bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Strength Concrete: An Annotated Bibliography 1930–1979
Authors: Carrasquillo RL , Nilson AH , Slate FO
Published: January 2010

The purpose of this bibliography is to present a guide to the existing literature on high-strength concrete. This bibliography covers most of the relevant writings of this subject in the English language and some writings in other languages. High-strength concretes are here defined as concretes with strengths considerably higher than usually obtained by a given production process. There is general agreement on the need for a unified effort for the development of knowledge of this new material so that it may be used with confidence in design and construction.
The Action and Application of Two New ASTM Specifications for Shrinkage-Compensating Cement in Concrete: ASTM C 845 and C 878
Authors: Gulyas RJ , Garrett MF
Published: January 2010

The past theory of the action of shrinkage-compensating cements is discussed and recent findings that refute the internal compressive stress concept are presented in favor of the American Concrete Institute (ACI) Committee 223 net positive elastic strain behavior (spring action theory) for the proper functioning of concrete with shrinkage-compensating expansive cement.

A method of using less than the minimum ACI-223 committee recommendation of 0.15% steel is presented based on two past research studies.

Examples of typical installations are shown along with some interesting concepts that deal with curvature control (curling/warping) as a result of reversed differential shrinkage/expansion strains. A case for using less than the minimum ACI-318 recommendation of 0.188% steel is also presented for this type of concrete in structural reinforced concrete. The proper type of expansion/isolation joints are presented that exclude current ASTM materials.

This paper provides the design engineer with a summary of the current research and thinking for design concepts for the use of this material that is fundamentally different than conventional concrete. It also describes the working relationship of ASTM Specification for Expansive Hydraulic Cement (C 845) and ASTM Test for Restrained Expansion of Shrinkage-Compensating Concrete (C 878), respectively, covering shrinkage-compensating expansive cement and its concrete prism for measuring expansion strains.
An Experimental Technique for Obtaining Complete Stress-Strain Curves for High Strength Concrete
Authors: Shah SP , Gokoz U , Ansari F
Published: January 2010

For a rational design of concrete structures, it is necessary to know both the ascending and the descending parts of the stress-strain curve of concrete subjected to uniaxial compression. It is difficult to determine the descending part experimentally because of the interaction between the testing system and the specimen, especially for concrete of high compressive strength. The influence of the testing machine depends on the stiffness of the machine, the frequency response of the system, the length and diameter of the specimen, the strength of concrete, the rate of loading, and the inherent brittleness of the material. For a closed-loop testing machine, the specimen-machine interaction also depends on the parameter chosen to control the loading. It is shown that the descending part of the curve can be obtained by controlling the circumferential strain even when the axial strain control produces an unstable failure. A method of testing specimens at a controlled rate of circumferential strain increase is described. Stress-strain curves of concrete subjected to uniaxial compression using both the axial and the lateral strain as a control were compared for compressive strengths ranging between 70 to 90 MPa (10 000 to 13 000 psi).
Proportioning of Coarse Aggregate for Conventionally and Gap-Graded Concrete
Authors: Ehrenburg DO
Published: January 2010

This paper presents a set of tables for proportioning 38-mm (1.5-in.) maximum size conventionally or gap-graded concrete. The tables were compiled on the basis of Weymouth's concept of particle interference, considerations of minimum surface area, and certain other considerations. It will be noted that the recommended gradations of the coarse aggregate often lie somewhere between conventional and gap-graded patterns. Laboratory tests have established the validity of the proposed method. The procedure is laboratory oriented in that the matrix requirement is established on the basis of trial mixes. The meshing of test results with data obtained from the proposed tables is illustrated by a practical example.
Evaluation for Durability and Strength Development of a Ground Granulated Blast Furnace Slag
Authors: Hogan FJ , Meusel JW
Published: January 2010

This paper covers the evaluation of a ground granulated blast furnace slag as a partial replacement for portland cement in mortars and concrete. The ground slag was evaluated for strength-producing properties as well as durability performance when used to replace 40 to 65% portland cement. This study shows that the ground slag when used to replace 40 to 65% portland cement did significantly improve strengths, sulfate resistance, and alkali aggregate reactivity.
Influence of Pozzolanic, Slag, and Chemical Admixtures on Pore Size Distribution and Permeability of Hardened Cement Pastes
Authors: Manmohan D , Mehta PK
Published: January 2010

Durability of concrete is greatly influenced by the permeability of the cement paste which in turn is governed by the pore size distribution. Some mineral and chemical admixtures are known to enhance the durability of portland cement concrete. The objective of this work was to investigate how the pore size distribution and permeability of portland cement pastes are modified by the addition of pozzolanic admixtures, blast furnace slag, and chloride salts. The effectiveness of pozzolans in reducing the volume of large pores and permeability was found to depend on the reactivity of the pozzolan used. Large additions of granulated blast furnace slag increased the total pore volume, however the pore size distribution was shifted toward finer pores and therefore the permeability of the paste was reduced. Among the chloride admixtures, namely calcium, magnesium, and sodium chloride, magnesium chloride was most effective in reducing both the volume of large pores and permeability of the cement pastes.
Flexural Fatigue of Polymer Concrete
Authors: Woelfl GA , McNerney M , Chang CJ
Published: January 2010

