very-high-strength concretes for use in blast- and penetration

8/9/2019 Very-High-Strength Concretes for Use in Blast- And Penetration

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QUARTERLYVolume 6, Number 4

A M P T I AC i s a DOD Information Analysis Center Administe red by the Defense Informatio n Systems Age n c y, De fense Te chnical Informatio n Cen ter and Opera ted by Ali on Science and Te ch n o l

SpecialIssue:

P ro t e c t i n gPeople at Risk:

How DOD Research Reducesthe Impact of Terrorism


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Issue focus:How DOD Research ProtectsPeople and Buildings

US Government Initiatives Reduce Terrorist Threat to Personnel and Structures 5Wade Babcock and David Rose, AMPTIAC, Rome, NYThe US Government has been addressing the issue of protecting people and stru ctures from terrorist attacks for many years. Thisarticle provides an introduction to the federal coordinating group which directs these activities, and the DOD agency that focuseson military issues. This article also features insight from some of the key people within DOD who direct and take part in these efforts.

The TSWG Closeup 8

Protecting Personnel at Risk:

DOD Writes Anti-Terrorism Standards to Protect People in Buildings 11Colonel Joel C. Bradshaw III, PE, Chief of Military Construction Programs, Office of Deputy Under Secretary of Defense(Installations and Environment), The Pentagon, Washington, DC

The DOD takes the issue of protecting its personnel very seriously and has recently completed the codified anti-terrorism stan-dards which began a few years ago as guidance and interim directives. Colonel Bradshaw is in a unique position to explain someof the critical steps and policy issues that drove this process, as well as the top-level directives and initiatives that are contained inthe document.

DOD Protective Design Manuals Have Wide Application 17Patrick Lindsey, PE, Protective Design Center, US Army Corps of Engineers, Omaha, NEFactors such as site selection, building location on the site, use of fences and clear space, as well as vegetation and structural rein-forcements are all critical to protecting a building and its occupants from various threats. Incorporating protection into a facilitysdesign is the best way to achieve a desired level of protection at a reasonable cost. Patrick Lindsey of the Protective Design Centersummarizes many of the key features and considerations to be accounted for, and introduces the DOD resources available.

Homeland Security vs. Homeland Defense Is there a difference? 24

Polymer Composite Retrofits Strengthen Concrete Structures 25Robert Odello, Director, Waterfront Structures Division, Naval Facilities Engineering Services Center, Port Hueneme, CAThe Navy is using composite materials to strengthen pier decks and support columns. Some of these structures were not designedfor current load requirements and therefore need to be upgraded while others are deteriorating and the retrofits can bring themback to full service. The systems outlined in this article are also being considered for use in buildings to increase both dynamicshock-induced load capability and the ability to withstand negative loading. Robert Odello describes a program that is proving thatcomposite systems offer viable, serviceable, and cost effective ways of strengthening real-world concrete structures. These programsare also educating both the government and industry on how to specify, install and maintain them. Lessons learned in these Navyprojects will help further advance the protection and hardening of land-based structures.

Blast Retrofit Research and Development:Protection for Walls and Windows 31

David Coltharp and Dr. Robert L. Hall, Geotechnical and Structures Laboratory, US Army Corps of Engineers,Engineer Research and Development Center, Vicksburg, MSConventional building components are highly vulnerable to terrorist vehicle bomb attack. Common annealed glass windows breakat very low blast pressures and the resulting flying glass fragments are a major cause of injuries in many bombing incidents. Masonryin-fill walls are also weak elements and another source of hazardous debris. Through the combined research and development effortsof multiple DOD agencies and the State Department, significant advances have been made since 1996 in improving methodsfor protection of conventional military and government facilities. David Coltharp presents some of the unique and innovativemethods that have been developed for retrofitting windows and walls, and describes how they increase the blast capacity of thesevulnerable components, decrease standoff requirements, and improve protection for personnel.

