bluuebunny/crossref_metadata_2025 huggingface dataset:
Cement Clinker Characterization by Scanning Electron Microscopy
Authors: Stutzman PE
Published: January 2010

The scanning electron microscope (SEM) is becoming increasingly recognized as an important instrument for the study of portland cement clinker, cement, and concrete. Images of clinker surface topography are used to study particle size and shape, as well as fracture surface features. Microstructural features such as phase distribution and abundance are obtained by imaging polished surfaces. X-ray microanalysis provides qualitative and quantitative elemental composition and images of element distribution. Computer-based image analysis systems are used to process microscope images to enhance details (such as the separation of individual phases) and image analysis for the measurement of features (such as phase abundance). The linking of the SEM with X-ray microanalysis and image analysis under computer control will provide automated, quantitative, and consistent analysis of portland cement clinker.
An Analysis of Factors Affecting Particle-Size Distribution of Hydraulic Cements
Authors: Malghan SG , Lum L-SH
Published: January 2010

Particle-size distribution of hydraulic cements plays an indispensable role in controlling the product quality and maintaining reliable performance in end applications. Selection of particle-size measurement methods is becoming increasingly complex due to the availability of a variety of instruments based on different measurement principles. This paper discusses the primary criteria to be met by a particle-size distribution analzer for applications in hydraulic cement characterization. Among the several methods available for measuring the particle-size distribution, a light diffraction technique was utilized to examine the effect of dispersion solvents on the resulting size distribution. Distilled water, distilled water containing a polyacrylate surfactant, isopropyl alcohol, and a commercially available organic surfactant were used as dispersion solvents. The resulting data are analyzed with respect to variations due to the dispersion solvents and factors responsible for the observed variations.
Effect of Extended Use of Set-Retarded Concrete in Hot Weather
Authors: Mittelacher M
Published: January 2010

Test results from four major Florida projects were reviewed for effects of set-retarder use on maintaining slump and strength of concrete held in the mixer for extended time periods in hot weather conditions. Admixtures included ASTM Specification for Chemical Admixtures for Concrete (C 494) Type D water-reducing and retarding and Type G high-range water-reducing and retarding admixtures. Four different cement-admixture combinations were used. Design strengths ranged from 27.6 to 69.0 MPa (4000 to 10 000 psi). The test samples representing the longest delivery times were found to have maintained the specified slump. Their strength levels generally remained at, or exceeded, the average strength of the respective concrete class.
Some Applications of AC Impedance Spectroscopy in Cement Research
Authors: Gu P , Xie P , Beaudoin JJ
Published: January 2010

AC impedance techniques have been recently applied to investigate the electrical properties of hydrating cement pastes. A review of recent applications of AC impedance spectroscopy (ACIS) in cementitious materials studies including some relevant applications to microstructural characterization, silica fume content estimation, W-C ratio determination and microcracking of cement paste are presented.
High-Strength Concrete Properties Derived from Compressive Strength Values
Authors: Khayat KH , Bickley JA , Hooton RD
Published: January 2010

The determinations of modulus of elasticity and flexural and splitting tensile strengths often involve complicated testing procedures compared to compressive strength testing. These properties can be estimated using existing relationships between them and compressive strength values. However, most of the existing correlations have been derived for mixtures with compressive strengths less than 80 MPa and may not be applicable to mixtures of greater strengths. This paper compares compressive strength, splitting tensile strength, flexural strength, and modulus of elasticity values to similar results predicted by national codes and alternatives suggested by various researchers. Commercially available and laboratory-prepared concrete mixtures with 28-d compressive strengths of 45 to 110 MPa were tested.
The Passivation of Reinforcing Steel Exposed to Synthetic Pore Solution and the Effect of Calcium-Nitrite Inhibitor
Authors: Tullmin M , Mammoliti L , Sohdi R , Hansson CM , Hope BB
Published: January 2010

Potentiodynamic polarization studies were conducted on rebar steel in a simulated cement paste pore solution containing sodium chloride, with and without additions of calcium-nitrite inhibitor. The rebar steel passivated spontaneously and displayed an extensive passive potential range in both cases. Surprisingly, however, passivity breakdown was observed to occur at a lower potential in the inhibited solution. XPS surface analysis indicated a similar composition of the passive films formed in the inhibited and uninhibited pore solutions. Only trace amounts of nitrogen were detected in the passive films. On the basis of the XPS results and the reported nitrite-inhibition mechanism, it would appear that the smaller passive potential range associated with the inhibitor additions is related to a decrease in pH recorded after the inhibitor addition.
Amendment of Appendix X2 in ASTM C 917 Evaluation of Cement Uniformity from a Single Source
Authors: Sykora V
Published: January 2010