This paper describes modulus of rupture and flexural fatigue testing performed on beam specimens made of Silikal® polymer concrete and course aggregate. Test results indicate that modulus of rupture of polymer concrete increases with increasing rate of loading similar to portland cement concrete. Fatigue test results show good correlation with a mathematical expression relating probability of survival with stress level and number of cycles to failure. This equation was developed and used by other investigators for portland cement concrete. Test results indicate that frequency of loading influences the fatigue life of polymer concrete, but a short rest period within each loading cycle probably does not. Further fatigue study is recommended in the paper.
Production of Artificial Porous Aggregates from Fuel-Containing Industrial Wastes in the USSR
Authors: Ivanenko GP , Vasilkov SG
Published: January 2010

Data on the use in the USSR of fuel-containing industrial wastes in the production of artificial porous aggregates for lightweight concrete are presented. The main peculiarities of the production technology of artificial porous aggregates from thermal power plant ashes, by-products of mining, and concentration of coal are presented. Formation processes of the porous structure's of aggregates during production by agglomeration method is discussed. Data on properties of porous aggregates and lightweight concrete are presented.
Variability and Control of Class C Fly Ash
Authors: McKerall WC , Ledbetter WB
Published: January 2010

Five Class C fly ashes produced in Texas were analyzed for their potential usefulness as a construction material in highways. In order to determine the variability a new test method was devised and termed the calcium oxide heat evolution test, whereby the total calcium oxide content of the Class C fly ashes can be quickly and reliably determined in the field, as a quality control test. By using this test plus the traditional physical and chemical characterizations, the variability of typical fly ashes produced in Texas was ascertained. They were shown to generally conform to the requirements of ASTM for Class C fly ash. In addition to the analysis the potential usefulness of this type of fly ash is discussed, and the test procedures for calcium oxide content are described.
Chloride Penetration and the Deterioration of Concrete Bridge Decks
Authors: Cady PD , Weyers RE
Published: January 2010

The rapid deterioration of the nation's bridges is a widely recognized problem. A major contributor to this problem is bridge deck deterioration caused by chloride-induced corrosion of reinforcement. Chlorides are derived primarily from the application of roadway deicing salts. This paper synthesizes empirical data from previous studies with the diffusion theory in developing a predictive model for chloride infusion of bridge decks. The model includes the effects of subsidence cracking over the reinforcement. Primary input data consist only of average reinforcement cover, which is easily obtainable with existing instrumentation. The model is intended to serve as a useful, rational means of providing information for life-cycle costing in bridge deck rehabilitation planning studies.
A Method for Analyzing Void Distribution in Air-Entrained Concrete
Authors: Philleo RE
Published: January 2010

A method is derived that makes possible the determination of the fraction of hardened cement paste within any stipulated distance of the nearest air void as a means of determining the extent to which the paste is protected from the damaging effects of freezing. The required input consists of the total air content and the number of air voids per unit volume. Both can be determined from a Rosiwal linear traverse performed by microscope on a polished section of concrete. Determining the void density requires a count of chord intercepts in two or three small size groups.
Principles Underlying Production of High-Performance Concrete
Authors: Mehta PK , Aïtcin P-CC
Published: January 2010

Durability rather than high strength appears to be the principal characteristic for high-performance concrete mixtures being developed for use in hostile environments such as seafloor tunnels, offshore and coastal marine structures, and confinement for solid and liquid wastes containing hazardous materials. Strength, dimensional stability, impermeability, and high workability are usually the principal characteristics required of high-performance concrete.

In this paper an overview of the composition of concrete and its effect on the properties desired for high performance is given. This overview can be used as a basis for selection of component materials and mix proportioning. A new step-by-step procedure for mix proportioning is described. The calculated mix proportions from this procedure appear to be consistent with the state-of-the-art laboratory and field practice. Also, a brief review is given of concrete production and construction practices essential for making a high-performance end product.
The Influence of Size and Hardness of Sand Particles and Their Proportions on the Friction Characteristics of Cement Mortars: A Laboratory Study
Authors: Kolias S
Published: January 2010

Laboratory friction tests on cement mortar specimens, prepared with various fractions of limestone and emery sand, were carried out using the accelerated polishing machine and the British pendulum tester. Two types of investigations were performed. The first consisted of mixes with constant grading of sand, either limestone or emery, in which one fraction was replaced by the same fraction of the other type of sand. The second consisted of mixes of limestone sand in which a certain amount of emery sand, each one of four different fractions, was added each time. The exact amount of emery sand added was calculated for each fraction so that in each series of tests the total surface area of emery sand was constant, regardless of the fraction used.

