and without limestone in the cement. The workability, measured as flow, was the same for both

mortar mixes. The w/cm was relatively high (0.484) but the same for both mortar mixes and nowater reducers were used.

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Chapter 4

Two Year Performance Review

The field site was visited on January 4, 2007, and the concrete surface conditions examined. The

concrete flatwork in the test section appeared to be in very good condition (figure 4.1). The testsection built with interground limestone cement is easy to distinguish because the words BEGINTEST and END TEST were etched into the wet concrete at the beginning and end of this pour

(as seen in the foreground of figure 4.1a.).

X

Concrete with intergroundlimestone cement

Standard concrete w/o limestone cement

Figure 4.1Concrete test section 2-years later (Jan 4, 2007). Looking west

at the concrete made with interground limestone cement (a) and looking

east at the standard concrete (b).

a) b)

The joints were of average width, not compressed, and in good condition (figure 4.2). There

were a few pop outs in both the interground limestone cement concrete and the standard concrete

sections. Popouts were rare, cover only a small area of the concrete surface, probably will notaffect the durability of the concrete, and are more related to the aggregates used and not to paste

properties. The number of pop outs was similar in both the limestone cement concrete and

standard concrete sections.

There was a crack at the east end of the median near TH 371, in the standard concrete section (as

noted by an X in figure 4.1). This single crack appeared to be more structural in nature and

probably not materials related (see figure 4.3).

There were some very shallow pockmarks on the concrete flatwork surface on the east end of the

project, in the concrete that contained standard cement. These pockmarks, as shown in figure4.4, are very shallow, do not look fresh and look similar to raindrop impressions. No additional

distress is associated with the pockmarks.

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The cause of the pockmarks is not clear. The appearance is not flakey, fresh or deep as scaling

usually appears. Doug Schwartz, Mn/DOTs Concrete Engineer, has seen similar distresspatterns in which finishing and/or curing problems resulted in mortar flaking after being exposed

to freezing and thawing.

Figure 4.2 Jointsare in good

conditionsFigure 4.3 Crack -located near the eastern end of the

If fresh concrete is exposed to a hard rain or hail while the strengths are low and the surface not

yet hard, it could leave pockmarks such as these. The pockmarks are only in the east end of the

project which was the last section poured. A web-based search of the National Climate Data

Center for 2004 indicates that there was no rain recorded the day this project was poured, 0.06inches recorded the following day and 0.60 inches of rain the second day after pouring the

concrete. Hail was recorded approximately 50 miles away on October 23, 2004, the second dayafter the concrete was poured. Storms, tornados and hail were reported in several areas around

the state on October 29, 2004, eight days after the concrete was poured. The temperatures at the

time of placement and in the days that followed would have influenced the set time and strength

gain (see table 4.1). Cement hydration can be significantly slower at 40F resulting in strengths

that may be half to a quarter of strength typical for concrete cured at 70F (7).

project as located by the X in figure 4.

Figure 4.4Pockmarkson the concrete surface.

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Table 14.1 Daily temperatures

Date

Maximum

Temperature

F (C)

Minimum

Temperature

F (C)

10/21/04 58 (14) 39 (4)10/22/04 49 (9) 44 (7)

10/23/04 62 (17) 48 (9)

10/24/04 59 (15) 33 (1)

10/25/04 54 (12) 35 (2)

10/26/04 53 (12) 35 (2)

10/27/04 51 (11) 36(2)

10/28/04 47 (8) 39 (4)

Overall the concrete appears to be in very good condition. The pop-outs and pockmarks at this

time are no cause for concern other than esthetics. The cracked area should be monitoredperiodically for additional cracks, progressive deterioration associated with the crack and/or loss

of integrity of the concrete in that area. Otherwise, more than two years after placement, there is

nothing apparent from the surface survey that indicates either the limestone cement test sectionor the control section may have durability problems. The performance of the concrete that

contained 4.3% interground limestone in the cement is comparable to the standard concrete.

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Chapter 5

Summary and Conclusion

Summary

The literature indicates that most of the chemical and physical properties of cement varies morebetween plants than between interground limestone cement and cement without interground

limestone from the same plant. The chemical and physical properties of the two cements tested inthis project were very similar. The set time, fineness test and compressive strength test results of

the two cements fell within the standard deviation considered acceptable by ASTM for testing

the same material. These similarities suggest that the differences between the two cements arenot significant.

The measure of workability for both the mortar (flow) and the concrete (slump) for mixes made

with these two cements were similar. In contrast, although the of strength gains measured for the

two mortars were similar, the strength gains for the two concretes were not. The concrete made

with interground limestone cement had higher strength than for the concrete made with thecement without limestone. The mortar samples were fabricated and tested in controlled

laboratory conditions. The concrete was fabricated in a batch plant and tested in the field.

The contractors goal for field placement of the two mixes was similar slump; therefore the w/cmmay not have been constant between the two mixes. There is some evidence that suggests the

interground limestone cement concrete was fabricated with a lower w/cm, which would explain

the higher strengths. At the time this report was written there were no documentation available

that identified any adjustments were made to the approved mix design. Other than a letter fromthe cement producer, it cannot be concluded if the interground limestone cement was placed with

a lower w/cm, if interground limestone contributed to improved workability or if interground

limestone was the factor that contributed to increased strengths.

