bluuebunny/crossref_metadata_2025 huggingface dataset:
A systematic model for evaluating the patient aspects of health technologies
Authors: Koivisto Juha , Anttila Heidi , Ikonen Tuija , Reiman-Möttönen Päivi
Published: January 2010

Health technology assessment (HTA) is generally defined as a multidisciplinary research field that aims to produce objective knowledge for decision makers on the benefits, costs and harms of a technology. This paper describes an attempt to develop a systematic relational model for the evaluation of the patient aspects of health technologies, and in particular employs actor-network theory (ANT), with its emphasis on a non-linear innovation process, translations, co-production of technology and context and socio-material networks. It first considers the ontological and other presumptions of mainstream HTA and suggests an alternative relational ontology and approach. It then analyses the patient aspects of health technology by defining its scope and other issues that may provide a general framework for studying and evaluating the patient aspects of health technology. It then briefly discusses the implications of the relational approach in regard to the empirical practice of the whole HTA.
Endoprotease Profiling with Double-Tagged Peptide Substrates: A New Diagnostic Approach in Oncology
Authors: Peccerella Teresa , Lukan Nadine , Hofheinz Ralf , Schadendorf Dirk , Kostrezewa Markus , Neumaier Michael , Findeisen Peter
Published: January 2010

Background: The measurement of disease-related proteolytic activity in complex biological matrices like serum is of emerging interest to improve the diagnosis of malignant diseases. We developed a mass spectrometry (MS)-based functional proteomic profiling approach that tracks degradation of artificial endoprotease substrates in serum specimens.

Methods: The synthetic reporter peptides that are cleaved by tumor-associated endopeptidases were systematically optimized with regard to flanking affinity tags, linkers, and stabilizing elements. Serum specimens were incubated with reporter peptides under standardized conditions and the peptides subsequently extracted with affinity chromatography before MS. In a pilot study an optimized reporter peptide with the cleavage motif WKPYDAADL was added to serum specimens from colorectal tumor patients (n = 50) and healthy controls (n = 50). This reporter peptide comprised a known cleavage site for the cysteine-endopeptidase “cancer procoagulant.”

Results: Serial affinity chromatography using biotin- and 6xHis tags was superior to the single affinity enrichment using only 6xHis tags. Furthermore, protease-resistant stop elements ensured signal accumulation after prolonged incubation. In contrast, signals from reporter peptides without stop elements vanished completely after prolonged incubation owing to their total degradation. Reporter-peptide spiking showed good reproducibility, and the difference in proteolytic activity between serum specimens from cancer patients and controls was highly significant (P < 0.001).

Conclusions: The introduction of a few structural key elements (affinity tags, linkers, d-amino acids) into synthetic reporter peptides increases the diagnostic sensitivity for MS-based protease profiling of serum specimens. This new approach might lead to functional MS-based protease profiling for improved disease classification.
Association of Apolipoprotein B with Incident Type 2 Diabetes in an Aboriginal Canadian Population1
Authors: Ley Sylvia H , Harris Stewart B , Connelly Philip W , Mamakeesick Mary , Gittelsohn Joel , Wolever Thomas M , Hegele Robert A , Zinman Bernard , Hanley Anthony J
Published: January 2010

Background: Expanding evidence indicates that apolipoprotein B (apo B) is superior to LDL cholesterol as a marker of vascular disease. Although traditional lipid measures are known to predict type 2 diabetes, limited data are available regarding apo B. We assessed the association of apo B with incident type 2 diabetes and compared it with traditional lipid variables as a risk predictor in aboriginal Canadians.

Methods: Of an initial cohort of 606 individuals without diabetes in 1993–1995, 540 were contacted for the 10-year follow-up evaluation in 2003–2005. Fasting and 2-h postload glucose concentrations were obtained at baseline and follow-up to determine incident type 2 diabetes. Baseline fasting serum lipids were measured with standard laboratory procedures.