It was found that the finer fractions are more effective in influencing the skid resistance value (SRV) of mortars. The max increase in SRV (29.7%) is achieved when the 0.297/0.149 fraction of limestone sand is replaced by the same fraction of emery sand; therefore, an SRV value of approximately 90% of the SRV of mortar, containing entirely emery sand, is obtained. The second investigation confirmed that the total surface area of hard particles determines the friction characteristics of the mortars. It seems, however, that an optimum total surface of hard particles exists, and further increase of which does not cause additional increase of the SRV.
The Use of the Flow Length Concept to Assess the Efficiency of Air Entrainment with Regards to Frost Durability: Part I—Description of the Test Method
Authors: Pleau R , Pigeon M
Published: January 2010

This paper describes a numerical method to determine the flow length and other characteristics of the air-void system in hardened concrete. Physically, the flow length represents the distance that freezable water must travel through the cement paste to reach the perimeter of the nearest air void. It is expected to be a better indicator of the frost durability of concrete than the commonly used Recommended Practice for the Microscopial Determination of Air Void Content and Parameters of the Air Void System in Hardened Concrete (ASTM C 457) spacing factor. The flow length is obtained from the microscopical examination of polished concrete sections. It can be determined by recording the size-distribution of the circles intercepted by the plane on a given surface area or by recording the size-distribution of the chords intercepted along a given line of traverse. A numerical example is given to illustrate the advantages of the proposed method. The flow length is very similar to the Philleo factor, but it provides a more accurate estimation of the real distribution of air voids through the cement paste.
Introduction to Symposium on Concrete Fracture Mechanics Standards
Authors: Struble LJ
Published: January 2010

Several of the following papers in this issue were presented at an ASTM Committee C-9 Symposium on Fracture Mechanics Standards in December 1996. I had the privilege of chairing this symposium, with the help of an organizing committee (consisting of Nicolas Carino and Lawrence Roberts).
Do We Need a Standard Concrete Fracture Mechanics Test?
Authors: Struble LJ , Lange D
Published: January 2010

Fracture mechanics has allowed scientists and engineers to understand brittle fracture and to determine the conditions that cause a crack to grow in an brittle manner and lead to failure of the structure. In this paper we consider the information that fracture mechanics provides, especially that which is not obtained from a simple test of strength. Fracture mechanics provides a measure of toughness, the extent to which a material can undergo deformation without fracturing. For a linear elastic material, the measurement and interpretation of fracture toughness is fairly straightforward. Concrete is not such a material; it is rather described as quasi-brittle, and only recently has research led to the development of fracture mechanics tests suitable for such quasi-brittle materials. We show in this paper that fracture toughness provides considerable information about concrete over and above what we can learn from strength. We also show how the practicing engineer can benefit from the use of fracture criteria in design. However, fracture specifications will not be developed until there is a standard test method. Researchers have now developed tests that are suitable as standards. Therefore, we conclude that a need exists for a standard test and that it is time to begin its consideration.
Setting Times of Fly Ash and Slag-Cement Concretes as Affected by Curing Temperature
Authors: Eren O , Brooks JJ , Celik T
Published: January 2010

Using Test Method for Time of Setting of Concrete Mixtures Paste by Penetration Resistance (ASTM C 403), Proctor penetration resistance was determined under isothermal curing temperatures ranging from 6 to 80°C for concretes containing up to 50% of fly ash or ground-granulated blast-furnace slag. The results show that as the temperature increases, the initial and final setting times decrease for all types of concrete, with fly-ash concrete having the longest setting times. At high temperatures, slag concrete has shorter setting times than Type I cement concrete. Relationships are presented for setting time as a function of penetration resistance, temperature, and cement replacement level.
Efficiency of Natural Greek Pozzolan in Chloride-Induced Corrosion of Steel Reinforcement
Authors: Kouloumbi N , Batis G , Pantazopoulou P
Published: January 2010

This experimental work estimates the corrosion behavior in a sodium-chloride environment of steel reinforcements in mortar specimens with 0, 15, and 30% Greek natural pozzolan, cured either for 1, 7, or 28 days. The corrosion resistance was evaluated by measuring the corrosion potential development of steel rebars, their gravimetric mass loss, their anodic potentio-dynamic behavior, and the total- and free-chloride content of the mortars. Additionally, their mineralogical composition was determined by X-ray diffraction (XRD) analysis. The increase of curing time, as well as the addition of the Greek natural pozzolan, for both percentages tested, improved the corrosion behavior. The combination of the pozzolan addition with longer curing time reduces the steel rebars mass loss up to a level of about 40% after five months of exposure.
Why the Accelerated Mortar Bar Method ASTM C 1260 is Reliable for Evaluating the Effectiveness of Supplementary Cementing Materials in Suppressing Expansion Due to Alkali-Silica Reactivity
Authors: Bérubé M-A , Duchesne J , Chouinard D
Published: January 2010

