bluuebunny/crossref_metadata_2025_split huggingface dataset:
Improved Utilization of Fly Ash in Concrete Through a Chloride-Free Accelerator
Authors: Popovics S 
Published: January 2010

Abstract
The strength accelerating effect of a chloride-free admixture is investigated with two types of commercially available portland cements, each with two different fly ashes. The accelerator is a water-soluble organic material belonging to the carboxylic acid group. The results show that considerable strength increases are produced by the use of this accelerator. For instance, specimens in which 25 and 30% of the portland cement was substituted by fly ash reached or approached the 28-day strength of the control specimens without fly ash but at the same water-cement ratio.
A New Statistical Method for Prediction of Concrete Strength from In-Place Tests
Authors: Stone WC , Reeve CP 
Published: January 2010

Abstract
A method is presented for determining the functional relationship (correlation curve) between an in-place parameter and the compressive strength of concrete, based on laboratory-conducted tests. The method accounts for the error in both X (in-place) and Y (compressive strength). A statistical procedure is developed for predicting the characteristic strength of concrete in the field, which accounts for the variability of the field-conducted in-place tests, the difference between the coefficients of variation associated with the in-place parameter and the compressive strength, and the error in the laboratory-derived correlation curve. It is concluded that a normal or lognormal distribution can be assumed for the compressive and in-place strength of concrete when fitting the correlation curve, but for prediction of the characteristic strength in the field the lognormal assumption is necessary unless the associated coefficient of variation is less than 15%.
Evaluation of the Potential for Expansion and Cracking of Concrete Caused by the Alkali-Carbonate Reaction
Authors: Rogers CA 
Published: January 2010

AbstractAlkali-carbonate reactive rock was inadvertently used in the Cornwall and Ottawa areas of Ontario between 1978 and 1982. The excessive expansion and cracking caused by this reaction resulted in the need to replace concrete within three years of construction. This reaction of dolomitic limestone with the alkalies from cement is well known in the Midland-Kingston areas of Ontario. It had not been expected in the Cornwall and Ottawa areas. In an effort to prevent further occurrences of this reaction, 17 quarries in the Gull River Formation were studied. Aggregate durability tests, chemical analysis, and concrete prism expansion tests were conducted on 26 bulk aggregate samples. Concrete prism expansion tests were conducted at alkali contents of 1.25 and 3.0% sodium oxide (Na2O) equivalent. Results showed that the current Canadian Standards Association specifications are inadequate for recognizing some alkali-carbonate reactive aggregates. This was due to the occurrence of delayed expansive aggregate. It is recommended that the concrete prism expansion test be conducted using cement with an alkali content of 1.25% Na2O. Those aggregates that exceed 0.025% expansion at one year should not be used in highway structures exposed to deicing salt. A rapid chemical screening test is proposed. The determination of the calcium oxide to magnesium oxide (CaO:MgO) ratio and alumina content or insoluble residue can be used to screen potentially alkali-carbonate expansive rocks from those that are nonexpansive.
Fracture of Concrete Subjected to Impact Loading
Authors: John R , Shah SP 
Published: January 2010

AbstractTo evaluate the response of concrete structures subjected to impact or impulsive loading, it is essential to know how cracks propagate under such dynamic loading conditions. Single-edge notched beams were subjected to varying rates of loading to establish the stress intensity factor K1 versus crack velocity V relationship for mortar and concrete. Impact tests were performed using a modified instrumented Charpy test system. During loading, the rate of crack growth was obtained using special brittle Krak gages.Results indicate the following: (1) For a given strain rate the extent of pre-peak crack growth is larger for concrete than for mortar, and the amount of pre-peak crack growth decreases with increase in strain-rate. (2) Decrease in pre-peak nonlinearity at higher strain rates is probably caused by the decrease in amount of slow (pre-peak) crack growth. Hence, the linear-elastic fracture mechanics (LEFM) approach at high rates may be valid. (3) To obtain realistic size independent value of stress intensity factor, slow crack growth should be included in the calculation for cement composites. (4) The relationship between log K1 and log V is nonlinear especially at the higher rates of loading, for both mortar and concrete.
Properties of High-Strength Concrete
Authors: Swamy RN 
Published: January 2010