Test Method for Evaluation of Cement Strength Uniformity from a Single Source (ASTM C 917) in the ASTM Annual Book of Standards, Volume 4.01, Cement, Lime, and Gypsum provides methods to evaluate the cement strength uniformity from a single source. Test data comparing 1976 through 1977 and 1991 show a general increase in strengths over that period of time. In 1976, 45% of the labs had annual average 7-day strengths less than 27.6 MPa (4000 psi), while in 1991 none of the plants had averages below that level. The data show the cement industry, overall, shipped a more consistent product in 1991 compared to 1976 through 1977. The percentage of plants with a standard deviation below 2.1 MPa (300 psi) at 7 days increased from 63 to 81% during that time period. A higher percentage of plants had the total coefficient of variation and corrected deviations below 6%. The testing error remained the same with the 1976 data and the 1991 data, but the testing error coefficient of variation improved.
Properties of a Non-Film Forming Latex in Ceramic Tile Mortar
Authors: Kuhlmann LA
Published: January 2010

Latexes currently used for modifying portland cement contribute many property improvements to mortar and concrete. Many different polymers are used to make these latexes, but all have one thing in common: they form a film at normal working temperatures. It is the formation of this film that is generally understood to be critical to the performance of these latexes in portland cement and responsible for certain of the property improvements in the hardened mortar and concrete.

Contrary to this accepted understanding, an experimental latex has been developed for use in portland cement that does not form a film at room temperature. Instead, the latex particles maintain their integrity as spheres after the portland cement mixture hardens and still provides property improvement in the hardened mixture. The lack of film-formation also eliminates the stickiness during finishing and the surface crusting from air-drying that are typical of the film-forming latexes used in portland cement.

Tests of this latex were conducted on mortar with ceramic tile and compared to mortars using standard film-forming latexes. Workability, compressive strength, and shear bond of the mortars were evaluated. In addition, flexural bond strength of tile-to-plywood and cement backerboard was measured using a new test procedure.
Acrylic Powder Modified Portland Cement
Authors: Ci X , Falconio RR
Published: January 2010

The key functions of polymer in modifying cement for both indoor and outdoor applications have been identified and demonstrated through years of practice since the early 1960s. The effectiveness of using pure acrylic polymer in cement modification can be credited to the unique acrylic chemistry in combination with special polymer designs and processes. Both acrylic powder and acrylic latex rely on the acrylic backbone to provide excellent performance and durability, especially for exterior applications. Acrylic redispersible powder recently developed preserves acrylic latex performance in mechanical strength, adhesion, and water resistance as demonstrated by various tests under wet- and dry-exposure conditions. In addition, use of acrylic powder as a “one-package” alternative to latex facilitates on-site handling, environmental protection, and reduces packaging and transportation costs.

This paper presents the results of performance comparsion between acrylic redispersible powder and acrylic latex in cement modification. The polymer-modified mortar properties were evaluated and compared in both a typical concrete repair mortar and a ceramic tile formulation. The exterior durability of acrylic powder modified repair mortar was demonstrated through exterior exposure studies. The modification efficiency of acrylic powder was also studied at different polymer levels in a patching formulation that compared favorably to other commercial powders at lower polymer level usage.
Tensile and Compressive Strength of Silica Fume-Cement Pastes and Mortars
Authors: Toutanji HA , El-Korchi T
Published: January 2010

The effect of silica fume on the compressive and uniaxial direct tensile strength of portland cement paste and mortar is reported. Sixteen and 25% of the cement used in the paste and in the mortar, measured by mass, was replaced by silica fume. Four different W/C ratio mixtures were tested: 0.22, 0.25, 0.28, and 0.31. The super-plasticizer content was adjusted for each mixture to provide a sufficient amount for efficient dispersion of the cement and silica fume particles, but also to make sure that there would be no excess of this additive that might lead to effects such as bleeding.

Results show that the partial replacement of cement by silica fume increases the compressive strength of mortar but has no effect on the compressive strength of paste. Results also show that the partial replacement of portland cement by silica fume decreases the tensile strength of both paste and mortar. The reduction in the strength of paste was greater than the reduction in the strength of mortar. Results were verified by statistical analysis using hypothesis testing at a 95% confidence level. The uniaxial tensile strength results were obtained using the cementitious composites axial tensile technique (CCATT).

The relation between the tensile strength and compressive strength of materials with and without silica fume was obtained. The ratios of tensile to compressive strength of paste and of mortar were decreased with increasing silica fume content.
Mechanical Properties of Normal to High-Strength Steel Fiber-Reinforced Concrete
Authors: Khaloo AR , Kim N
Published: January 2010

A total of 84 specimens were tested to study the effect of concrete strength on the mechanical properties of concrete reinforced with randomly distributed steel fibers. The concrete strengths investigated include 25 MPa for normal-strength (NSC), 50 MPa for medium-strength (MSC), and 69 MPa representing high-strength concrete (HSC). Fiber content ranges from 0 to 1.5% by volume of the concrete matrix. The influence of concrete strength on the compressive strength, splitting tensile strength, and modulus of rupture of steel fiber-reinforced concrete (FRC) is presented. Based on the limited number of specimens tested, it was concluded that HSC provides considerable improvement in compressive strength for fiber content of up to 1% compared to that of NSC and MSC. Also, modulus of rupture of NSFRC considerably improves due to fiber compared to those of MSFRC and HSFRC. Splitting tensile strength results do not indicate a clear dependency to concrete compressive strength.
Factors Influencing Flow and Strength of Standard Mortars and Reappraisal of ASTM Test Methods for Fly Ash
Authors: Helmuth R
Published: January 2010