The Accelerated Mortar Bar Method (AMBM) ASTM C 1260 (or CSA A23.2-25A) is used with success for evaluating the effectiveness of supplementary cementing materials (SCMs) in suppressing expansion due to alkali-silica reactivity in concrete (ASR). This study attempts to answer the question of why this method gives good results with SCMs. The most beneficial effects of SCMs against ASR is thought to be alkali decrease in the pore solution while the bars are immersed in 1N NaOH at 80°C. Mortar bars made with different SCMs were tested in normal conditions as well as in pure water and in air at 100% RH. The expansion results were compared with the chemistry of the mortar pore solution expressed under high pressure. The results confirmed that in the presence of an SCM, the alkali decrease in the pore solution remains the most critical mechanism involved in the AMBM. The results also confirmed that alkali equilibrium between the pore solution and the NaOH immersion solution is not achieved in the presence of an SCM at the end of the testing period of 14 days.
Determination of Silica Fume in Unhydrated, Blended, Dry-Packaged Mixture, and Hydrated Mortar
Authors: Coleman SE , Hwu S , Vogt WL
Published: January 2010

A test method is proposed as a quality control methodology to determine the relative amount of dry silica fume present in a prepackaged blend of dry, unhydrated, cementitious material. The method assumes availability of representative samples of each of the raw material ingredients prior to packaging, including portland cement, silica fume, fly ash, silica sand, and a representative sample of the mixed product. Known percentages of silica fume by weight of portland cement were added separately to a basic blended mixture and analyzed by combined heat treatment and X-ray diffraction (XRD) method. From a calibration curve developed from standard laboratory mixtures, an estimate of the amount of silica fume in a prepackged cement was determined with a reasonable degree of accuracy.

Additionally, a neat portland cement and portland cement + fly ash + sand mixtures containing different proportions of silica fume by weight of cement were hydrated at W-C = 0.30 and analyzed at selected periods for up to 180 days to determine residual silica fume. The diminution of calcium hydroxide (formed by the hydrating portland cement) in the cement-fly ash mixture and in the combined silica fume and fly ash cement mixtures were monitored during this period using thermogravimetric analysis and scanning electron microscopy.
Rapid Determination of the Fly Ash Content of Construction Materials
Authors: Schlorholtz SM , Dubberke W
Published: January 2010

Since 1989 this laboratory has had good success using X-ray fluorescence (XRF) methods to determine the amount of fly ash that is present in portland cement-fly ash mixtures. The method has been used on mixtures of dry cementitious constituents prior to batching, and also on portland cement-fly ash mortars and concretes. The method is based on the determination of the concentration of barium (Ba) and strontium (Sr) present in the construction materials. Since these two elements are greatly enriched in Iowa fly ashes they act as “finger prints” for the presence of fly ash, and if the proper criteria are satisfied, they also allow for the quantification of the amount of fly ash in a given mixture. The method works best when it can be calibrated with materials taken directly from a given jobsite. The method is very quick since samples can normally be analyzed in less than 10 min. The sample preparation process does not involve extraction techniques that use hazardous solvents. With a modern, computer-controlled X-ray fluorescence spectrometer the method can also be extended to determine many other elements present in the sample, such as sulfur (S) and chlorine (Cl), which may be of importance to investigations concerning the chemical attack of portland cement-based materials.
A New Consecutive Dissolution Method for the Analysis of Slag Cements
Authors: Goguel R
Published: January 2010

The best means of selective dissolution of ordinary portland cement (OPC) from ground granulated blast-furnace slag (BFS) cements has been, until now, a sodium-based alkaline aqueous solution of ethylenediamine-tetraacetate with chelating properties supplemented by the presence of 6% triethanolamine (TEA).

Selectivity of the solvent is substantially improved by replacing sodium with tetramethylammonium (TMA). This large cation has a selective decelerating effect on the release of aluminum from aluminosilicate glasses. Thus, its introduction slows down dissolution of BFS and slightly accelerates the dissolution of OPC. This improvement removes the need for careful buffering at pH 11.6. A higher pH (for example, 12.5) is used, which avoids the formation of siliceous precipitates.

Further, it was found that the use of lithium as cation makes the EDTA-TEA solution a good solvent of BFS that allows separation from aggregates based on aluminosilicate rocks. Consecutive application of the two versions of the same chelating system thus allows good separation and quantitative dissolution of OPC and BFS from the unhydrated slag-cement.

Determination of the degree of hydration of BFS could be derived from measurements of Ca and Si in the leach rather than the measurement of weight losses during leaching. This technique reduces errors from the formation of solvent resistant Mg-Al-hydroxide phases (for example, hydrotalcite) and extends the range of application.
Determination of Silica-Fume Content in Hardened Concrete by AC Impedance Spectroscopy
Authors: Gu P , Xie P , Beaudoin JJ
Published: January 2010

A nondestructive method based on AC impedance spectroscopy was applied to studies of the electrical behavior of hydrated portland cement concrete containing silica fume. Silica fume content significantly influenced the impedance behavior of hydrated portland cement concrete. Correlations between the high frequency arc (HFA) diameter and the silica-fume content in concrete were obtained. Empirical relationships for concrete binders at early and more advanced hydration can be expressed as 1DHFA=Koβsf+Cfor early hydration times and 2DHFA=C′(Ko′)βsffor advanced hydration times where DHFA is the high frequency arc diameter, βsf is the silica-fume content, Ko, K′o, C, and C′ are constants related to hydration times and W-C ratio, and so forth.
Trinity Square: Commentary on Concrete Test Data
Authors: Bickley JA
Published: January 2010

The paper describes the use of in-place testing instead of standard cylinder testing. Removal of forms and shores, and determination of concrete strength compliance with specifications were all controlled by pullout tests.

