bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synergistic Roles of Slag and Silica Fume in Very High-Strength Concrete
Authors: Sarkar S , Aitcin P-C , Djellouli H 
Published: January 2010

AbstractA very high-strength concrete (W/C = 0.20) containing 10% silica fume, 30% slag replacement for cement, and a high-range water-reducing admixture attained a compressive strength of 94 MPa at 28 days. The microstructural development of this concrete was studied from 1 to 28 days with SEM/EDXA and TEM. The slag used was reactive, with 70% melilite group phases and an index of hydraulicity of 1.2. Microstructural changes occurring in the first 28 days are presented. The factors responsible for promoting strength are also discussed.
Comparison of Slump Cone and V-B Tests as Measures of Workability for Fiber-Reinforced and Plain Concrete
Authors: Balaguru P , Ramakrishnan V 
Published: January 2010

Abstract
In this paper, two popular measures of workability, namely, slump and V-B time, are compared for plain and steel (hooked) fiber-reinforced concrete. The results are based on experiments made on both types of concrete with and without high-range, water-reducing admixture. The fibers were 50 mm (2 in.) long with deformed ends glued together side by side into bundles (collated) with a water-soluble glue. The W-C ratio varied from 0.3 to 0.62. The air content ranged from 2 to 12%. In terms of workability, the whole spectrum ranging from no slump concrete to flowing concrete was covered.
Based on the results of this investigation, the following general equation can be written relating V-B time and slump log10(V∙B)=a−b(slump)
The addition of high-range water reducer and fibers influences the relationship and hence the constants a and b. The slope of the line, b, is highest for plain concrete without high-range, water-reducing admixture and lowest for fiber-reinforced concrete. In the case of plain concrete, the addition of high-range water reducer seems to result in a more cohesive mixture. As a result, V-B times can be recorded for slumps as high as 163 mm (6.4 in.). Without the addition of the admixture, concrete seems to collapse around a slump of 89 mm (3.5 in.). The addition of fibers increases the cohesiveness of the mixture considerably. For fiber-reinforced concrete made using high-range water reducer, V-B time could be measured for slumps as high as 221 mm (8.7 in.). Generally for a given slump, fiber-reinforced concrete has a higher V-B time than plain concretes.
A Systematic Method to Determine Optimal Specimen Geometry for Measuring Concrete Fracture Properties by the Peak-Load Method
Authors: Yang S , Tang T 
Published: January 2010

Abstract
The peak-load method is a simple method for determining the fracture properties KIcS and CTODc of the two-parameter fracture model of concrete. With this method, the fracture properties can be determined from the measured peak loads of several different (or distinct) specimens. Specimens can be made distinct in specimen shape, size, notch length, and loading configuration. To quantitatively identify the degree of specimen distinction, a variable named specimen distinction number is proposed. When test specimens are considerably distinct, random experimental errors have negligible effect, and determination KIcS and CTODc is of high accuracy. Thus test specimens can be optimized to obtain the most accurate values of the fracture properties. A previous experimental program found that change in specimen shape (e.g., a hole drilled at the axis of splitting tension cylinder) can largely expand the specimen distinction. An experimental program reported in this paper shows that changing loading configurations of beams (or prisms) from bending to eccentric compression can also largely enhance the specimen distinction and therefore provide KIcS and CTODc determination of high accuracy.
Multi-Laboratory Study of the Accelerated Mortar Bar Test (ASTM C 1260) for Alkali-Silica Reaction
Authors: Rogers CA 
Published: January 2010