Modified Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use as a Mineral Admixture in Portland-Cement Concrete (ASTM C 311) Pozzolanic (Strength) Activity Index tests with five fly ashes and two portland cements were done to compare results with those of standard tests. When sand contents (at constant water and cement contents) were varied, strengths of 38°C cured mortars decreased (−30 to −50 kPa/g of sand added in mixes containing 1370 to 1570 grams of sand) for different cement/fly ash blends. When water contents (at constant sand contents) were varied, strengths varied (−125 to +190 kPa/mL), strengths tending to increase because of paste volume increases with water content. Flow of mortars in both kinds of tests increase nearly linearly with paste volume fractions; the slopes are related by a factor of 0.60 ± 0.04. Accelerated curing at 38°C for tests at 28 days usually yields higher relative strengths than after curing at 23°C for 91 days. Multiple linear regression equations using both kinds of test data are solved at specified flow and strength values to determine proportions and mortar volume yields. This more general performance test ranks fly ashes (or cementitious mixtures) by mortar volume yield at equal flow and strength, and is suggested as a candidate to replace the present Strength Activity Index test.
The Strength and Microstructure of High-Strength Paste Containing Silica Fume
Authors: Li Y , Langan BW , Ward MA
Published: January 2010

This paper describes the effect of silica fume on the strength and microstructure of high-strength paste. The particular tests carried out included: compressive strength, pore structure (mercury porosimetry), calcium hydroxide content, evaporable and non-evaporable water contents, and X-ray diffraction.

Water-cementitious ratios of 0.33, 0.30, 0.27, and 0.24 were tested at the ages of 14, 28, and 90 days. Silica fume contents were 5 and 10% of the total cementitious content by weight.

Results have shown that at a W/C ratio of 0.24, the strength of the paste decreased at all three test ages as the silica fume content increased. The positive influence of silica fume on the strength of paste decreased as hydration increased. The addition of silica fume did not reduce the total porosity but did reduce the maximum continuous radius significantly. X-ray diffraction results indicated that 10% silica fume virtually eliminated the calcium hydroxide content. The amount of non-evaporable water was less than would be expected by the reduction in the cement cogent.
Effect of Mixing Temperature on Slump Loss and Setting Time of Concrete Containing High-Range Water Reducers
Authors: Whiting D
Published: January 2010

Concretes containing high-range water reducers (HRWR) based on naphthalene (NHRWR) and melamine (MHRWR) condensation products were batched, mixed, and tested at temperatures of 7, 16, 23, and 32°C (45, 60, 73, and 90°F). The amount of HRWR necessary to obtain a fixed slump and water-cement ratio was found to increase with a decrease in temperature below 23°C (73°F) and to remain fairly constant from 23 to 32°C (73 to 90°F). Slump loss showed a significant increase with an increase in temperature across the entire range studied. Mixtures containing melamine-based HRWR exhibited somewhat higher rates of slump loss than did those containing naphthalene-based HRWR when a cement containing a moderately high tricalcium aluminate (C3A) content was used. No consistent differences in slump loss were found between the two admixtures when a cement with a somewhat lower C3A content was tested. At the dosages used in this study, HRWR exhibited significant, though not excessive, retardation of set. It was found that certain combinations of HRWR and lignosulfonate or hydroxycarboxylic acid type retarders can have a moderating effect on slump loss at elevated temperatures.
Air Content of Hardened Concrete from Comparison Electron Microscope Photographs
Authors: Mullen WG , Waggoner CK
Published: January 2010

The purpose of the research reported in this paper is to provide a rapid means for determining the entrained air content of hardened concrete by using scanning electron microscope photographs of fractured faces of samples from hardened concrete. The method that has been developed and verified at a reasonable level of confidence consists of an array of low magnification scanning electron microscope photographs of fractured faces of concretes of known air contents. The air contents range from 0 to 20% in increments of approximately 1%. At a magnification of ×80, air-entrained bubbles interrupted by the fracture face are visible as portions of hollow spheres. To determine the air content of a concrete a random series of photographs is made of fractured faces, and these are compared as a group to the array of known air content photographs until a best match is made. With untrained personnel, 1 σ precision, where σ is the standard deviation, of less than 1.5% has been obtained in selecting the correct air content for a concrete with an unknown air content.
Use of CCRL Reference Sample Results for Precision Statements
Authors:   ASTM Subcommittee C01.94 on Statistical Methods
Published: January 2010

The need for precision statements for most cement test methods and many concrete test methods can be satisfied by data already in existence in the Cement and Concrete Reference Laboratory Reference Sample Program. A simple technique for extracting the pertinent data is presented.
Roughness of Aggregates of Different Types by the Modified Fourier Method and Scanning Electron Microscopy
Authors: Czarnecka ET , Gillott JE
Published: January 2010