The criteria were written into the contract specification, and the relevant sections are quoted as a model for future use. Based on correlation data with standard cylinder tests, the building officials allowed the elimination of the usual mandatory standard cylinder tests. Standard tests were made however to provide comparison with the in-place tests. The paper shows that the in-place test provided an adequate measure of the quality and strength of the concrete.
Soundness Testing and Durability of Coarse Aggregates in Concrete
Authors: Cady PD
Published: January 2010

Throughout its long history, sulfate soundness testing of aggregates has been frequently cited for poor reliability as a predictor of concrete durability. However, its use remains widespread, even to the point of constituting an acceptance test criterion for aggregates. Sodium sulfate soundness tests of coarse aggregates are compared in this paper with freezing and thawing tests of air-entrained concretes containing the aggregates. In one case, sodium sulfate soundness displayed a relationship to durability (freezing and thawing) test results, in a statistical sense, but the level of predictability was poor. In another test series, the level of predictability fell within the range of pure chance.

The attractiveness of sulfate soundness testing is apparently derived from its simplicity and directness. However, it is shown in this paper that a combination of two aggregate property tests, specific gravity and absorption, provide a better predictor of freezing and thawing durability. Furthermore, these two tests are routinely run on aggregates and are even simpler than the sulfate soundness test.
The Maturity Method: Theory and Application
Authors: Carino NJ
Published: January 2010

The maturity method may be used to predict the in-place strength of hardening concrete based on its thermal history. A theoretical basis for the maturity method is presented. The general form of the time-temperature function is found to be the time integral of the rate constant. For the case of linear dependence between temperature and the rate constant, the time-temperature function becomes the traditional maturity function. The Arrhenius equation is shown to be an accurate representation of the temperature dependence of the rate constant, and the concept of equivalent age is explained for practical application of the Arrhenius equation. It is explained how the accuracy of strength prediction by the traditional maturity method can be improved by using the proper datum temperature. Results illustrate that the appropriate value of apparent activation energy or datum temperature for concrete may be obtained from strength-gain data of isothermally cured mortar specimens.
Influence of Petrography of Argillaceous Carbonates on Their Frost Resistance in Concrete
Authors: West TR , Shakoor A
Published: January 2010

Argillaceous carbonate rocks, when used as coarse aggregate, have been found to cause severe pitting and popouts in several Indiana highways within one winter after construction. These rocks were studied in detail petrographically to determine texture, structure, and mineral composition, and in particular the amount, type, and mode of distribution of argillaceous material.

Results of petrographic examination were compared with other test data including specific gravity, absorption-adsorption values, pore characteristics, and loss in freeze-thaw. This comparison suggests a close relationship between petrographic characteristics and freeze-thaw resistance of argillaceous carbonates. A comparison of petrographic information with field performance shows that those rocks that contain more than 20% silt and clay distributed uniformly throughout the rock mass result in pitting and popouts while those in which silt and clay are concentrated as streaks and laminations are not necessarily unsound. This is contrary to several previous investigations that concluded that laminated carbonates should be considered nondurable without specific concern for their total argillaceous content.
The Inhibition of Chloride-Induced Corrosion in Reinforced Concrete by Calcium Nitrite
Authors: Gaidis JM , Rosenberg AM
Published: January 2010

Reinforcing steel in portland cement concrete is subject to accelerated corrosion in the presence of chloride ions. A corrosion-inhibiting admixture based on calcium nitrite has been shown to confer protection (that is, to inhibit corrosion) if the chloride to nitrite weight ratio (Cl−/NO2−) does not exceed 1.5. Visual observations made on rebars in limewater solutions containing chloride and nitrite ions, current and potential measurements on concrete cylinders with embedded reinforcing bars (rebars), and potential measurements on simulated concrete bridge decks were in substantial agreement.
Factors Affecting the Reactivity of Fly Ash from Western Coals
Authors: Harris HA , Thompson JL , Murphy TE
Published: January 2010

This study of 16 fly ashes from various Colorado and Wyoming coals will show the relationship of coal and fly ash analyses to pozzolanic activity with portland cement. Samples have been followed from the coal source through the power plant combustion and collection system to show the effects upon fly ash quality for use as a mineral admixture in concrete. Each coal source is analyzed using ASTM Method for Proximate Analysis of Coal and Coke [D 3172-73(1984)] and classified by rank under ASTM Classification of Coals by Rank (D 388-84). The ash is analyzed and studied using ASTM Method for Sampling and Testing Fly Ash or Natural Pozzolans for Use as a Mineral Admixture in Portland Cement Concrete (C 311-85).