Abstract
This paper presents data related to the development of high-strength concrete with special emphasis on the development of high early strength. Both these objectives were achieved by using an ultrafine portland cement with a specific surface of about 750 m2/kg or a high early strength portland cement with about 75% tricalcium silicate content. Experimental data are then reported on strength and elasticity properties, stress-strain behavior, heat of hydration, shrinkage, and creep of these concretes. The results show that using an ultrafine cement, concrete with adequate workability and one-day strengths of 60 to 80 N/mm2 and 35 to 40 N/mm2 can be obtained with granite aggregates and lightweight aggregates, respectively. With high early strength cement and lightweight aggregates, strengths of 10 to 25 N/mm2 in 12 h, and 25 to 45 N/mm2 in 1 day were achieved.
Concrete Deterioration Through Leaching with Soil-Purified Water
Authors: Hime WG , Erlin B , McOrmond RR 
Published: January 2010

Abstract
An unusual variety of concrete deterioration was encountered. The distress was due to concrete exposure, during a decade of service, to poorly drained calcium-absorptive acidic soil, and ground water having a negative Langlier saturation index. The calcium loss was due to a mechanism akin to ion-exchange or chromatographic phenomena. The deterioration resulted in the essential depletion of calcium of the portland cement paste, which left relatively pure silica gel. The attack was accelerated because the concrete was very porous in areas, a result of the manufacturing process used to make the concrete conduit.
Steps to prolong concrete service life in similar environments include use of dense and low-permeable concrete, limestone aggregate, and limestone fill. This type of aggressive environment can be identified in the field by use of kits that measure calcium-absorption characteristics of soils, and pH.
Water Soluble Polymers: The Relationship Between Structure, Dispersing Action, and Rate of Cement Hydration
Authors: Bradley G , Howarth IM 
Published: January 2010

Abstract
This paper attempts to describe some of the benefits that can be gained from adopting a “purpose building” approach to the synthesis of polymeric materials as dispersants for cement. Our work with copolymers of acrylic or methacrylic acids and their hydroxy alkyl esters has enabled us to investigate the importance and effects of variables such as molecular weight, comonomer ratios, and composition of the polymers on the deflocculation and hydration of cement. These investigations have enabled us to produce materials with significantly improved dispersant properties compared to currently available dispersants for cement and concrete. Our results also indicate that the inherent retardation characteristics of these polymers, on rate of cement hydration, can be overcome by addition of known accelerating additives.
New Test for Determining Fundamental Frequencies of Concrete
Authors: Gaidis JM , Rosenberg AM 
Published: January 2010

Abstract
The standard methods for determining fundamental frequencies of concrete specimens (ASTM Test Method for Fundamental Transverse, Longitudinal and Torsional Frequencies of Concrete Specimens [C 215]) can be markedly improved by using modern electronic equipment. In the new method, a small accelerometer pickup senses the vibrations of a concrete specimen after it is lightly struck, and a spectrum analyzer portrays the information in the frequency domain. The main advantages of the new method are speed, ability to test small specimens, and no noise; the chief disadvantage is higher equipment cost.
Comparative Study of the Microstructures of Normal and Very High-Strength Concretes
Authors: Sarkar SL , Aïtcin P-C 
Published: January 2010

Abstract
The microstructure of a normal concrete with water/cement ratio (W/C) = 0.56 (f′c at 28 days = 31.8 MPa or 4610 psi) was compared with two series of very high-strength concretes (up to 118 MPa or 17 120 psi), one made with Type III cement and the other with the same Type III cement plus 6 to 10% silica fume. These concretes were water cured for 91 days. Their microstructural examination was undertaken using mercury porosimetry and scanning electron microscopy-energy dispersive X-ray analysis (SEM-EDXA).
Similarities and differences are described in detail. Basically, both are composed of calcium silicate hydrates (C-S-H) and calcium hydroxide (C-H), but their proportions and morphology are quite different. The composition and types of C-S-H also vary. Significant differences in porosity and aggregate-cement bonding are present. Chloride ion permeability tests indicate the very high-strength concretes to be as impervious as polymer-impregnated types.
An Experiment to Investigate Chloride Intrusion on Construction Joints in Concrete
Authors: Denes T , Buck AD 
Published: January 2010