Three types of aggregates obtained by partial crushing of pebbles of different lithology and erosional history were investigated quantitatively with the modified Fourier technique. All the crushed particles were rougher, that is, more elongated and textured than the natural pebbles from which they were obtained. Surface texture increases more rapidly than the elongation. However, roughness, shape, and surface texture of the aggregates depend on the lithology of the raw material. There was also a difference in trend between changes of roughness within natural and crushed particles of different types when the size of the pebbles investigated decreased. Provided the number of profiles is representative, the modified Fourier method yields precise numerical values. These data could lead to improved control of the roughness, shape, and texture characteristics that have an important effect on the properties of aggregates in concrete. Studies with the scanning electron microscope showed conchoidal fractures on the surfaces of quartzite particles and finer textural features on limestone surfaces. These detailed features add to the surficial macrotexture of profiles investigated by the Fourier method.
Pigments for Integrally Colored Concrete
Authors:   Task Group of ASTM Subcommittee Section C09.03.08.05 on Methods of Testing and Specifications for Admixtures
Published: January 2010

A Task Group of ASTM Subcommittee Section C09.03.08.05 has developed laboratory tests for lightfastness, alkali resistance, water wettability, and curing stability of pigments to be used to integrally color concrete. A general purpose carbon black, which was hydrophobic, did not pass the water wettability test, but a hydrophilic concrete-grade carbon black readily mixed with water. Many otherwise attractive pigments, such as chrome yellow and iron blue, did not pass the alkali resistance test. Ultramarine blue is resistant to most alkalies, but calcium hydroxide gradually decomposes it, especially at elevated temperatures; therefore, ultramarine blue did not pass the curing stability test. None of the organic pigments tested passed the lightfastness test. Of the pigments tested, only iron oxide (natural and synthetic), chromium oxide, cobalt blue, and carbon black (concrete grade) passed all four tests.
Rapid Determination of the Predominant Form of Calcium Sulfate Found in Portland Cement and Its Effect on Premature Stiffening
Authors: Buchanan CE
Published: January 2010

The object of this research program was to enable us to predict very rapidly the performance of portland cement in the field in relationship to abnormal setting characteristics. A cement water leach is prepared, and the filtrates are analyzed for calcium and sulfate. A sodium (DI) ethylenediaminetetraacetate acid (EDTA) titration is used for the calcium and a turbidimetric method is used for the sulfate. Based on the results obtained with this chemical procedure, quality control methods that fairly accurately predict whether a cement contains an excessive amount of either anhydrite or plaster of paris have been prepared.
Investigation of ASTM Paste and Mortar Bleeding Tests
Authors: Kemp BG
Published: January 2010

This report outlines the results of testing to see if 1-1-1 trichloroethane can be substituted for carbon tetrachloride as the displacement medium in the ASTM standardized cement bleeding tests. This was necessary because highly toxic carbon tetrachloride is now banned from laboratory use in the United States.

Results show that the bleeding rates and bleeding capacities of various cement pastes and mortars are not significantly affected by the use of 1-1-1 trichloroethane. This report concludes that 1-1-1 trichloroethane may be substituted for carbon tetrachloride.

It is recommended that the design of the collecting ring in the bleeding apparatus be modified to prevent unwanted water bubbles from rising inside the collecting buret.
State of Solutes in Contact with Hydrating Tricalcium Silicate Pastes
Authors: Punzet-Karpisek M
Published: January 2010

There have been numerous excellent studies concerned with the mechanism of the early hydration reactions of tricalcium silicate. The determination of reaction kinetics through the use of conduction calorimetry, quantitative X-ray diffraction analysis, studies of the stoichiometry of hydration, and, now, the growth of calcium hydroxide crystals in water have been done. Data concerning the liquid-phase composition in contact with hydrating tricalcium silicate also have been reported.

The present paper will only give some references concerned with electrolyte solutions and experimental procedure.
Use of the Maleic Acid Method for the Determination of Cement Content of Concrete
Authors: Marusin SL
Published: January 2010

The determination of cement content of hardened concrete using the maleic acid (MMA) extraction method was evaluated using laboratory-prepared samples. The effect of variations in the strength of the maleic acid solution and sample digestion time were evaluated. The method was found to be very accurate. The difference between the actual and determined cement contents of the laboratory-prepared concretes ranged from 0.0 to 0.3 bags per yd3 with an average of 0.2 bags per yd3. A test procedure for using the method to determine the cement content in concrete cores is proposed. The method is recommended as an adjunct to petrographic examination, since significant errors may occur if the cement paste is extensively carbonated, if such admixtures or aggregates as fly ash or slag are present, or if the aggregates contain carbonate minerals.
Abrasion-Erosion Resistance of Fiber-Reinforced Concrete
Authors: Liu TC , McDonald JE
Published: January 2010

Fiber-reinforced concrete (FRC) has been used for repair of abrasion-erosion damaged areas such as stilling basins, conduits, sluiceways, and discharge laterals in hydraulic structures. However, the resistance of such concrete subjected to abrasive action of waterborne particles has not previously been evaluated.