The problems associated with the present ASTM fly ash classification are shown in these samples by the conflicting data relative to their coal source and chemical analyses. Based upon the existing classifications under ASTM Specification for Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete (C 618-85), both Class C and Class F ashes are studied.
Effect of Chemical Admixtures on Portland Cement Hydration
Authors: Odler I , Abdul-Maula S
Published: January 2010

The effect of selected chemical admixtures on the progress of portland cement hydration, composition of the hydration products, and strength development was studied. Calcium chloride (CaCl2) accelerated the hydration of both tricalcium silicate (C3S) and tricalcium aluminate (C3A) and increased the calcium oxide/silicon dioxide (CaO/SiO2) ratio of the formed calcium-silicate-hydrate (CSH) phase. In the presence of zinc oxide (ZnO), Na-lignosulfonate, and a melamine resin, the hydration of both C3S and C3A was retarded, while in the presence of sucrose only that of C3S. The effect of all these additives was more pronounced if pure C3S rather than portland cement was employed. Regardless of the kind and amount of admixture added (except high amounts of CaCl2) and hydration time, the bound water content, amount of liberated calcium hydroxide, and compressive strength were linear functions of the amount of hydrated C3S.
History and Use of Blended Cements in Turkey
Authors: Öztekin E , Cimilli T
Published: January 2010

The number of cement plants in Turkey increased from 1 in 1911 to 39 in 1985 and the yearly cement clinker production capacity from 20 000 to 21 000 000 metric tons, respectively. Production of blended cements started in the late 1960s and in 1970 accounted for 20% of the total output. However, the share of the blended cements increased to 30% in 1975, to 75% in 1979, and to 92% in 1985. Of the four types of blended cements produced (namely, modified portland cement, trass cement, iron portland cement, slag cement), modified portland cement appears to be popular, accounting for 72% of the total cement production in 1984. This paper briefly looks at the historical background, describes the types of cements produced, collates the available data on pozzolanic materials and cements, and discusses the trends in the use of blended cements.
The Use of Fly Ash in Concrete: Classification by Composition
Authors: Thomas MDA , Shehata MH , Shashiprakash SG
Published: January 2010

Fly ash has been used as a pozzolanic admixture in concrete for more than 50 years. Earlier uses were largely confined to low-calcium ashes from hard bituminous or anthracite coals. However, increased demand for fly ash coupled with the declining availability of suitable low-calcium ashes has attracted a wider variety of fly ashes to the marketplace in recent years. Some of these ashes are characterized by very high calcium contents (for example, >25% CaO) and such materials affect the properties of concrete in a different manner than “traditional” fly ashes. The latest Canadian Standard covering fly ash for use in concrete divides fly ash into three categories strictly on the basis of its calcium content. This paper provides a rationale for this change in concept.
Use of the Accelerated Mortar Bar Test for Evaluating the Efficacy of Mineral Admixtures for Controlling Expansion due to Alkali-Silica Reaction
Authors: Thomas MDA , Innis FA
Published: January 2010

This paper presents data from laboratory studies to assess the suitability of the accelerated mortar bar test (CSA A23.2-25A and ASTM C 1260) as a method for evaluating the effect of mineral admixtures on expansion due to alkali-silica reaction (ASR). A wide range of materials such as fly ash, slag, silica fume and natural pozzolans have been tested at different replacement levels in combination with various reactive aggregates including siliceous limestone, greywacke, granite and sandstone. Results are presented for 70 different material combinations tested by both the accelerated test and the Canadian Standards Association concrete prism test (CSA A23.2-14A and ASTM C 1293).

For aggregates that were shown to be deleteriously reactive by both test methods there was a generally good agreement between the test results when the failure criteria used were expansion of mortar bars at 14 days > 0.10% and expansion of concrete prisms at 2 years > 0.040%. Only 5 out of 70 mixtures passed the mortar bar test and failed the concrete prism test and in two these 5 cases the extent of failure was insignificant (that is, 0.042% expansion at 2 years in both cases). It is concluded that combinations of pozzolans and reactive aggregates that pass the accelerated mortar bar test can be used in the field with a very low (and acceptable) risk of deleterious expansion due to ASR.