Abstract
A field experiment was conducted to investigate the extent of chloride intrusion along the construction joint between later-placed, cement-based grout and concrete in instrumented precast concrete breakwater elements (dolosse). Experimental blocks were cast, grouted, and submerged in seawater. Upon retrieval, the construction joint between the grout and the concrete was evaluated for chloride intrusion from seawater using X-ray diffraction (XRD) and energy dispersive X-ray analysis (EDX) of scanning electron microscope (SEM) samples. No detectable intrusion occurred, indicating that the planned instrumentation of dolosse in a field experiment should be secure from significant seawater intrusion.
Cost-Effective Control of Concrete Quality Using Small Specimens of Mortar Extracted from Concrete
Authors: Johnston CD , Smith GJ 
Published: January 2010

Abstract
Based on criticisms of the traditional approach to the control of concrete quality which often relies entirely on 28-day compressive strength assessment, a new approach is proposed which involves monitoring quality in various ways from the time of mixing. The alternatives examined are: recording batch weights to establish W-C ratio, monitoring consistency, analyzing freshly prepared mortar or concrete mixtures to determine water content and cement content, and assessing strength potential by means of autoclave or hot-water curing. On the basis of past case histories, it is concluded that assessment of strength potential must remain the primary assurance of concrete quality, and that the other alternatives can only complement rather than substitute for strength assessment.
The techniques proposed for mixture analysis and strength assessment involve testing specimens prepared from a sample of mortar extracted from the parent concrete, on the premise that just about anything that is detrimental to the quality of the concrete will manifest itself in the quality of the extracted mortar. Provided the relationship between mortar and concrete strength is established from trial mixtures or past plant records for the materials in question, it is shown that strength potential can be effectively and routinely assessed using autoclave or hot-water curing of 25 by 50 mm (1 by 2 in.) mortar cylinders, and that water content can likewise be determined from oven drying of small specimens of mortar. The problem of determining cement content with acceptable accuracy and precision is not completely solved either by the wet-sieving technique discussed herein or by any of the other available physical or chemical techniques.
The techniques proposed for strength assessment and mixture analysis offer considerable potential for cost savings in concrete quality control because of the small size of the facilities needed, their consequent portability, and their relatively low capital and operating costs compared with the equivalent costs of conventional concrete testing.
Significance of Interrupted Testing on the Freeze-Thaw Resistance of Fly Ash Concrete by ASTM C 666 (Method A)
Authors: Langan BW , Ward MA 
Published: January 2010

Abstract
This investigation studied the effect of interrupted testing combined with prolonged freezing on the freeze-thaw resistance of concretes containing fly ash as part of the cementitious fraction, using ASTM Test Method for Resistance of Concrete to Rapid Freezing and Thawing (C 666-84, Method A). Also studied was the effect of “marginal” air contents on the above test parameters. Test results indicate that for fly ash concretes with air contents in excess of 5%, interrupted and/or prolonged periods of freezing do not affect the freeze-thaw resistance of the concrete. Early age freezing (14 days) of fly ash concretes did not appear to be detrimental to the performance of the fly ash concretes tested.
Statistics of Shrinkage Test Data
Authors: Wittmann FH , Bažant ZP , Alou F , Kim J-K 
Published: January 2010