Results: The cumulative 10-year incidence of type 2 diabetes was 17.5%. High concentrations of apo B, triglycerides, and LDL cholesterol, and low concentrations of HDL cholesterol were individually associated with incident type 2 diabetes in univariate analyses. Comparing C statistics of univariate models showed apo B to be a superior determinant of incident diabetes compared with LDL (P = 0.026) or HDL (P = 0.004) cholesterol. With multivariate adjustment including waist circumference, apo B (odds ratio, 1.50; 95% CI, 1.11–2.02) and triglycerides (odds ratio, 1.49; 95% CI, 1.12–1.98) remained associated with incident diabetes, whereas LDL and HDL cholesterol became nonsignificant.

Conclusions: The association of plasma apo B with incident type 2 diabetes and its better prediction of risk compared with LDL or HDL cholesterol suggest the potential for the use of apo B in type 2 diabetes risk communication and prevention.
Frost Deicer Salt Scaling Testing of Concrete: Effect of Drying and Natural Weathering
Authors: Jacobsen S , Marchand J , Boisvert L , Pigeon M , Sellevold EJ
Published: January 2010

Laboratory deicer salt scaling of concrete is very sensitive to prior drying and resaturation, weathering, or aging. Previous investigations have shown both positive and negative effects. The object of this investigation was to quantify the effect of pre-conditioning on scaling test results and to provide data for the relationship between laboratory testing and field exposure. Four concretes with W/B = 0.45 and various binders and air void systems were subjected to a range of different pre-treatments. These included a variety of RH, temperature, and wind combinations that resulted in a variety of evaporation rates from free water surface. Other pre-treatments were no drying (virgin condition) and natural weathering for 3 months and 1 year in Québec City. Subsequent resaturation with water and scaling testing with 3% NaCl confirmed that mild drying gives lower scaling than both virgin condition and severe drying. Natural weathering resulted in scaling of the same magnitude as that of mild drying, indicating that the standard mild laboratory drying at 50% relative humidity and 20°C is suitable. The protective effect of the air voids is considered activated after mild drying, vanishes after more severe drying, and not affected by natural weathering. Water filling of air voids during wet curing can be the cause of the high scaling on virgin concrete. 5% silica fume reduced the effect of weathering and drying, and gave lower scaling than OPC concrete. Wet freeze/thaw gives high uptake of liquid compared to capillary absorption and therefore rather severe test conditions.
Prevention of Damage Due to Alkali-Aggregate Reaction (AAR) in Concrete Construction—Canadian Approach
Authors: Thomas MDA , Hooton RD , Rogers CA
Published: January 2010

This paper outlines the philosophy behind the 1994 revision of the Canadian Standards Association guidelines for preventing the risk of damage due to alkali-aggregate reaction (AAR) in new construction. Aggregates may be selected based on documented previous field performance, petrographic examination, or satisfactory performance in a sequence of accelerated and long-term expansion tests. If the aggregate is deemed not deleteriously reactive by one of these methods, it may be used in concrete with no further precautions. Potentially alkali-silica reactive aggregates may be considered for use in concrete provided appropriate preventive measures are taken to reduce the risk of damaging expansion. Recommended measures are: (1) limiting the total alkali content of the concrete (from portland cement and other sources) and (2) the use of supplementary cementing materials (SCMs), such as fly ash or slag. Minimum replacement levels are given for fly ash (20 to 30% depending on composition) and slag (50%). If these SCMs are to be used at lower replacement levels or at high concrete alkali levels, concrete-prism testing is required to assure the efficacy of the reduced amount of SCM in controlling expansion with the proposed aggregate. As yet, there is no specific guidance for using silica fume with reactive aggregates. Advice regarding alkali-carbonate reactive aggregates is restricted to selective quarrying and beneficiation to exclude the reactive material.
Use of Ultrasonic Pulse Velocity for Fracture Testing of Cemented Materials
Authors: Alexander MG
Published: January 2010

The paper describes the use of the ultrasonic pulse velocity technique to measure two important features of fracture in notched concrete beams: the extent of the zone of microcracking that develops ahead of the notch or crack, and the depth of the main (or stress-free) crack. Beams of 100 mm in width and ranging from 100 to 500 mm in depth were tested, and ultrasonic pulses were transmitted longitudinally through the beams at various elevations. Ultrasonic readings taken at elevations above or below the visible crack tip were found to be sensitive to the development of the microcracked zone or to main crack growth, respectively. Based on pulse transit time measurements, the average depth of the microcracked zone was about 44% of the residual beam depth, taking all the beam sizes together. Crack depths estimated from pulse transit times were found to agree with visible crack depths to less than 10% on average.
Modification of the X-Radiography Technique to Include a Contrast Agent for Identifying and Studying Microcracking in Concrete
Authors: Najjar WS , Hover KC
Published: January 2010