Mark Your Calendar 38

The AMPTIAC Quarterly, Volume 6, Number 4

A M P T I AC is a DOD Information Analysis Center Administe red by the Defense Information Systems Age n c y,D e fens e T e chnic al Infor mati on Cente r and Ope ra ted by Alion Scien ce and Te ch n o l o g y


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MaterialEASE: Materials for Blast and Penetration Resistance 39Richard Lane, Benjamin Craig, and Wade Babcock, AMPTIAC, Rome, NYIn 2001 AMPTIAC was tasked by the Office of the Secretary of Defense to summarize the research efforts and data compiled onblast and penetration resistant materials (BPRM), including monolithic materials and novel combinations of materials. As aservice to the uninitiated, we have provided this primer so that those less familiar with material and security matters maydevelop a well-rounded perspective of the topic. In turn, this may afford you, the reader, a greater appreciation of the relevance andimportance of the topics discussed within this issue of theAMPTIAC Quarterly.

Polymer Coatings Increase Blast Resistance of Existing and Temporary Structures 47Dr. Jonathan Porter and Robert Dinan, Materials and Manufacturing Directorate, Air Force Research Laboratory, Tyndall AFB, FLDr. Michael Hammons and Dr. Kenneth Knox, Applied Research Associates, Inc.The DOD has banned the use of selected concrete masonry infill building techniques because they dont hold up to blastoverpressures and present a serious risk to occupants in the event of a blast. Additionally, the extensive use of temporary, portablestructures presents another unique blast protection problem. This Air Force program is looking for ways to retrofit these thousandsof structures in a quick and cost effective manner, while adding a significant level of fragmentation protection.

Designing Blast Hardened Structures for Military and Civilian Use 53Bruce Walton, PE, Protective Design Center, US Army Corps of Engineers, Omaha, NECenturies ago castles and moats addressed the need to keep a facility safe from an attacker. From those massive stone and woodstructures, to the hardened reinforced concrete and sophisticated intrusion detection systems of the present, the principles ofhardened structures have fundamentally remained the same: Identify the baseline threat and keep it at a safe distance, or create astructure as impervious as possible to that threat. Bruce Walton provides a broad, overall perspective on the problem of designing

a hardened structure, and describes some of the techniques, fundamentals, and resources available.

Design Example Exterior Blast Upgrade 56

IAC Program Addresses Homeland Security 60

Very-High-Strength Concretes for Use in Blast- and Penetration-Resistant Structures 61Dr. J. Donald Cargile, Impact and Explosion Effects B ranch; Ed F. ONeil and Billy D. Neeley, Concrete and Materials Division;Geotechnical and Structures Laboratory, US Army Corps of Engineers, Engineer Research and Development Center, Vicksburg, MSYou may be thinking that there is nothing we can tell you about concrete that wont cure insomnia, but youd be wrong. How doesadvanced concrete 4 to 5 times stronger than standard concrete sound? The folks at ERDC are working to drastically improve thisubiquitous material, both in its general compressive strength and its resistance to fragmentation in impact events. Donald Cargileand his colleagues present the experimental data and demonstrate that concrete has a lot of development potential left in it.

The AMPTIAC Quarterly is published by the Advanced Materials and Processes Technology InformationAnalysis Center (AMPTIAC). AMPTIAC is a DOD sponsored Information Analysis Center, operatedby Alion Science and Technology and administratively managed by the Defense Information Systems Agency(DISA), Defense Technical Information Center (DTIC). The AMPTIAC Quarterly is distributed to morethan 25,000 materials professionals around the world.

Inquiries about AMPTIAC capabilities, products and services may be addressed toDavid H. Rose

Director, AMPTIAC

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E M A I L : a mp t i a c @ a l i o n s c i e n c e . c o mU R L : h t t p :/ / a mp t i a c . a l i o n s c i e n c e . c o m

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CLARIFICATION: The cover story for our last issue described the Armys exciting Mobile Parts Hospital project. Within thatarticle, a technology called Laser Engineered Net Shaping was presented which can fabricate replacement parts using acombination of computational design templates, a computer-controlled laser, and powder metallurgy. Laser Engineering NetShaping and the LENS acronym are registered trademarks and service marks of Sandia National Laboratories andSandia Corporation.