Abstract
The accelerated mortar bar test, developed by the National Building Research Institute (NBRI) in South Africa, has been adopted in North America for the rapid identification of potentially alkali-silica reactive aggregates and may also be used for assessing the effectiveness of supplementary cementing materials. The purpose of the multi-laboratory studies, involving 46 and 32 laboratories, was to obtain data to develop a multi-laboratory precision statement for the test. The aggregates used in this study were Spratt siliceous limestone from a quarry in Ottawa, and a natural glacio-fluvial sand from north of Toronto in Ontario.
The natural sand gave an average expansion of 0.164% at 14 days and the quarried stone gave an average expansion of 0.417%. The multi-laboratory standard deviation after removal of outliers was found to be proportional to the amount of expansion. The average coefficient of variation at 14 days was found to be about 15% in the two studies.
The use of a single cement by all laboratories did not give a major improvement in precision. Autoclave expansion, and the alkali, sulfate and magnesium oxide (MgO) contents of cement were not related to mortar bar expansion at 80°C. A relationship was found between MgO content and autoclave expansion.
It is possible to prepare a precision statement as follows: For mortars giving average expansions after 14 days in solution of greater than 0.1% the multi-laboratory coefficient of variation (1s% of ASTM C 670) has been found to be 15.2%. Therefore, the results of two properly conducted tests in different laboratories on specimens of a sample of aggregate should not differ by more than 43% (d2s% of ASTM C 670) of the mean expansion.
Relationship Between Gas Adsorption and the Shrinkage and Creep of Recycled Aggregate Concrete
Authors: Gómez-Soberón JMV 
Published: January 2010

Abstract
In this work, an experimental analysis is described of specimens of recycled concrete (RC) made with replacement of natural aggregate with recycled aggregate originating from concrete (RCA). An experimental analysis to obtain the shrinkage and creep properties (basic and by drying) of RC was performed. The replacement fraction of natural aggregate with RCA were 0 %, 15 %, 30 %, 60 % and 100 % and the test conditions were 50 % RH and 20 °C. The results of these trials were compared with mercury intrusion porosimetry (MIP) and gas adsorption (nitrogen) tests, at 90 days. In the results, an increase in the shrinkage and creep properties of the RC with respect to conventional concrete was observed, while porosity values increased. However, the deformation evolution over time is similar to conventional concrete.
Crack Offset Corrections to Post-crack Performance Parameters Obtained from Third-point Loaded Fiber Reinforced Shotcrete Beams
Authors: Bernard ES , Tutlu E , Diamant1idis D 
Published: January 2010

Abstract
Fiber Reinforced Shotcrete (FRS) is used as an economically competitive method of ground support in tunnel excavations throughout the world. Fibres are incorporated into this material to impart post-crack load capacity. Beam tests are commonly used to assess the post-crack performance of FRS but high within-set variability has hindered the usefulness of beam test data. A method of correcting performance data to account for the offset between the position of the crack and the center of the beam has been suggested as a means of improving within-batch variability for post-crack performance parameters obtained from third-point loaded beam tests. In this paper, an offset correction method has been applied to a large set of beam test data obtained as part of Quality Control testing for a tunnel-lining project to determine whether the method is effective in reducing within-batch variability.
Simple Field Tests to Characterize Fluidity and Washout Resistance of Structural Cement Grout
Authors: Khayat KH , Yahia A 
Published: January 2010