The utility of X-radiography for the study of microcracking in concrete is significantly enhanced by impregnating cracks and voids with a lead-nitrate contrast agent. When an X-ray flux is passed through a polished concrete specimen, X-rays are readily attenuated by the contrast agent in the cracks, which produces a sharp tonal contrast in the resulting radiograph between cracks and surrounding concrete. Radiographs obtained using this technique are compared with more conventional X-ray images of the same specimens. This method is similar in concept to neutron radiography, in which a neutron-attenuating contrast agent is used for enhancing crack images.
Analytical Investigation of the Influence of Air Bubble Size on the Determination of the Air Content of Freshly Mixed Concrete
Authors: Hover KC
Published: January 2010

It has been qualitatively suggested that the pressure method for the determination of air content in freshly mixed concrete can be in error when a portion of the entrained air bubbles becomes relatively incompressible due to the increase in internal bubble pressure which accompanies a reduction in bubble diameter. This has been used to explain the observed discrepancy between air meter readings and the air volume reported by microscopic analysis. This paper reports the results of an analytical investigation of the bubble-size effect, in which it is seen that it is unlikely that a sufficient volume of bubbles with the required diameter are present so as to cause the observed discrepancy. In order to demonstrate a significant influence of bubble size on the accuracy of the air meter, one must resort to values for the surface tension of the bubble film which are unjustified. The characteristics of various meters are discussed.
Effect of Air-Entraining Agent on Air-Void Parameters of Low- and High-Calcium Fly Ash Concretes
Authors: Rodway LE
Published: January 2010

Five fly ashes with widely varying lime contents from three countries were used for 25% of the cement by mass in identical concrete mixes, including the same quantity of air-entraining agent in each case. The hardened concrete resulted in a satisfactory air-void system in terms of freezing-thawing resistance, regardless of the lime content of fly ash.
Fatigue Behavior of Superplasticized Concrete
Authors: Lee D-Y , Yang JJF , Klaiber FW
Published: January 2010

Although many studies have been conducted on the physical properties of superplasticized concrete, very little research has been reported on the fatigue properties of superplasticized concrete. The purpose of this study was to determine the fatigue properties of concretes with superplasticizers and compare these properties with those of concrete without superplasticizers.

More than 120 concrete specimens at three levels of water/cement ratio, and two levels of cement content, with and without superplasticizers, were subjected to compressive fatigue loading in which the stress varied from essentially zero to a predetermined maximum stress as percentages of the compressive strength.

For plain concrete, the fatigue strength of superplasticized concrete was not significantly different from that of nonsuperplasticized concrete. Also, water/cement ratio in the range of 0.4 to 0.6 did not appreciably affect the fatigue strength of superplasticized concretes.
Neoprene Pads for Capping Concrete Cylinders
Authors: Ozyildirim C
Published: January 2010

This study investigated the feasibility of using neoprene pads confined by steel end caps instead of sulfur-mortar caps in compressive strength tests on 150- by 300-mm (6- by 12-in.) concrete cylinders. The 13-mm (½-in.) thick neoprene pads had a 50 durometer hardness and were cut to fit in the end caps, which had an inside diameter of 159 mm (6¼ in.) with a tolerance of +0 and −2 mm (−1/16 in.). Compressive strength data were obtained from 438 pairs of cylinders prepared in the field from commercial batches of concrete. One cylinder of each pair was tested with neoprene pads and the other with sulfur-mortar caps. Although the results indicate statistically significant differences in the values obtained by the two capping methods, the differences are considered negligible from a practical standpoint. A linear regression analysis indicated a good correlation between the two methods.
Application of CCRL Data in the Formulation of Precision Estimates for Selected Cement Standards
Authors: Pielert JH , Haverfield JW , Spellerberg PA
Published: January 2010