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INTRODUCTIONMost fixed protective structures employ concrete in some way.The US Army Engineer Research and Development Center(ERDC) is conducting research to provide force protection ineverything from foxholes to fixed facilities and against threatsranging from small arms to advanced conventional, and eventerrorist weapons. Concrete is a highly economical material, itcan be cast into many shapes, and can be formulated for vary-ing degrees of strength and durability. It is primarily used for itscompressive strength, as concrete is much stronger in compres-sion than it is in tension. With the proper use of tensile re-inforcement, concrete can be used in many tensile-loadedapplications, such as flexural members, eccentrically loadedcompression members, and direct tension members.

Because of the wide use and availability of concrete, it is use-ful to elaborate on its fundamentals. Additionally, a betterunderstanding of the complex creation of concrete variants willassist engineers and architects in choosing the best materials thataddress aesthetic, engineering, and protective considerations.

ADVANTAGES OF HIGHER STRENGTH CONCRETE ANDITS APPLICATION TO STRUCTURAL PROTECTIONThe variability of concretes strength and mass make it a usefulmaterial in structural protection. The mass of a concrete mem-

ber can be varied by altering its component materials andgeometry. For applications where ample mass is needed, a largesection of normal-density concrete or a smaller section of high-density concrete can be used. For applications where mass orsize is detrimental, yet strength is necessary, concrete structurescan be designed with thin sections of higher-strength concrete.

Engineers are constantly looking for new materials to provideanswers to complex problems. As construction and materialcosts escalate, demand has increased for stronger materials thatoccupy less space. Research has been examining high-perform-ance concrete materials for use in protective structures [1-4].

Developments in very-high-strength concrete (VHSC) [5-8], amaterial made using conventional constituents combined incritical proportions, have further expanded these capabilities.

Limitations of Conventional ConcreteUnreinforced concrete is inherently brittle, having very littlecapacity for inelastic deformation before failure. It is also veryweak in tension. Under compressive loading, it exhibits linearelastic behavior until initiation of first cracking of its matrix. Asloading continues above this point, concrete exhibits increasednon-linear plastic deformation for a short time before ulti-mately failing in a brittle manner.

The unconfined (concrete with no exterior covering such asa steel sleeve) compressive strength of conventional concrete isgenerally less than 41 MPa. Concretes with design strength incompression greater than 41 MPa are called high-strength.High-strength concrete having design compressive strength of100 to 125 MPa is available in many areas. The tensile strengthof most concrete generally does not exceed 10% of the com-pressive strength (i.e. approximately 4 to 10 MPa). VHSCdoes not follow this proportional relationship however, as itstensile strength is often no higher than 10 MPa. For use as aprotective material, both tensile and compressive strength areimportant properties. From a ballistic point of view, they are

important in resisting the cratering and break-up of thestructure caused by projectile penetration and, in many cases,detonation of a weapon.

VHSC PrinciplesVHSC is made from the same general constituents as conven-tional concrete (cementitious material, water, aggregate, andadditional compounds for removing air and water from the mix{admixtures}). Yet, the careful selection of constituents andtheir proportions, as well as proper mixing, results in signifi-cantly improved tensile and compressive strength, toughness


Dr. J. Donald Cargile,Impact and Explosion Effects B ranch;

andEd F. ONeil and Billy D. Neeley,Concrete and Materials Division;

Geotechnical and Structures LaboratoryUS Army Corps of Engineers

Engineer Research and Development Center(formerly Waterways Experiment Station)

Vicksburg, MS


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and durability, as well as reduced water permeability. The phys-

ical and mechanical properties can be further improved by theapplication of heat and pressure during the casting and curingstages of hydration. The principles used in producing VHSCare listed in Table 1. Some significant differences from conven-tional and high-strength concrete are:

size and composition of constituents ratio (by weight) of water-to-cementitious material (w/cm) the use of steel fibers (sometimes micro-fibers) to improve

ductility and toughness the amount of mixing energy employed curing procedures used

Conventional concrete is a very heterogeneous material withcomponents from fine cement to coarse aggregates, each

exhibiting different strengths and modulii of elasticity. Under asystem of forces, all these component materials deform at dif-ferent rates. The differential movement of these componentsproduces strains between the component materials that beginthe process of tensile fracture when the strains exceed the ten-sile strain capacity of the concrete. Concrete such as VHSC iscomposed of particles of similar modulii and size, which helpsincrease the homogeneity of the composite material therebyreducing the differential tensile strain in the concrete andincreasing the ultimate load-carrying capacity of the material.