Abstract
The ability to assess rheological properties of neat cement grout, such as those used in structural repair and for filling post-tension ducts, is of special interest for the evaluation of the ease of pumping, spreading into place, and filling of narrow spaces. There is an increasing need to identify dependable and simple test methods that can characterize the consistency of specialty cement grouts and reflect variations in rheological properties during handling and placement. Several tests can be used to evaluate the rheological characteristics of a cement grout suspension, including precise methods for the determination of rheological parameters and simple procedures to assess fluidity. Rheological properties can be accurately determined by using a coaxial cylinder viscometer. However, the use of such a viscometer is mainly limited to the laboratory, and simple methods including the mini-slump spread and the modified Marsh cone tests are usually employed in the field to verify the consistency for quality control.
This paper attempts to establish relationships between rheological parameters and fluidity values obtained using simple test methods. Relationships are also determined between the wash-out resistance of structural cement grout and various fluidity and rheological parameters. The derived relationships are based on a wide variety of cement grouts covering up to 210 data points. The various grouts were prepared with W/C ranging between 0.30 and 0.50, Type I and III portland cements, as well as various silica fume replacement values (up to 8% by mass), blast-furnace slag contents of 20 to 60%, fly ash substitutions of 10 to 30%, and limestone filler replacements of up to 30%. The investigated grouts incorporated melamine- and naphthalene-based high-range water reducer, welan gum and cellulose-based viscosity-modifying admixtures, as well as set-retarding admixture.
Test results highlight the difficulties of relying on a single empirical test to evaluate the fluidity of a given grout. Correlations between various simple measurements of fluidity and wash-out mass loss and apparent viscosities determined at different shear rates indicate that the mini-slump and wash-out mass loss measurements correspond well to viscosities determined at low-shear rates (5.1 s-1). In contrast, the modified Marsh cone measurement corresponds well to viscosity determined at high-shear rates ranging between 340 and 510 s-1. Because of the pseudo-plastic behavior of structural cement grouts, field quality control tests should include fluidity assessment at low and high shear rates to adequately evaluate the rheological behavior of the grouts.
Effect of Thermal Variations on Bond Strength of Fusion-Bonded Epoxy-Coated Bars
Authors: Elleithy WM , Al-Amoudi OSB , Sharif AM , Maslehuddin M 
Published: January 2010

Abstract
Fusion-bonded epoxy coating is extensively used to enhance the corrosion resistance of reinforcing steel. The bond strength between these bars and the concrete is expected to be less than that of the uncoated bars and it may be further impaired due to prolonged exposure to thermal variations. This investigation was conducted to evaluate the effect of thermal variations, simulating the changes in the night to day temperature, on the bond strength of fusion-bonded epoxy-coated steel reinforcement. The pull-out specimens, prepared using bars of two different sizes and two coating thickness, were exposed to thermal cycling. The critical and ultimate bond strength of the fusion-bonded epoxy-coated bars were compared with that of the uncoated bars. The results indicated a reduction in the critical bond strength between concrete and the fusion-bonded coated bars. Furthermore, the difference between the critical bond strength in the coated and uncoated bars decreased with increasing thermal cycles, indicating that thermal variation has a greater effect on bond strength than the coating thickness.
Expansion of Cements: Cause and Control
Authors: Hauser K 
Published: January 2010

Abstract
PCA Research Bulletin 45 concludes with 14 major points related to the effects of periclase, free lime, and C3A on “Hydration Expansion Characteristics” (the bulletin title), but it does not address the easy remedy available for those plants with inherently high MgO.
This paper discusses one practical solution, developed decades ago for a plant without the option of avoiding high MgO levels in the quarry, as well as a control procedure that will help avoid over-doing the chemical modification required and contribute to better uniformity.
The Permeability of Cement Systems to Chloride Ingress and Related Test Methods
Authors: Liu Z , Beaudoin JJ 
Published: January 2010

Abstract
The rapid chloride permeability test (AASHTO T277/ASTM C 1202) and other chloride permeability testing methods are critically reviewed. The basic concepts of concrete permeability and conductivity are also discussed. An attempt at clarification and resolution of some issues is made. A faster and simpler alternative testing method to the AASHTO T277/ASTM C 1202 based on the a-c impedance techniques is proposed. It provides at least an equivalent indication of the concrete permeability with respect to AASHTO T277/ASTM C 1202 and is without several shortcomings characteristic of the current methods.
Introduction to the Symposium on Developments in Test Methods for Alkali-Silica Reaction
Authors: Lane DS , Lobo C 
Published: January 2010

Abstract
The following papers in this issue were presented at an ASTM Committees C01 and C09 Symposium on Developments in Test Methods for Alkali-Silica Reaction held in December 1998 in Nashville. The symposium was organized at the suggestion of Leslie J. Struble, chairman of Subcommittee C09.26, Chemical Reactions.
Limits on Alkali Content in Cement—Results from a Field Study
Authors: Leming ML , Nguyen BQ 
Published: January 2010