Test precision statements are frequently used in evaluating the quality of test results used to judge the acceptibility of materials. This paper provides an overview of the activities of the Materials Reference Laboratories at the National Bureau of Standards and demonstrates how data from the reference sample programs can be analyzed to formulate precision estimates that can then be used to develop precision statements for ASTM test methods. Precision estimates derived from the analysis of CCRL portland, blended, and masonry reference sample data are presented for selected cement tests.
Improved Utilization of Fly Ash in Concrete Through a Chloride-Free Accelerator
Authors: Popovics S
Published: January 2010

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

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

Alkali-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

To 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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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.
Some Recent Problems with Air-Entrained Concrete
Authors: Hover KC
Published: January 2010

Several problems are identified in regard to air-entrained concrete, which include the accuracy of the pressure air meter (ASTM C 231), the accumulation of air voids at the coarse aggregate surface, excessive loss of air volume in transit or in pumping, and the need for greater precision and detail in specification requirements for air-entrained concrete. Data are presented from four recent construction projects from a wide geographical range in the United States.
Effect of Curing Conditions on the Compressive Strength and Elastic Modulus of Very High-Strength Concrete
Authors: Asselanis JG , Aitcin P-C , Mehta PK
Published: January 2010

With ordinary concrete, although a water content corresponding to about 0.3 water/cement ratio by weight is adequate for complete hydration of portland cement, in practice water/cement ratios in the range of 0.5 to 0.7 are used to achieve proper workability. Thus, ordinary concrete shows rather low strength and high permeability at early ages. With the progress of cement hydration reactions, both strength and impermeability show dramatic improvement as the products of hydration fill up the empty or water-filled spaces present in the cement paste.
Basic Creep Formula for Aging Concrete: Sinh-Double Power Law
Authors: Bažant ZP , Chern J-C , Wu Y-G
Published: January 2010

An alternative simple formula for the compliance function for basic creep of concrete is proposed and evaluated. It consists of a hyperbolic sine combined with the double power law. For short creep durations it asymptotically approaches the double power law, and for very long durations it asymptotically approaches the logarithmic law, which is the same behavior as for the previously formulated log-double power law. The formula allows a good fit of basic creep data from the literature. It represents them as well as the log-double power law and better than the double power law, although the difference is not large. Compared to the double power law, a significant improvement is obtained in the final slope of the creep curves. Compared to the log-double power law, the proposed formula is somewhat better for extension into the short-time dynamic range.
A Damage Model for Sulfate Attack of Cement Mortars
Authors: Ouyang C
Published: January 2010

A model for cement mortars under sulfate attack is proposed based on a progressive fracturing concept. An initial damage of mortar is defined as a function of the Powers' gel space ratio. The sulfate attack evidenced by the expansion of the matrix is incorporated as additional nucleated voids which increase the initial damage existing before the loading. The compressive properties of cement mortars under sulfate attack are predicted well by this model. Expansion limits for sulfate attack computed by this model agree well with those proposed by Mather and Patzias.
Statistical Characteristics of New Pin Penetration Test
Authors: Carino NJ , Tank RC
Published: January 2010

Researchers at the University of Saskatchewan have developed a new test for estimating the in-place strength of concrete. The method, known as the pin penetration test, involves driving a small pin into the concrete surface using a spring-loaded driver. The penetration of the pin creates a small indentation whose depth is measured. The pin penetration is inversely related to the strength of concrete. This paper provides information about the within-test variability of the method and about the correlation relationship between compressive strength and pin penetration. Test results show that a standard deviation with a value of about 0.015 in. (0.038 mm) describes the within-test variability. The correlation relationship is nonlinear for compressive strengths between 1000 and 5800 psi (6.9 to 40.0 MPa) and depends on the water-cement ratio of the concrete. For compressive strength less than about 4000 psi (27.6 MPa), the correlation relationship is not strongly dependent on water-cement ratio, and a straight line adequately represents the relationship. However, the correlation relationship obtained in this study differs from that reported by others.
The Morphology of Air-Entrained Voids, at Early Age
Authors: Rashed AI , Monteiro PJM , Williamson RB , Bastacky J
Published: January 2010