Abstract
A large series of concrete shrinkage tests which can be used for statistical purposes is reported. The series involves two groups of 36 identical cylindrical specimens, with a diameter of 83 mm for Group 1 and 160 mm for Group 2. Statistical analysis of shrinkage strains and strain rates is presented, and the goodness of fit by normal distribution, log-normal distribution, and gamma distribution is analyzed. Correlations between the values at various times are determined.
The study reveals only the intrinsic randomness of the shrinkage process (along with measurement errors) and omits the superimposed uncertainties due to randomness of environment and to prediction uncertainties in the influence of material composition, curing, and other factors. It is found that the coefficient of variation of shrinkage values first decreases with time and then levels off at 6 to 9%. The normal, log-normal, and gamma distributions all give acceptable fits of the observed distributions. There are small systematic deviations from normal distribution: the distributions are slightly skewed to the right and slightly platykurtic. The skewness is more pronounced for the distribution of shrinkage rates, and asymmetric distributions such as gamma give slightly better fits. The correlation of single specimen shrinkage deviations from the group mean at various times is characterized by correlation coefficients. Their value is found to decrease slowly as the length of the time interval increases. For shrinkage rates, this decrease is much faster. The standard deviation of the single specimen shrinkage from its smoothed shrinkage curve is much less than (about one third of) the standard deviation of the single specimen relative to the mean for all specimens. The standard deviation of all single-specimen smoothed shrinkage curves at one time is almost the same as (about 95% of) the standard deviation of the original unsmoothed data for that time.
The Rate of Absorption of Aggregates
Authors: Winslow DN 
Published: January 2010

Abstract
The rates at which aggregates approach their 24-h water absorption values have been measured for a variety of aggregates. The aggregates varied widely in both their total pore volume and median pore size. The rates of water uptake were found to vary greatly, with some aggregates taking in about 90% of their 24-h uptake within the first minute and others taking in only about 20%. Larger pore sizes and pore volumes seem to promote faster rates. It was found that aggregates with a rapid uptake would have given erroneous Iowa Pore Index test results. It was also found that there was no correlation between an aggregate's early rate of absorption and its freeze/thaw durability.
Experimental Studies of Elastic Wave Propagation in High-Strength Mortar
Authors: Monteiro PJM , King MS 
Published: January 2010

Abstract
A comprehensive test program on the behavior of high-strength mortar under different conditions has been performed by studying the propagation of ultrasonic waves (compressional and shear) through 2-in. (0.051 m) cubes. The increase of the ultrasonic wave velocities was monitored as a function of time. The attenuation of the ultrasonic waves under different conditions was analyzed. Special emphasis was given to the study of the effect of cracking on the ultrasonic velocities and attenuation of the mortar, including the development of anisotropic behavior once cracking had developed. The healing of the cracks over time was also analyzed, and it was shown that a substantial degree of healing can occur. The effects of changes in relative humidity and subzero temperatures on the seismic wave velocities were studied in detail.
Concrete Incorporating High Volumes of ASTM Class F Fly Ash
Authors: Giaccio GM , Malhotra VM 
Published: January 2010

Abstract
This paper gives results of an investigation undertaken to develop additional data on mechanical properties, and freezing and thawing resistance of high-volume Class F fly ash concrete made with ASTM Types I and III cements.
A series of eight concrete mixtures involving twelve batches, each 0.06 m3 in volume, were made at a water-to-cementitious materials ratio of 0.32 ± 0.01. The fly ash-to-(fly ash + cement) ratio was 0.56. The cement content of the mixtures was 154 kg/m3. All mixtures were air-entrained and superplasticized. The mixtures incorporated Type I and Type III cements, various combinations of as-received fly ash, beneficiated fly ash, and condensed silica fume.
From the test results, it is concluded that high-volume fly ash concrete has excellent mechanical properties and satisfactory resistance to repeated cycles of freezing and thawing. The use of ASTM Type III cement appears to be essential when high strengths at early ages are required. For concretes made with ASTM Type I cement, the use of beneficiated fly ash, and beneficiated fly ash and condensed silica fume, does little to enhance the properties of concrete compared with “as received” fly ash. For concrete made with ASTM Type III cement, the benefits of using beneficiated Class F fly ash and condensed silica fume are not clear.
Testing and Evaluation of a Novel Melamine-Based Superplasticizer in Concrete
Authors: Lahalih SM , Dairanieh IS , Absi-Halabi M , Ali AM 
Published: January 2010