Abstract
ASTM C 150 has optional limits on the equivalent alkalies in portland cement expressed as %Na2O + 0.658 × %K2O), often referred to as “Na2Oeq” where alkali silica reactivity is a potential problem. The prescribed limit of 0.6% by mass of the cement, which was developed over 40 years ago, has been questioned as not being sufficiently restrictive in some circumstances.
A 17-year-old bridge showing strong evidence of alkali-silica reactivity was studied as part of a larger investigation for the North Carolina Department of Transportation. The extent of noticeable map cracking was significantly different in different parts of the bridge. The differences could not be explained in terms of exposure to moisture or other environmental effects. Available information indicated that two different cements, with different alkali contents, were probably used at different times during construction.
Cores were removed from areas with obvious differences in cracking. All of the cores contained a reactive phyllite coarse aggregate. The alkali content was determined from selected cores. In addition, the area of material that fluoresced under ultraviolet light after treatment with uranyl acetate was determined on cores that had been split longitudinally. These factors were compared to the extent of cracking. No deleterious ASR was generated when the water-sol-uble alkali content was less than 1.5 kg/m3, or 0.55% by mass of the portland cement (Na2Oeq) with the reactive phyllite, at least for concrete in service for 17 years. A higher alkali content resulted cracking due to ASR.
Proposed New Test Procedure for Measuring Alkali-Silica Expansion Produced by Hydraulic Cement
Authors: Struble LJ , Pade C 
Published: January 2010

Abstract
Although there are several standard tests for measuring alkali-silica expansion produced by an aggregate, there is only one test suitable for measuring expansion produced by the cementitious material (C 441, Standard Test Method for Effectiveness of Mineral Admixtures of Ground Blast-Furnace Slag in Preventing Excessive Expansion of Concrete Due to the Alkali-Silica Reaction). This mortar test uses Pyrex glass as the standard reactive aggregate. A new test has been developed to overcome these deficiencies. Also a mortar test, it utilizes Vycor glass rather than Pyrex glass and a procedure that does not produce condensation on the bars, which causes leaching of alkalies from the mortar. The test has recently been adopted by ASTM as a provisional standard to determine whether hydraulic cement produces deleterious expansion when combined with alkali-reactive aggregate in concrete.
Field Study of the Setting Behavior of Fresh Concrete
Authors: Abel JD , Hover KC 
Published: January 2010

Abstract
A simple test is introduced for monitoring setting behavior of concrete in the field. The method was inspired by the ASTM C 403 penetration resistance method for mortar setting time, coupled with the recommendation of ACI Committee 302 (Concrete Floors) that bull-floated flatwork surfaces are ready for subsequent finishing operations when a worker standing on the fresh concrete leaves a boot print about 6 mm (¼ in.) deep. In the proposed test a penetrometer probe was fabricated with a contact area approximately equal to the contact area under an adult-sized work boot. Setting is monitored by measuring the pressure required to embed the probe into the concrete surface to a depth of 6 mm (¼ in.). The method was used during construction of a pedestrian mall, and the results provide insight into the nature and variability of the setting behavior of concrete, and on the relationship between setting of concrete and the setting of mortar.
Specimen and Aggregate Size Effect on Concrete Compressive Strength
Authors: Issa SA , Islam MdS , Issa MA , Yousif AA , Issa MA 
Published: January 2010