A recent laboratory study on the abrasion-erosion resistance of FRC is presented in this paper. Thirteen concrete mixtures of three watercement ratios ranging from 0.40 to 0.72, each containing one of four different types of steel fibers, were tested. As is true of concrete without steel fibers, the abrasion-erosion resistance of FRC increased with a decrease in water-cement ratio and consequent increase in compressive strength. The lengths of the fibers had very little effect on the abrasionerosion resistance, and the FRC containing collated and hooked fibers had better abrasion-erosion resistance than the comparable concrete containing straight fibers.

A comparison of the performance of FRC and concrete not containing fibers clearly showed that FRC was less resistant to abrasionerosion than concrete of the same aggregate type and water-cement ratio without fibers. The abrasion-erosion losses of the FRC were consistently higher than that of the concrete not containing fibers over wide ranges of water-cement ratio and, hence, compressive strength.

Based on the results of laboratory tests and field performance experience, fiber-reinforced concrete is not recommended for use in new construction or repair of hydraulic structures in which abrasion-erosion is of major concern.
The Effect of Fly Ash on Concrete Alkali-Aggregate Reaction
Authors: Dunstan ER
Published: January 2010

Concrete aggregates may contain reactive constituents that will react with alkalies in cement causing disruptive expansions. Concrete deterioration caused by alkali-aggregate reaction can be prevented by using nonreactive aggregate or using cement with sufficiently low alkali content. However, energy conservation and pollution controls can be expected to indirectly increase the alkali content of some cements. On the other hand, the availability of nonreactive aggregate is continually reduced. Other preventive techniques, such as the use of pozzolan admixtures, can be used. But pozzolans vary in their effectiveness in reducing alkali-aggregate reactions. This paper discusses the use of fly ash pozzolan, a finely divided material collected from the exhaust flues of coal-burning power plants, to reduce alkali-aggregate reaction. The effectiveness of fly ash to reduce this reaction appears to depend, in part, on the chemical composition of the fly ash and also on the percent weight replacement of cement by fly ash.
On the Correlation of Consistency and Strength of Concrete to the Attrition Rate of Fine Aggregate
Authors: Parka N , Hansen TC
Published: January 2010

On the basis of experimental studies correlations were found between attrition rate of fine aggregates on one hand and consistency of fresh concrete and compressive strength of hardened concretes on the other. For fine aggregates complying with standard requirements, differences of up to 15 MPa (2100 psi) in compressive strength were observed between concretes made with high and low quality fine aggregates when other factors are essentially identical. For identical concrete mix proportions slump values between 190 and 0 mm (7.6 and 0 in.) were observed.
On the Correlation of Strength and Elasticity of Concrete to Los Angeles Abrasion Loss and Crushing Value of Indonesian River Gravels
Authors: Parka N , Hansen TC
Published: January 2010

On the basis of experimental results, correlations were established between, on the one hand, aggregate crushing value and the percentage of natural Indonesian river gravels lost as per the Los Angeles abrasion test and the compressive strength and the modulus of elasticity of hardened concretes on the other. For gravels complying with standard requirements, differences of up to 11.8 MPa (1678 psi) in compressive strength and up to 10.9 GPa (1.55 × 106 psi) in modulus of elasticity were observed between concretes made with high and low quality gravels.
A Strain Control System for Relaxation Studies of Concrete
Authors: Pirtz D , Thomas K
Published: January 2010

This paper describes a system of automatic strain control devised to maintain constant strain in concrete specimens during stress relaxation tests. The system also makes provision for continuous monitoring of strain and stress as the testing proceeds. Evaluation of the system performance from the results of relaxation tests conducted using the system showed that the strain control achieved during these tests was remarkably effective. The maximum variation from initial strain recorded was 0.5 × 10−6 microstrain (0.5 × 10−6 in./in.)
Definition and Measurement of Flexural Toughness Parameters for Fiber Reinforced Concrete
Authors: Johnston CD
Published: January 2010

Current and past approaches to assessing and defining the flexural toughness of fiber reinforced concrete are reviewed, and the difficulties associated with them are discussed. Refinements needed to ensure correct analysis and interpretation of load-deflection relationships in evaluation of flexural toughness are identified. A new system of defining toughness is proposed. It comprises a series of indices based on material behavior up to specified multiples of the first-crack deflection. This system is shown to be superior to the one currently advocated by The American Concrete Institute Committee 544 based on material behavior up to a deflection of 1.9 mm (0.075 in.). It is recommended as the basis for a standard test method to evaluate toughness, and appropriate provisions for inclusion in the standard are identified.
A Critical Look at ASTM C 618 and C 311
Authors: Butler WB
Published: January 2010