A large number of the mortar bars were subjected to pore solution expression and analysis after 14 days in 1 M NaOH at 80°C. There is a broad correlation between the pore solution alkalinity and expansion at the end of the test. This suggests that the mineral admixtures suppress expansion in this test by reducing both the alkalinity of the pore solution in the bar and the penetration (diffusion) of alkalis into the bar from the host solution.
Use of Ground Granulated Blast Furnace Slag for Reduction of Expansion Due to Delayed Ettringite Formation
Authors: Miller FMG , Conway T
Published: January 2010

Two cements, with a demonstrated tendency in mortars to suffer expansion related to delayed ettringite formation when cured at high temperatures ≥75°C, were tested after substitution of 5, 17.5, and 30 % with a ASTM C 989 Grade 100 ground granulated blast furnace slag. The two cements are here characterized as a “highly expansive” and a “moderately expansive” portland cement, according to the tendency of each to expand when stored in limewater after curing at elevated temperatures >75°C. Expansion was reduced or delayed, but not eliminated, with 5 % slag substitution, but completely absent when 17.5 % slag substitution was used. Compressive strengths were measured on cubes cured at ambient temperatures and at 90°C. Test results indicated that no strength penalty was experienced in mortars with high slag substitution, cured at 90°C; in fact, the compressive strengths were superior for the 30 % slag mixes, at all ages tested (from 1–28 days of hydration). The conclusion is tentatively reached that the use of blast furnace slag to reduce proclivity to DEF is effective, and does not involve any sacrifice in mortar compressive strength, at least to 28 days of hydration.
Strength and Density of Laboratory-Prepared RCC Specimens: Effect of Compaction Procedure
Authors: Shihata SA
Published: January 2010

Appropriate compaction is essential in producing roller-compacted concrete (RCC). An experimental program was conducted to study the effect of compaction on the strength and den-sity of RCC specimens. Compaction was achieved by tamping the sample with a hammer similar to that of ASTM D 1557. The main variables were the magnitude of compaction energy, number of lay-ers per mold, and cement content. The compaction energy ranged from 300 to 2700 kN-m/m3. The test results show that the decrease of the unit weight by 7.7% decreases the compressive and splitting tensile strengths by 73 and 71%, respectively. Increasing the cement content compensates for the reduction in compaction energy. The average degree of compaction of the cores taken from the field RCC test slabs was 99% of the unit weight of field samples prepared with a 2700 kN-m/m3 compaction energy.
Kinetics and Microstructural Changes Associated with Mortar Expansion
Authors: Pade C , Struble LJ
Published: January 2010

Mortar expansion data have been fitted to various kinetic models. The expansion tests utilized several aggregates (Pyrex glass, Vycor glass, calcined flint, Spratt's aggregate, and Beltane opal) and cements with various alkali contents. A very good fit was observed using a model developed to describe autocatalytic chemical reactions, and a fairly good fit was observed using a model for topochemical reactions. Microstructural studies showed that the reaction of Pyrex and Vycor involved highly localized attack of the glass, while reaction of calcined flint was less localized and appeared to be associated with preexisting internal fractures. For all three aggregates, the mortar expansion appeared to be associated with expansion of individual aggregate particles.
Quantitative Petrographic Technique for Concrete Damage Due to ASR: Experimental and Application
Authors: Rivard P , Fournier B , Ballivy G
Published: January 2010

An automatic petrographic test procedure for quantifying damage in concrete affected by alkali-silica reaction (ASR) is presented in this paper. A computer image analysis program was designed to quantify the degree of microcracking and the amount of silica gel resulting from ASR. The procedure involves the petrographic examination at a magnification of ×20 of polished concrete sections impregnated with fluorescent epoxy resin for cracking and uranyl acetate coated sections for the determination of their silica gel content. Also, the data were compared to the results obtained from a semi-quantitative petrographic method, i.e., the Damage Rating Index commonly used in Canada for evaluating the condition of concrete affected by ASR.

The petrographic examination was first carried out on laboratory sections cut and polished from concrete prisms incorporating two different aggregate types, the Spratt limestone and the Potsdam sandstone. Both methods were also applied to specimens prepared from a core collected from a large dam affected by ASR. Good correlation was obtained between analytical parameters derived from the image analysis method and the expansion levels of the laboratory test prisms; however, no explicit relation was found to date between the amount of gel as measured in this study and the expansion level.

This study shows that the quantitative petrographic method using the image analysis and the Damage Rating Index Method can be used to estimate the condition and current expansion of concrete specimens cored from concrete structures affected by ASR.
Influence of Silica Fume on the Stresses Generated by Alkali-Silica Reaction
Authors: Ferraris C , Garboczi E , Stutzman P , Winpigler J , Clifton J
Published: January 2010

Present test methods for determining the suitability of a given combination of cement and aggregates with respect to the potential for alkali-silica reaction (ASR) are based on the measurement of the expansion of the concrete/mortar under prescribed conditions. The scope of this study was to determine the influence of the addition of silica fume as a cement replacement on the stresses generated by the specimen, a parameter that could be useful for the engineer. Cylindrical specimens were placed in a frame equipped with a load cell that fixed the axial strain at approximately zero and measured the axial stress generated over time. A replacement of cement by silica fume at a dosage of 15% by mass for two different w/c ratios led to a significant decrease of the measured stress. SEM observations helped to provide a tentative explanation for the stress and expansion reduction mechanisms with the addition of silica fume.
Case Study in Performance Testing of Hydraulic Cement
Authors: Struble LJ , Taylor PC , Conway JT
Published: January 2010