Abstract
Test results obtained on the effect of specimen size and aggregate size on concrete compressive strength and modulus of elasticity are presented. The concrete was prepared using 4.75, 9.5, 19.0, 37.5, and 75-mm nominal maximum size aggregate. Over 600 cylinders were cast and tested for concrete compressive strength and modulus of elasticity. Four different sizes of plastic cylinder molds were used: 150 by 300 mm, 100 by 200 mm, 75 by 150 mm, and 50 by 100 mm. The testing was carried out in accordance with ASTM standards for concrete compressive strength (ASTM 39) and modulus of elasticity (ASTM C 469).
The test results were presented in terms of the concrete modulus of elasticity-to-compressive strength ratio (E/f′c) versus cylinder diameter, maximum aggregate size, age at testing, among other factors. The results revealed that a size effect exists. The strength ratio was higher for the larger nominal maximum aggregate size concrete at each testing date. Hence, as the nominal maximum aggregate size decreased, the strength ratio decreased. The strength ratio followed a dished trend with respect to specimen size. For each cylinder size, as the nominal maximum aggregate size increased, the coefficient of variation increased. It was also found that for the same nominal maximum aggregate size specimens, the coefficient of variation increased as the cylinder size decreased.
Modified Washington Hydraulic Fracture Test to Determine D-Cracking Susceptible Aggregate
Authors: Issa MA , Issa MA , Bendok M 
Published: January 2010

AbstractIn the Strategic Highway Research Program (SHRP) a test method for identifying D-cracking susceptible aggregates in approximately eight days was developed to replace the widely used but time-consuming rapid freezing-and-thawing test using ASTM C 666 test methods. The basic assumption in this new method is that the hydraulic pressure expected in concrete aggregates during freezing and thawing can be simulated by subjecting aggregates, submerged in water, to high pressures and the extreme rapid release of the pressure. The percent fracture, percent mass loss, and hydraulic fracture index are the parameters calculated as a result of the test, which is commonly called the Washington Hydraulic Fracture Test (WHFT). A number of states have conducted tests using this apparatus on the same aggregate source and have found a scatter in the results. These reports prompted research on a newer modified apparatus that accounts for this variability by allowing for a larger specimen and/or sample size and also introducing a computer interface. The WHFT 97 is completely automated in terms of controlling the testing procedure for each respective ten cycles of operation, and requires minimal manual labor.Twenty-one different aggregate sources, with different degrees of freezing and thawing susceptibility, were tested according to the WHFT test procedure on both machines (the original WHFT 94 and the WHFT 97) to establish a correlation, if possible, between the results of the proposed WHFT test and those reported for the ASTM C 666 Method B as modified by the Illinois Department of Transportation (ILDOT). In addition, a petrographic analysis was conducted on each aggregate source in order to determine its percentage of air voids, pore size, and pore size distribution. A direct correlation was not established; hence, the test data were compared using the pass/fail criteria to establish the potential of the UIC Modified WHFT 97 as a screening test. The failure criteria presented by the percent fracture (2%) from the WHFT 97 test and 0.060% maximum allowable expansion from the ILDOT freezing and thawing test were used. This comparison indicated that 67% of the test results on the WHFT 94 and 76% on the WHFT 97 were identified correctly based on the ILDOT criteria. All the aggregate types (dolomite, gravel, ACBF slag) were successfully classified using these failure modes with the exception of one aggregate type, limestone. It appears, based on this comparison, that the WHFT 97 test may have the potential to be used as a screening test prior to the ASTM freezing and thawing test. In addition, the petrographic investigation showed potential in rating limestone aggregate as well as determining if other testing is required to identify D-cracking susceptible aggregate.
Quantitative Description of Coarse Aggregate Volume Fraction Gradients
Authors: Picka JD , Jaiswal SS , Igusa T , Karr AF , Shah SP 
Published: January 2010

Abstract
Within any cast cylinder of concrete, the coarse aggregate will tend to be inhomogeneously distributed. This variability may arise as a result of segregation caused by gravity or as a result of the wall effect that is caused by the inability of the aggregate to penetrate the walls of the mold. Using methods from image analysis, stereology, and statistics, local estimates of aggregate inhomogeniety are defined that quantify phenomena that have been qualitatively described in the past. These methods involve modification of the two-dimensional images to prepare them for analysis, as well as simple diagnostic statistics for determining the presence of a wall effect. While the techniques presented herein are developed specifically for cast cylinders, they can be generalized to other cast or cored concrete specimens.