The field placement of both concretes went smoothly without any unusual problems with eithermix. The laboratory-conducted tests suggested adequate strengths and good freeze/thaw

durability of both concretes. The appearance and performance of the test section after more than

two winters is excellent. There are no indications of early distress or other problems other than

minor flaking of the mortar that appeared as pockmarks on a small area of the non-limestonecement concrete.

Conclusions and Recommendations

Based on the cement and concrete tests, the concrete placements and the two-year performance

of the test section it appears that the addition of 4.3% limestone, interground with the cement,resulted in cement that had similar properties to cement without interground limestone. Also, the

concrete made from cement that contained 4.3% interground limestone had similar plastic andhardened properties to the concrete made with OPC without interground limestone, with little to

no adjustments to the mix design. The long-term durability of the concrete is yet to be

determined in the field, however laboratory tests and the 2-year performance suggest that thepotential for long-term durability is good.

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It is recommended that monitoring of the test section continue with a site visit and surface

evaluation every 3-5 years. If surface conditions indicate possible materials related distress then

cores should be taken and a petrographic analysis and other appropriate tests performed todetermine the cause and extent of the problem.

Future paving using cement that contains less than 5% interground limestone cement may not be

a problem, as long as the cement continues to meet the ASTM C150 standards and Mn/DOTs

requirements. ASTM C150-04, section 12.2 requires that when limestone is added to the cement

that the manufacturer shall state in writing the amount of limestone used in the cement. Based onthis research project and research documented in the literature it is advised that all future

Mn/DOT projects be identified and recorded in which interground limestone cement is used, and

that the mill certificates for the cement remain on file.

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References Cited

1. P. Hawkins, P. Tenis and R. Dewiler, The Use of Limestone in Portland Cement:A State-of-the-Art Review, Engineering Bulletin 227 (Skokie, IL: Portland Cement Association,

2003).

2. A. M. Neville, Properties of Concrete: Fourth and Final Edition(New York, NY: John

Wiley & Sons, Inc, 1997).

3. R. Detwiler and P. Tennis The Use of Limestone in Portland Cement: A State-of-the-Art

Review, PCA R&D Serial no. 2052a (Skokie, IL: Portland Cement Association, 1996).

4. D. R. Hooton, Effects of Carbonate Additions on Heat of Hydration and Sulfate

Resistance of Portland Cement, Carbonate Additions to Cement, ASTM STP 1064, P.Klieger and R.D. Hooton, Eds. (Philadelphia, PA: American Society for Testing and

Materials, 1990) pp 73-81.

5. D. A. St. John, A. W. Poole and I. Sims, Concrete Petrography: A handbook of

investigative techniques,New York, NY: John Wiley & Sons, Inc., 1998).

6. R. D. Hooton and M. D. A. Thomas, The Use of Limestone in Portland Cement: Effects

on Thaumasite Form of Sulfate Attack, PCA R&D Serial no. 2658 (Skokie, IL:Portland Cement Association, 2002).

7. S. H. Kosmatka, B. Kerkhoff and W. C. Panarese,Design and Control of Concrete

Mixtures: Fourteenth Edition(Skokie, IL, Portland Cement Association, 2002).

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Appendix A

Concrete Mix Design

A-1


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A-2


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A-3


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Appendix B

Cement Properties


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Discussion on sulfate levels in cement

Typically the sulfates (reported as SO3) are kept below 3.00% for Type I and 3.50% for Type III

cements however, if C3A is greater than 8%, as it is here, sulfates can be as high as 3.50% for

Type I and 4.50% for Type III cements. * SO3are higher than recommended for Type I but is

allowed per ASTM C150 Standard Specification for Portland Cementas long as strength is notcompromised and expansion remains below 0.02%. Both the higher sulfate and C3A content

may reduce the sulfate resistance of concrete made with these cements. The sulfate level is not

affected by the presence of limestone in the cement.

Variability in Strength

B-1


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B-2

Figure B. 1. Mill Certificate of cement with interground limestone.


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Figure B.2. Properties of cement without interground limestone.

B-3


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B-4

Figure B.3. Properties of cement with interground limestone.


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B-5

Figure B.4. Oxide analysis of cement without interground limestone.


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B-6

Figure B.5. Oxide analysis of cement with interground limestone.


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Appendix C

ASTM C666 Freeze/Thaw Test Result


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C-1


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C-2


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C-3


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Appendix D

Testing Summary Provided by Holcim


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January 24, 2005

Doug Schwartz, PE

Mn/DOT Office of Materials

1400 Gervais Ave.

Maplewood, MN 55109-2044

Dear Mr. Schwartz:

Re: Testing Summary of Cement with Limestone

This letter is a summary of the testing conducted in Baxter for the St. Lawrence Cement that contained

interground limestone. This testing was conducted in conjunction with a concrete placement for the city

of Baxter. The control cement without interground limestone was also tested to provide a baseline

comparison.

Work Scope

Two seven yard of truck loads of concrete were placed in the median of Edgwood Drive at the

intersection Highway 371. The first truck was batched using cement that contained interground

limestone and the second contained cement from the same source without interground limestone. The

section of median is presented in Photographs No. 1 and 2.

Photograph No. 1, Median placed during test,

looking east.

Photograph No. 2, Median placed during test,

looking west.

D-1


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D-2


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2007interground limestone and cement

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