A testing program has been initiated to measure and compare the performance in concrete of two hydraulic cements. Both meet the prescriptive specification for portland cement; one cement is a mixture of 98% portland cement and 2% slag, and the other is a similar portland cement with no slag. The program compares their performance in a broad range of standard mortar and concrete tests. Mixes include both chemical admixtures (an air-entraining agent and a water reducer) and mineral admixtures (ground, granulated blast furnace slag, and Class F and Class C fly ashes). The preliminary results show only minor differences in performance between the two cements. An important conclusion of this presentation is that a standard protocol is needed for measuring performance of cement in concrete. The testing program we used is quite broad and includes several tests that are not part of the performance specification for hydraulic cement. Many of the standard tests for hydraulic cement provide quality tests for use in cement production, but do not assure that the cement will perform properly in concrete. A standard protocol would include a range of tests that assure performance of cement in concrete, would include other concrete materials (aggregates, chemical admixtures, and mineral admixtures), and would reduce the number of tests required to assure performance of a new cementitious material.
Analysis of Variables Influencing the Average-Residual Strength of Fiber-Reinforced Concrete
Authors: Hays CD , Mohammed NK , Zollo RF
Published: January 2010

The ASTM C 1399, Test Method for Obtaining Average Residual-Strength of Fiber-Reinforced Concrete, became a standard of ASTM International in December 1999. The test method was developed to provide a practical method, both functionally and economically, for evaluating the performance of fiberreinforced concrete (FRC) of any mixture design. The method is a flexure test and the result, the average residual strength (ARS), is a useful parameter in design and quality control testing. The current standard requires a third-point flexural loading-configuration that complies with ASTM C 78, Standard Test Method for Flexural Strength of Concrete (Using Simple Beam With Third-Point Loading), and net-deflection data analysis. Five factors, consisting of loading configuration, deflection measurement, support apparatus, testing machinery and fiber material type are used as test variables in this research in a testing program suited to the application of a statistical analysis of variance procedure, ANOVA, for their affect on ARS. The results of the test program show that no significant effect is found on the value of ARS computed according to ASTM C 1399 for the modified ASTM C 78, MC78, test apparatus when using either gross or net deflection, or when using third-point or centerpoint loading. There is a significant effect on the value of ARS computed according to ASTM C 1399 for the ASTM C 78 test apparatus when comparing the same test variables.
Evaluation of Precision of a Nuclear Gauge for Measurement of Water and Cement Content of Fresh Concrete
Authors: Nagi M , Whiting D
Published: January 2010

An experimental program was conducted to develop a precision statement for a commercially available nuclear field gauge developed to measure both water and cement contents of fresh concrete. Five gauges were tested at a single site. Three separate batches of concrete having different mixture proportions were tested; each gauge was run by a single operator. Data analysis was carried out following ASTM C 802-94 and the precision statements were developed in accordance with ASTM C 670-91a. Gauge count ratio was used rather than actual cement and water content to avoid the errors associated with gauge calibration. The “one-sigma limit” and the “difference two-sigma limits” were obtained. The precision estimates appear to reflect actual experience with the gauge and can be used to compare results obtained in the field.
Evaluation of Tests for Toughness/Abrasion Resistance and Durability/Soundness of Coarse Aggregates
Authors: Wu Y , Parker F , Kandhal PS
Published: January 2010

Many tests have been developed to empirically characterize aggregate without necessarily strong relationships with the performance of final products incorporating these aggregates. This seems to be particularly true for “toughness and abrasion resistance” and “durability and soundness.” Toughness/abrasion resistance and durability/soundness of aggregate are correlated, but represent resistance to degradation when subject to mechanical forces and weathering, respectively. A literature review identified five toughness/abrasion resistance and four durability/soundness test procedures. Sixteen aggregates with a wide range of properties were tested with eight of the identified test procedures. Results from the tests and test precisions were compared.
Early Shrinkage Development in a High Performance Concrete
Authors: Lepage S , Baalbaki M , Dallaire É , Aïtcin PC
Published: January 2010

As autogenous shrinkage in low water/binder concrete starts to develop almost as soon as portland cement hydrates it is very important to start shrinkage measurement just after the dormant period. One simple way to do it is to insert a gage and a thermocouple at the center of the concrete sample to monitor early shrinkage. Vibrating wire gages having a low rigidity modulus can be used to monitor at the same time length and temperature changes. It is then possible to evaluate separately the actual total deformation while concrete is hydrating at a temperature which is not constant, and autogenous shrinkage in isothermal conditions.

Early shrinkage measurements in a 0.30 water/binder ratio concrete beam (250 by 250 by 900 mm) are presented. It is shown that during the first 50 h due to the temperature increase of concrete the actual total shrinkage is much smaller than the autogenous shrinkage, occurring in isothermal conditions particularly during the first 24 h. Moreover a slight swelling of concrete has even been measured from 4 to 16 h.

Relative humidity inside the concrete sample was measured using a special probe placed close to the vibrating wire gages. This probe was inserted just after initial setting, 6 h after casting. The initial reading indicates a (RH) relative humidity of 97% and after 28-days the measured RH was still 93%.