ASTM Specification for Fly Ash and Raw or Calcined Natural Pozzolan for Use as a Mineral Admixture in Portland Cement Concrete (C 618) is probably the most demanding specification for fly ash in the English-speaking world, with comprehensive provisions for both chemical and physical tests. However, the time delays involved and the cost of testing are often out of proportion to the benefits derived. ASTM Standard Methods of Sampling and Testing Fly Ash or Natural Pozzolans for Use as a Mineral Admixture in Portland Cement Concrete (C 311) does a creditable job of defining test methods to meet the needs of C 618, but neither document makes any attempt to grade testing frequencies for individual tests in a practical manner. With the new ASTM Committee C09.03.10 beginning the task of revising the documents, this seems a good time for a critical look at the status quo.
Development of High-Strength Concrete Incorporating a Large Percentage of Fly Ash and Superplasticizers
Authors: Mukherjee PK , Loughborough MT , Malhotra VM
Published: January 2010

In this paper results are reported of an investigation performed to develop high-strength concrete incorporating superplasticizers and a large percentage of fly ash as a replacement for normal portland cement. The concrete mix developed had a water to (cement + fly ash) ratio of 0.28, cement and fly ash contents of 390 and 230 kg/m3, respectively, and a large dosage of a superplasticizer. The 28-day compressive strength of 152- by 305-mm cylinders ranged from 51.0 to 53.8 MPa, and the 28-day flexural strength was approximately 8 MPa. The drying shrinkage and creep values were comparable to the corresponding values of the reference mix. It was concluded that the concrete developed was satisfactory in both workability and early age strength and should find uses in precast concrete operations for the production of high-strength structural units.
Durability Performance of Polymer-Modified Mortars
Authors: Ohama Y
Published: January 2010

Polymer-modified mortars have recently been widely used in construction work throughout the world because of their high strength, excellent adhesion, waterproofness, and chemical resistance. The durability performance of such mortars has not been extensively studied until now. Polymer-modified mortars using various polymer dispersions were prepared with different polymer-cement ratios and tested for weatherability, freezing-thawing resistance, heat resistance, and chemical resistance. The test results demonstrate that most polymer-modified mortars have better durability performance than conventional cement mortar.
Thermally Destructive Particles in Sound Dolostone Aggregate from an Ontario Quarry
Authors: Soles JA
Published: January 2010

A normally sound dolostone aggregate was found to be unstable in concrete during sustained heating at 150°C. Petrographic and other related investigations of the rock have indicated that the primary cause of deterioration of particles is the oxidation of iron sulfide. In this aggregate, fine pyrite is intergranular with dolomite, calcite, and clastic material, particularly in shaly sections. Analyses of disintegrated particles revealed that the granular powders consisted of unaltered carbonate and clastic grains, relict pyrite, and sub-micron material containing hygroscopic, iron-rich sulfate. It was concluded that the pyrite had oxidized to iron sulfate hydrate under these particular conditions; the resulting volume change disintegrated the permeable, often weakly bonded particles, and stresses arising from aggregate expansion ruptured the concrete. Tests revealed also that the aggregate was relatively stable at 75 and 300°C and in dry oxygen, which suggests that water vapor in a particular pressure-temperature range is critical for the reaction. Water released from the aggregate by sustained heating is in part responsible.
Ideal and Quasi-Ideal Grading of Coarse and Fine Aggregates for Mass Concrete
Authors: Ehrenburg DO
Published: January 2010

In an earlier publication the author presented a set of tables for proportioning continuously and gap-graded concrete of 38-mm (1.5-in.) maximum size, on the basis of Weymouth's theory of particle interference. In this paper, Weymouth's theory has been restated in algebraic form, thus making applications to mix proportioning less difficult. Moreover, tables for optimum grading of 76-mm (3-in.) maximum size coarse aggregate as well as tables for optimum grading of fine aggregate are included.
Development and Interaction of a Concrete Additive for Improved Performance and Durability
Authors: Syal SK , Kataria SS
Published: January 2010

Two percent of the additive lignin superplasticizer (SLC) that is developed by mixing equal amounts of alkali carbonate and black liquor sulfate/sulfite lye (that is, lignosulfonate-based material) from paper and pulp works in India can eliminate the use of gypsum and produce a cement with improved strength, lower water requirements (about 30% less) for the same consistency, and increase durability. When used as a simple additive to normal portland cement (clinker and gypsum system), it increased strength and durability to aggressive reagents and decreased the water requirement for the same consistency. Porosity, microstructural, and morphological studies suggest that the lower porosity and increased strengths observed in the presence of the additive are caused by the formation of a Type III calcium silicate hydrate gel in the early stages of hydration, instead of a Type I or a Type II calcium silicate hydrate gel that is generally observed in the normal systems. The atomistic mechanism explains that the increased durability in concretes is caused by a denser, more uniform cement matrix and a stronger matrix-aggregate bond.
Method of Lightweight Sand Production by Fluidized Bed Calcination
Authors: Akhundov AA
Published: January 2010

A method is described for producing lightweight sand by fluidized bed calcination. The procedure offers some advantages over other methods, including increased mechanization and higher quality products. Use of lightweight sand in concrete panels reduces cement consumption, vibration time, and concrete bulk density.
Mechanical Properties, Durability, and Drying Shrinkage of Portland Cement Concrete Incorporating Silica Fume
Authors: Carette GG , Malhotra VM
Published: January 2010

Portland cement is a highly energy intensive material, therefore, considerable effort is being made to find substitutes for partially replacing cement in concrete. Silica fume, a byproduct in the manufacture of ferrosilicon and silicon metal is one possible substitute. Results are given of a preliminary investigation to determine the strength, freezing and thawing characteristics, and drying shrinkage of concrete incorporating various percentages of silica fume.