The morphology of air-entrained voids has been observed using the low-temperature scanning electron microscope (LTSEM). The entrained voids have been examined in cement paste specimens at an age of 5 min.
Properties of Concrete at Early Ages
Authors: Carino NJ , Jennings HJM , Snell LM
Published: January 2010

What should be done to improve our understanding and appreciation of the properties of concrete at early ages? This question was the basis for an Engineering Foundation Conference on the topic of “The Properties of Concrete at Early Ages.” To answer the above question, the conference participants developed the recommendations summarized in this technical note. The recommendations addressed the need to: gain a better understanding of cement paste microstructure; improve codes and standards; control temperature rise during construction; and educate the users of concrete.
Microstructural Development in a High-Strength Concrete Containing a Ternary Cementitious System
Authors: Sarkar SL , Baalbaki M , Aitcin P-C
Published: January 2010

The sudden upsurge of mechanical strength at 12 h in a silica-fume/fly-ash high-strength concrete led the authors to investigate the cause and to determine the microstructural characteristics of this concrete with progressive hydration from 1 to 91 days to correlate its microstructural development with its strength enhancement pattern.
Improvement of Concrete Strength Statistical Control
Authors: Leshchinsky AM
Published: January 2010

Extensive research is being carried out in the area of concrete strength statistical control. Acceptance control plans are improved to reduce consumer's and producer's risks: the producer's risk consists in rejecting good-quality concrete, while that of the consumer, in accepting a substandard concrete. ACI 318 provides a low-level risk for a producer and a high-level risk for a consumer. It is demonstrated that the consumer's risk substantially decreases with the introduction of the quality assurance system.

The need to provide several acceptance criteria with various required probabilities of specified strength f′c and consumer's allowable risk in national codes is analyzed.

In addition, two procedures are given: the first consists in taking into account the actual concrete strength distribution, and the second, in rejecting gross errors.
Introduction to Symposium on Characterization of Hydraulic Cements
Authors: Hooton RD
Published: January 2010

[The Symposium on Characterization of Hydraulic Cements, held in San Antonio, TX, on 5 Dec. 1990, was sponsored by ASTM Committee C-1 on Cement. Five papers from the symposium are presented in this issue of Cement, Concrete, and Aggregates. R. Doug Hooton, associate professor at the University of Toronto, presided as symposium chairman and Leslie J. Struble served as symposium cochairman. R. Doug Hooton provided this Introduction—Editor.]
Quantitative Clinker Microscopy with the Light Microscope
Authors: Campbell DH , Galehouse JS
Published: January 2010

Microscopical methods for quantitative determination of phase percentage in rocks, bricks, portland cement clinkers, and other composite materials, although time consuming, are among the most reliable techniques available. For particle mounts on glass microscope slides, the line, ribbon, or Fleet methods are used. For thin sections or polished sections, the linear traverse or point-counting methods are recommended. Microscopically determined percentages can obviously include crystalline and amorphous phases, which is more than X-ray diffraction can clearly reveal. Microscopical data can be converted into oxides, giving a chemical analysis. The gathering of microscopical data is facilitated by electronic tallying devices and semiautomatic mechanical stages. Finally, microscopical data, properly gathered, can be treated statistically with high levels of confidence. One should be aware, however, of the limits that each microscopical method entails.
Quantitative Phase Analysis of Clinker Using X-Ray Diffraction
Authors: Struble LJ
Published: January 2010

Many difficulties are encountered in quantitative X-ray diffraction analysis of portland cement and clinker. Despite these difficulties, it appears that, with adequate experimental procedures, the major clinker phases can be determined with an absolute accuracy of 2 to 5% (by weight of the total clinker) for alite and belite and 1 to 2% (by weight of the total clinker) for aluminate and ferrite. A task group in ASTM is exploring X-ray diffraction methods for quantitative phase analysis of cement and clinker. The group has made considerable progress towards proposing a standard test method for aluminate, ferrite, and magnesium oxide. Using specified experimental procedures, preliminary results indicate that these three phases may be determined in clinker with an absolute accuracy of 1.7%. After the task group completes work with these phases, it plans to continue with the calcium silicates.