High density* is the second principle employed to increasestrength and decrease permeability. In choosing the volumes

of component materials, particle-packing techniques can beused to maximize the amount of solids per unit volume of con-crete. As with conventional concrete, the material having thelargest particle size in VHSC is the aggregate. In VHSC thataggregate is sand whose particle size is limited to a maximum of4.75 mm. The material having the next largest particle size isthe cement, which is on the order of 10 to 100 m. The small-est particles are silica fume, which are on the order of 0.1 min diameter. The component volumes of all these particles arechosen to achieve the greatest particle packing, and hence thegreatest density of the paste. The higher the density, the greater

the strength of the paste and the lower the permeability because

there are fewer and smaller voids.Strength of VHSC is further improved by increasing the vol-ume of pozzolanic components (fine siliceous or aluminouspowders) that can react to form hydration products. In VHSC,materials with a high silica content are necessary for optimumperformance. Cements that are high in silica content (such aslow-carbon silica fume [6]) produce higher strengths. Thesematerials provide chemically active silica that helps to producelarger volumes of calcium-silicate-hydrate (CSH), bonding theother component materials together. High amounts of CSHincrease the strength of the binder and improve the bondbetween the cement and the aggregate.

To optimize performance, the w/cm ratio in VHSC must be

carefully controlled. Excess water in the mixture is detrimentalto the strength of concrete. The quantity of water required tohydrate all of a given amount of Portland cement is about thatpresent at a w/cm ratio of 0.4. Water that is not chemically orphysically combined in the hydration or pozzolanic reaction,

weakens the paste and thus the compressive and tensile strengthof the concrete. The volume of water used in VHSC is kept lowto insure that there is no excess. This volume is less than thatneeded to hydrate all the cement so as to insure that all water isconsumed in the hyd r a t i o n / p o z zolanic reaction pro c e s s .However, this small quantity of water usually does not providesufficient workability to the mixture. High-range-water-reduc-ing admixtures (HRWRA) are used to make the otherwise verystiff concrete flowable.

All these mixture principles combine to produce concretewith an ultimate compressive strength up to approximately 175M Pa, when mixed and cured at ambient temperature s .Strengths greater than 200 MPa can be achieved when the con-crete is cured at 90C for a few days. The processes of addingpressure sufficient to expel any excess liquids and air from thefresh mixture during the casting operations, and providing acuring environment of up to 400C, can produce concrete witha compressive strength greater than 800 MPa.

Figure 1. Flexural-toughness Comparison for VHSC Concrete vs.

Plain and Fiber-reinforced Concrete.

Table 1. Principles of Very-High-Strength Concrete.

Improved homogeneity through particle size andmaterial selection.

Increased density by optimization of particle sizeand mixing technology.

Improved strength by maximizing reactive materialsand minimizing water content.

Increased microstructure by application of pressurebefore setting and post-set heat treatment.

Increased tensile strength, toughness, and ductility byincorporation of steel fibers or steel micro-fibers.

3 Point Bending Test

Plain Concrete

Fiber Reinforced Concret

VHSC

Loading data based on 150- x 150- x 450-mm beams

280

210

140

70

00 0.25 0.50 0.75 1.00 1.25

Deflection, mm



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Tensile PropertiesThe tensile strengths of VHSCs can be higher than those ofc o n ventional concretes. As mentioned pre v i o u s l y, tensilestrength of VHSC may nominally be only 10 MPa, while itscompressive strength is on the order of 180 MPa. The additionof steel fibers increases the first-crack load, increases the ulti-mate load-bearing capacity, and dramatically increases the flex-ural toughness.

Very-high-strength concretes exhibit near-linear stress-straincharacteristics up to failure when fabricated without the addi-tion of fibers. Their fracture energy, defined as the area beneaththe load-deflection curve, is somewhat less than 140 J/m2. Theaddition of fibers to the matrix improves the behavior of the

concrete in the post-first-crack region of the load-to-failurecycle. In VHSC, various percentages and types of steel fibershave been used but the best overall results (incorporating costconsiderations) have been obtained with hooked-ended, steelfibers 30 mm in length and 0.5 mm in diameter.