Eighteen 0.06-m3 air-entrained concrete mixes were made incorporating 0 to 30% silica fume as a partial replacement for cement. Some mixes were proportioned to have constant slump with water to cementitious materials ratio (W/C + S) ranging from 0.64 to 0.84 whereas others were proportioned to have a constant W/C + S of 0.40; the latter incorporated a superplasticizer. Cylinder and prism specimens were cast for determining the mechanical properties and durability of concrete.

Test data indicate that silica fume when used in concrete as a partial replacement for cement performs as a highly efficient pozzolanic material. Notwithstanding the extreme fineness of silica fume (20 000 m2/kg) and, hence, its high water demand, the compressive strength of constant slump concrete incorporating up to 30% silica fume is comparable with or higher than the strength of control concrete.

Superplasticized concrete mixes having a W/C + S maintained at 0.40 indicate some increase in compressive strength at all ages regardless of the percentage of silica fume.

Concrete prisms incorporating 0 to 15% silica fume (W/C + S = 0.40) perform satisfactorily when subjected to 300 cycles of freezing and thawing; however, prisms incorporating 20 to 30% silica fume and large dosages of superplasticizer show excessive expansion and relatively low dynamic moduli after 300 cycles. The drying shrinkage of concrete incorporating silica fume is generally comparable with that of control concrete regardless of the W/C + S.
The Incorporation of Low Levels of By-Products in Portland Cement and the Effects on Cement Quality
Authors: Daugherty KE , Funnell JE
Published: January 2010

This paper has attempted to show that the cement industry in the United States can accomplish significant reductions in its total energy consumption by intergrinding industrial by-products such as slags, fly ashes, kiln dusts, and possibly other industrial by-products with cement clinker. Further, as seen in many countries this reduction can be accomplished without sacrifice in cement product quality. This study undertook an analysis and evaluation of the utilization of a variety of slags, fly ashes, and kiln dusts in combination with Type I cements from a number of cement plants. Additionally, a significant portion of the project effort was directed on fostering more widespread usage of industrial by-products in blended cement manufacture in the United States and promoting within the industry, ASTM, and other cognizant agencies the adoption of performance specifications applicable to the energy-saving blended cements.

This study was a step in the direction of energy savings that can be attained through blended cement production and use. There are potentially many additional means of further reducing the energy requirements of cement manufacture, as was discussed in the excellent report on the use of energy within the cement industry.
The Potential Use of Catalysts in the Cement Industry
Authors: Safa AI , Daugherty KE , Mallow WA , Dziuk JJ , Funnell JE
Published: January 2010

The calcination of calcium carbonate in a cement or a lime kiln requires approximately two to four times the theoretical quantity of energy predicted from thermodynamic analysis depending upon the type of cement kiln used. The potential for using catalysts to reduce the total energy requirements was explored. It is, of course, impossible to reduce the theoretical energy requirement for the calcination process. Two possible ways considered to reduce this total requirement were (1) to either increase the rate of calcination at a specific temperature or (2) to decrease the temperature of calcination. Several classes of catalysts show promise of doubling the calcination rate (or decreasing the energy requirement by ½).
Waste Fuels Program at the Mississauga Plant of St. Lawrence Cement, Inc.
Authors: MacDonald LP
Published: January 2010

Used automotive oil containing approximately 0.5% lead, 0.1% bromine, 0.1% zinc, and 0.1% phosphorus was burned in a suspension preheater kiln. Lead, zinc, and phosphorus emissions were not found to be increased. A material balance showed these elements to be retained in the process solids. No effect on cement quality was detected.

Waste chlorohydrocarbons including polychlorinated biphenyls were burned in a wet-process kiln. These compounds were destroyed in the cement kiln flame. The chlorine liberated reacted with process materials reducing the alkali content of the clinker.