Abstract
Sulfonated melamine-formaldehyde polycondensates, prepared according to a novel procedure, were tested and evaluated as concrete superplasticizers. The effect of cement type and brand, airentraining agents, and retarders on the performance of these admixtures in concrete was studied. The effect of curing medium and curing time on the performance of these materials was also evaluated. These novel admixtures were evaluated and compared with commercially available melamine-based superplasticizers. Results show that the various additives used have no effect on the performance of these resins. The resins outperformed commercial melamine-based superplasticizers by 10 to 20% in compressive strengths of concrete and 20 to 40% in the case of concrete workability.
Effects on Flexural Performance of Sawing Plain Concrete and of Sawing and Other Methods of Altering the Degree of Fiber Alignment in Fiber-Reinforced Concrete
Authors: Johnston CD 
Published: January 2010

Abstract
The bulk of the paper deals with a comparison of the flexural performance of 102-mm (4-in.)-square standard molded specimens with corresponding specimens of the same size produced either by sawing the bottom (tension) surface of a 102 by 152-mm (4 by 6-in.) cross section or by sawing the bottom and sides of a 152 by 152 mm (6 by 6-in.) cross section. The performance of plain concrete is discussed in terms of its flexural strength under third-point loading [ASTM Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading) (C 78)]. The conclusion is that sawing need not adversely affect the measured strength when done carefully with proper equipment. The performance of fiber-reinforced concrete is discussed in terms of changes in first-crack strength and toughness parameters defined according to ASTM Test Method for Flexural Toughness and First-Crack Strength of Fiber-Reinforced Concrete (Using Beam with Third Point Loading) (C 1018). The majority of the results deal with changes in those parameters that are associated with differences in fiber alignment between the molded and sawed specimens. The results of two other small studies involving differences in fiber alignment are also included. In the first, alignment is varied by inserting steel plates in the freshly mixed concrete during consolidation, and in the second by using the same length of fiber in 102-mm (4-in.) and 152-mm (6-in.) cross sections. The conclusion is that preferential fiber alignment by the mold surfaces can increase first-crack strength and toughness indices. To avoid undue influence of fiber alignment in small specimens on flexural test data determined in accordance with Method C 1018, the ratio of minimum specimen cross section to fiber length should not be less than 3.0, except perhaps when strict compliance with this criterion means using specimens larger than 152 mm (6 in.) square.
On Testing of Very Short Concrete Specimens
Authors: Chung H-W 
Published: January 2010

Abstract
For evaluation of concrete strength, the use of concrete cores with the length/diameter ratio less than unity is not allowed at present. Comparative tests on molded cylinders with a varying length/diameter ratio ranging from 0.4 to 2 have been carried out. The experimental investigation has indicated that very short specimens do not yield more variable results than longer specimens and are not more susceptible to the effect of end preparation either by grinding or capping. Based on the empirical results obtained, the formula for the strength correction factor for short cores previously proposed by the author is modified so as to apply to cores with the length/diameter ratio less than unity.
Freeze-Thaw Testing of Coarse Aggregate in Concrete: Procedures Used by Michigan Department of Transportation and Other Agencies
Authors: Vogler RH , Grove GH 
Published: January 2010

Abstract
The procedures used to evaluate the durability of coarse aggregate in concrete by freezing and thawing were determined by a survey. Results indicate that a number of state transportation agencies use freeze-thaw procedures in place of, or in addition to, sulfate soundness and other tests. However, each agency's procedure has unique aspects. ASTM Test Method for Resistance of Concrete to Rapid Freezing and Thawing (C 666) describes the procedures for freeze-thaw cycling and gives partial information on expressing test results, but ASTM has no standard procedure to guide the testing agency in important aspects such as: aggregate grading, aggregate moisture treatment and pretreatment, and concrete mixture proportioning (including cement content, air content of concrete, or curing procedure). The ASTM C 666 method of expressing results for change in length does not permit comparison between different aggregates. The information in this paper is intended to assist ASTM Committee C9 on Concrete and Concrete Aggregates in preparing a practice for evaluation of coarse aggregate in concrete by freezing and thawing.