The large number of small fibers which cross the path ofpotential cracks, coupled with the good bond between fiberand matrix, provide high resistance to fiber pullout during ten-sile-cracking, and greatly increase the toughness of the materi-al. Figure 1 shows the load-deflection curve of a typical VHSCbeam. By comparison, a load-deflection curve for a conven-tional concrete and a conventional fiber-reinforced concrete are

added. Comparison of the areas under the curves gives a rela-tive relationship for the increase in toughness afforded by thevery-high-strength concrete. The greatest effect is in the area ofthe curve beyond the first-crack load, where the samples load-deflection behavior transitions from linear to non-linear. Upuntil this load, the tensile-carrying-capacity of the concrete hasbeen responsible for the shape of the curve. In the unreinforcedconcrete, the magnitude of the first-crack load is about one-tenth that of the VHSC and the load and deflection of thepost-first-crack portion of the curve is very small. Likewise,even with conventional fiber-reinforced concrete the first-crack

strength is lower than VHSC and the post-first-crack portionof the curve is also smaller.

Toughness is a measure of the amount of energy that must beexpended to open cracks in the matrix under tensile loading.An example of toughness would be the resistance to a projectilepassing through a material. This toughness is important in theperformance of protective structures. The amount of energy

required to penetrate the VHSC concrete will be greater thanthat required to penetrate conventional concrete. This meansthat some projectiles will be less effective at penetrating thestructure, and perhaps will even be stopped by the VHSC. Ifthe projectile completely passes through the VHSC, the exitvelocity will be lower than that through the same mass of con-ventional concrete. Also, the amount of material fragmentedfrom the back of a protective-structure member as the projec-tile passes through (also called spall) will be reduced by thesteel fibers in the VHSC matrix.

Penetration ExperimentsNormal impact experiments studying depth-of-penetrationversus striking velocity we re conducted with VHSC concre t etargets. The experiments evaluated the resistance of VHSC topenetration by a robust projectile (one that should notdeform significantly). The VHSC mixture pro p o rtions, as well as those for conve nt io na l - s t rength portland cement(CSPC) concrete, high-strength portland cement (HSPC)c o n c rete, and high-strength, steel-fiber rei nf o rced (HSFR)c o n crete, are given in Table 2. (The mixture pro p ortions inTable 2 provide the req u i red masses of constituents in ord e rto produce roughly one cubic meter of finished concre te .)

Table 2. Concrete Mixture Proportions (kg/m3).

Material CSPC HSPC HSFR VHSC*

Type I Portland Cement 328 546 459 24

Silica Fume 0 71 59 13**

Class F Fly Ash 0 119 59 0

Coarse Aggregate 1034 817 520 0

Sand 806 0 451 0

Limestone Fine Aggregate 0 657 469 40

Water 187 166 171 17

Water Reducing Admixture 1.7 0 0 0

High Range Water 0 12 6 3Reducing Admixture

Air Detraining Admixture 0. 3 1 0.6 0

w/cm 0.57 0.22 0.3 0.18

Fibers 0 0 158 3

* Mixture proportions for VHSC are given in % by volume.

** In VHSC, 8% is silica fume and 5% is silica flour (crushed quartz)

Water reducing admixture given in l/m 3

Figure 2. Drawing of Armor-Piercing Projectile.

Case Material: 4340 SteelMass: 0.906 kg

CG Location: 128.5 mm from nose

242.4 mm

206.8 mm

26.9 mR = 53.6 mm

35.6 mm


Table 3. Hardened Material Properties.