Coke containing high contents of sulfur and significant levels of vanadium and nickel was burned in the wet-process kiln. Nickel and vanadium were almost entirely retained in the clinker. Sulfur retention depended strongly on burning conditions within the kiln.
The Use of Unconventional Fuels in Cement Manufacture
Authors: Capon BM , Layne PB , Watson D
Published: January 2010

For more than half a century combustible materials have been used to a limited extent to substitute partially for coal, oil, or gas as the main fuel for cement manufacture, and the continuing increase in price of the conventional fuels is increasing the incentive to do this wherever it is technically practicable and economic. This paper discusses and quantifies the theoretical aspects of this topic, particularly the influence of the properties, continuity of supply, delivered cost and processing cost of possible alternative fuels, the tolerance of the cement-making process according to the type of process and raw materials and cement product quality requirements. Guidelines are developed and are illustrated by reference to the results of research and development and pilot plant work and practical experiences of a number of full-scale applications including a large and novel plant and system for consuming domestic refuse (municipal garbage) in a cement works.
The Grace Factor: A New Tool for Cement Industry Process Control Engineers
Authors: Welch PW
Published: January 2010

A method for mill control and supervision is described that is based on measurement of the mill horsepower consumption and the bulk density of the material being ground. Control by horsepower is shown to be possible and to be a more fundamentally based scheme than other commonly used systems. A monitoring and control system is discussed that uses the relationships described to provide a visual indication of mill loading conditions that can be used effectively by nontechnically trained personnel for manual mill control or as an automatic signal for direct control interlock with programmable controllers.
Study of Alkali-Silica Reactivity Tests to Improve Correlation and Predictability for Aggregates
Authors: Heck WJ
Published: January 2010

Evaluation of ASTM Tests for Potential Reactivity of Chemical Aggregates (Chemical Method) (C 289), Potential Alkali Reactivity Cement-Aggregate Combination (Mortar-Bar Method) (C 227), and Petrographic Examination of Aggregates for Concrete (C 295) for predicting alkali-silica reactivity potential of aggregates was undertaken using a natural siliceous sand and a manufactured limestone sand to which 2, 5, 10, and 20% by weight of reactive materials (chert and opaline sandstone) were added. Three aggregate gradings were tried in the mortar-bar test. None of the test methods by themselves are adequate to predict alkalisilica reactivity potential; furthermore, the chemical test did not correlate well with the limit of mortar-bar expansion at an age of six months as indicative of reactive aggregate. There is a linear trend between the amount of reactive material and the amount of soluble silica by weight added to the sands and reduction of alkalinity determined by the chemical test. A similar linear relationship is shown between the amount of soluble silica and the amount of reactive material in the aggregate as determined by petrographic examination. The pessimum proportion of the reactive material was found to be around 10% by weight. Coarser graded aggregate tended to produce greater expansion, but this was not definitely established. Mortar-bar expansion tends to be highly variable with increase of amount of reactive material over 2%. The test data indicates that the limit of mortar-bar expansion of 0.1% at six months does not adequately define potentially reactive material. It is suggested that the limit should be lowered to 0.075% at six months. Because of the effect of grading and the variability of expansion, consideration should be given to replacing the mortar-bar test with a concrete-prism test. Limestone aggregate appears to have an inhibiting effect on alkali-silica reactivity, therefore, adding limestone to reactive aggregates may be a practical way to make them usable in concrete. Further testing should be conducted to establish the minimum amount of limestone required to effectively inhibit reactivity.
Some Questions Concerning ASTM Standards and Methods of Testing Fly Ash for Use with Portland Cement
Authors: Helmuth R
Published: January 2010

Although the potential for substantial energy conservation by the use of fly ash in blended cements is well recognized, present test methods and standard specifications do not appear to be adequate to insure predictable performance. A review of the literature led to an analysis of the scientific bases for existing tests for water requirement for pozzolanic activity. Questions are raised concerning the use of fixed proportions in both tests. It is suggested that proportions be adjusted in the mortar flow test to take into account the 45-μm (No. 325) sieve residue of the fly ash. It is also suggested that variable proportions of fly ash and cement be used in the pozzolanic activity tests to facilitate optimization of concrete properties.
Variation of Laboratory Concrete Flexural Strength Tests
Authors: Greer WC
Published: January 2010

An analysis of 145 laboratory flexural-strength concrete mixes prepared for projects at the expansion of the Atlanta International Airport is presented. Typical values for within-test (within-batch) and between-test (between-batch) standard deviations are presented and compared with data published by others. Flexural strength as a function of age in the laboratory is discussed, and typical values are given for Type I cement mixes.
Alkali Reactivity of Strained Quartz as a Constituent of Concrete Aggregate
Authors: Buck AD
Published: January 2010

Some strained quartz may cause a deleterious alkali-silica reaction if present as a constituent of concrete aggregate in sufficient amounts. The criterion for reactive strained quartz is suggested to be more than 20% strained quartz with an average undulatory extinction angle greater than 15°. Length changes of mortar bars containing such strained quartz will be 0.025 and 0.040% or more at six and twelve months, respectively, when stored at a temperature of 60°C (140°F). Revisions to applicable ASTM standards may be appropriate.
Efficient Large Panel Roofing
Authors: Matselinsky RN , Rogatin YA , Spannut LS
Published: January 2010

Large panel building roofs using prestressed short cylindrical panel-shells with dimensions of 3 by 12, 3 by 18, and 3 by 24 m developed in the U.S.S.R. are presented in this paper, and their technical and economic advantages in comparison with other roofs are shown.