CSPC HSPC HSFR VHSC

28-day Compressive 35 104 85 157Strength, (MPa)

Compressive Modulus 34.5 45.2 45.2 46of Elasticity, (GPa)

56-day Tensile 3.5 4.8 4.5 9.0Strength, (MPa)

Tensile Modulus 44 39.5 39.6 of Elasticity, (GPa)


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The concrete for the targets was placed into corrugated, gal-va n ized-steel culve rts measuring approximately 762 mm indiameter by 914 mm in length. The culve rts we re wrapped ininsulation to maintain heat during curing. Curing of the tar-gets consisted of ponding water on the top of the targets for7 days and then continuing the curing in ambient conditionsuntil the time of the penetration experiments. The penetra-tion experiments and at least two unconfined-compre s s io ntests on samples of the concrete we re conducted on approx i-mately the same day. The age of the concrete at the time ofthe penetration experiments ranged from 30 to 60 days.

The 0.906-kg projectiles were machined from 4340-steel

rods and heat treated to a hardness of 43-45 on the Rockwell Cscale. Each projectile had an ogive nose, a shank diameterof 26.9 mm and an overall length of 242.4 mm as shown inFigure 2. At the time of the penetration experiments, thetargets were placed on their sides, still in the metal-culvertforms, and centered on the longitudinal axis of the gun. Theprojectiles were launched into the targets using the ERDC(formally WES) 83-mm, smooth-bore powder gun [9] at strik-ing velocities (Vs) ranging from 229 m/s to 754 m/s.

Depth of penetration (P) in calibers (penetration depth/projectile diameter) for the experiments into VHSC are comparedto results from penetration experiments into a CSPC concrete[10], HSPC concrete [10], and HSFR concrete [11], as shown

in Figure 3. The experiments into the CSPC, HSPC, and HSFRconcretes used projectiles with the same mass and dimensions asthe projectile used for the experiments into the VHSC concrete.Target fabrication for the CSPC, HSPC, and HSFR experi-ments was similar to that for the VHSC concrete except that thetargets were approximately 1.37 m in diameter. The averageunconfined compressive strengths of the VHSC, CSPC, HSPC,and HSFR concretes used to fabricate targets in these tests were159, 35, 104, and 90 MPa, respectively. Typical compressivestrength values for VHSC can be higher, on the order of 185M Pa, depending on the materials and processing used.

Additional material property data are presented in Table 3.Also in Figure 3, results from the penetration experiments are

compared to depth of penetration which was calculated using aspherical-cavity expansion model developed by Forrestal andTzou [12]. The model separates the target response into elastic,cracked, and plastic (EKP) regions, with the plastic regionbeing closest to the projectile. The target is described bydensity, yield strength, slope of the yield surface, tensilestrength, and linear bulk modulus. The tensile strength of thematerial determines the influence of the cracked region on thedepth of penetration. Values for these model parameters weredetermined for each concrete based on referenced data [2, 4,

13]. The results from the cavity-expansion calculations agreewell with the experiment results (see Figure 3).

Another model presented by Forrestal and Tzou separates thetarget response into elastic and plastic (EP) regions only. Thismodel was used to illustrate the influence of the cracked regionon the depth of penetration[12]. Results from the two modelsare compared in Figure 4. Use of the EP model results in lessdepth of penetration than the results from the EKP model. Theinfluence of the cracked region is greatest for the higher-strength concretes. Results from the calculation using the EPmodel represent a limit to the depth of penetration that couldbe expected as the tensile-yield strength approaches the com-pressive-yield strength.

The depth of penetration from experiments into the HSPCand HSFR concretes was about 30% less than that from exper-iments into the CSPC concrete, while the penetration depthobserved in VHSC is about 50% less. So, one could expectapproximately a 50% reduction in penetration by using theVHSC concrete versus conventional concrete. Post-test photo-graphs of the target faces in Figure 5 show the visible damageto the targets for experiments at a striking velocity of about 800m/s. The amount of visible damage to the HSPC concretetarget is about the same as that for the CSPC concrete target,even though the depth of penetration is about 30% less. The

Figure 4. Comparison of Calculations Using the Elastic-Cracked-Plastic (EKP) and Elastic-Plastic (EP) Versions of the Spherical-cavity

Expansion Model.

Figure 3. Comparison of Penetration Experiment Results and

Spherical-cavity Expansion Model Calculations for CSPC, HSPC,HSFR, and VHSC Concretes.

Data Model

CSPC

HSPC

HSFR

VHSC

100 200 300 400 500 600 700 800 900

Striking Velocity, m/s

40

30

20

10

0


CSPC

HSPC

HSFR

VHSC

100 200 300 400 500 600 700 800

Striking Velocity, m/s

40

30

20

10

0

EKP

EP

EKP

EP

EKP

EP


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addition of steel fibers in the HSFR concrete resulted in asignificant decrease in visible damage, and still resulted in adepth of penetration about 30% less than the CSPC concrete.The visible damage to the VHSC concrete target is comparableto the damage to the HSFR concrete target.

CONCLUSIONSThese new VHSCs are useful for force protection and infra-structures in need of blast and penetration resistance. Theirp e rformance, especially in spall resistance and increased

deflection without failure, mesh well with design requirementscalling for reduced flying debris in buildings and prevention ofprogressive collapse.

Development of this new class of very-high-strength con-cretes, based on use of small-particle component materials andparticle-packing theories, has led to materials with improvedpenetration resistance. Although the direct-tensile strengthsremain low at approximately 10 MPa, the compressive strengthsof these concretes are very high, near 200 MPa. Additionally,the flexural toughness of the concrete is greater than 250 timesthat of conventional, non-fiber-reinforced concrete.

Penetration-resistance experiments conducted on the VHSCindicated approximately 50% less penetration than into CSPCconcrete, and 30% less penetration than into HSPC and HSFRconcrete. Inclusion of fibers into these concretes does notsignificantly improve the penetration resistance of a givenstrength of concrete, but does provide for greater resistance tovisible damage surrounding the penetration crater. Resultsfrom calculations using the spherical-cavity expansion model with elastic-cracked-plastic regions agreed well with theexperimental results.

REFERENCES[1] J.D. Cargile, and L.E. Tidwell, Penetration of a SubscaleSemi-Armor-Piercing Projectile into Conventional-Strength andHigh-Strength Concrete Targets,Technical Report SL-93-2, US Army Engineer Waterways Experiment Station, Vicksburg,MS. 1993[2] M.I. Hammons, B.D. Ne e l e y, and D.M. Sm i t h ,Development and Characterization of Fiber-Reinforced and Slag-Binder Concrete Mixtures for Projectile-Penetration Studies,Technical Report SL-92-16, US Army Engineer Waterways

a. CSPC concrete b. HSPC concrete

c. HSFR concrete d. VHSC concrete

Figure 5. Front-face Damage to Targets Impacted at Approximately 800 m/s.



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Experiment Station, Vicksburg, MS. 1992[3] B.D. Ne e l e y, and D.J. Frew, De velopment andC haracterization of a High-Strength, Hig h-Density Nylon Fib e rRein forced and Sl u rry - Inf i ltra te d- Mat Concrete for Pro ject i lePenetration St u die s, Technical Report SL-95-17, US ArmyEngineer Wate rways Experiment Station, Vicksburg, MS.1 995[4] B.D. Ne e l e y, M.I. Hammons, and D.M Sm i t h ,Development and Characterization of Conventional Strengthand High-Strength Portland Cement Concrete Mixt ures forProjectile Penetration Studies,Technical Report SL-91-15, US Army Engineer Waterways Experiment Station, Vicksburg,MS. 1991[5] W.M. Dowd, and E.F. ONeil, Development of Re a cti vePowder Concrete (RPC) Precast Products for the USAMarket, in: Proceedings, Fourth International Symposium onthe Utilization of High-Strength/High-Performance Concrete, F.de Larrard, and R. Lacroix, eds. Presses de lcole Na t ionaledes Ponts et Chausses, Paris, FRANCE, 29-31 May 1996, pp13 91-139 8[6] B.D. Neeley, and D.M. Walley, VHS Concrete, The

Military Engineer, vol. 87, (572), (1995) 36-37[7] E.F. ONeil, Reactive Powder Concrete: A Very-High-Performance Concrete Material, in: Proceedings, Corps of Engineers Structural Engineering Conference, H.W. Jones, andB.D. Fehl, eds. US Army Corps of Engineers Engineering andConstruction Directorate, San Antonio, TX. 28-30 August1995, pp 1195-1204[8] E.F. ONeil, and W.M. Dowd, Reactive Powder Concrete:A New Material for the Construction Industry, in: Proceedings,Third National Concrete and Masonry Engineering Conference,

S.K. Ghosh, ed., National Concrete and Masonry EngineeringConference, San Francisco, CA. June 15-17 1995, pp 43-50[9] D.J. Frew, J.D. Cargile, and J.Q. Ehrgott, W E SGeodynamics and Projectile Penetration Res earch Fac il ities, in: Proceedings, Ad vances in Numerical simulation Te c hnique s

for Penetration and Pe rf o ration of Solids, E.P. Chen, and V. K .Luk, eds. American Society of Mechanical Engineers, NewOrleans, LA, ASME Winter Annual Meeting, 28 Nov.-3 De c .1993, pp 1-8[10] M.J. Forrestal, B.S. Altman, J.D. Cargile, and S.J.Hanchak, An Empirical Equation for Penetration Depth ofOgive-Nose Projectiles into Concrete Targets, International

Journal of Impact Engineering, vol. 15, (4) (1994), 395-405[11] J.D. Cargile, unpublished experimental results, US ArmyEngineer Waterways Experiment Station, Geomechanics andExplosion Effects Division, Structures Laboratory, 1998[12] M.J Forrestal, and D.Y. Tzou, A Spherical Cavity-Expansion Penetration Model for Concrete Ta r g e t s , International Journal of Solids and Structures, vol. 34, (31-32),(1997) 4127-4146[13] S.A. Akers, M.L. Green, and P.A. Reed, Laboratory

C h a racterization of Ve ry Hi g h - St rength Fi b e r - Re i n f o rc e dConcrete, Technical Report SL-98-10, US Army EngineerWaterways Experiment Station, Vicksburg, MS. 1998

ENDNOTE* In this discussion, density (or in some contexts denseness)means the relative amount of volume in the freshly mixedproduct occupied by solid particles and not the mass per unitvolume of the product.

Dr. J. Donald Cargile is a senior research civil engineer for the Impact and Explosion Effects Branch of the

Geotechnical and Structures Laboratory at the US Army Engineer Research and Development Center (ERDC).He has worked at ERDC for over 21 years. He currently conducts research studying the response of geomate-

rials to the high intensity loadings associated with projectile penetration and explosive blasts. The research

involves both experiments and numerical simulation. Dr. Cargile received B.S. and M.S. Degrees in Civil

Engineering from Mississippi State University and a Ph.D. in Civil Engineering from Purdue University.

Mr. Ed F. ONeil is currently a research civil engineer for the Concrete and Materials Branch of the

Geotechnical and Structures Laboratory at the US Army Engineer Research and Development Center. His areas

of expertise are in material and structural properties of high-performance concrete and corrosion of metals in

concrete. His recent work has been involved with high-performance concretes comprised of ternary and quar-

tenary mixtures of cementitious materials. Mr. ONeil received a B.S. Degree in Civil Engineering from

Northeastern University and M.S. Degree in Civil Engineering from Purdue University. He is currently pursuinga Ph.D. in Civil Engineering from Northwestern University.

Mr. Billy D. Neeley is a research civil engineer for the Concrete and Materials Branch of the Geotechnical and

Structures Laboratory at the US Army Engineer Research and Development Center. He has over 20 years of

experience in applied research on concrete and concrete materials. His areas of expertise include the devel-

opment and placement of high-performance and specialized concretes. Mr. Neeley received a B.S. Degree

in Agricultural Engineering from Mississippi State University and M.S. Degree in Civil Engineering from Purdue

University.



10/10

AMPTIAC Directory

G ove rnment Pe rs o n n e l

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, AMPTIACDavid Rose201 Mill StreetRome, NY 13440-6916(315) 339-7023, Fax: (315) 339-7107Email: [email protected]

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Alion Science and Te chnology Pe rs o n n e l

AMPTIAC Celebrates Its 6th BirthdayOn November 1st, AMPTIACs staff took a few minutes out of their busy day to mark the IACssixth birthday. The six years have flown by, but are replete with accomplishments. We are proudof our success serving the DOD materials and processes community and look forward to contin-ued service in the future.


very-high-strength concretes for use in blast- and penetration

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