bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparison of Results from C 441 and C 1293 with Implications for Establishing Criteria for ASR-Resistant Concrete
Authors: Lane DS 
Published: January 2010

Abstract
Several test methods are available to evaluate the potential susceptibility of concrete-making materials to deleterious alkali-silica reactions (ASR). These methods vary in the approaches they use to accelerate the reaction; acceleration being necessary to provide timely evaluations of materials in predicting long-term performance. As a consequence, the tests are not universally applicable, nor do they necessarily provide straightforward, consistent results using established criteria. This paper compares results of C 441 and C 1293 tests in an effort to develop specification criteria for ASR-resistant concrete.
ASTM C 441 uses Pyrex glass aggregate in mortars to accelerate the testing and provides reliable results in 2 months. It can be used to evaluate the effectiveness of pozzolans and ground slag to prevent expansions, as well as the effect of portland cements on the reaction. However, differences in the relative reactivity of Pyrex glass and the aggregates used in concrete construction should be considered in the engineering decision-making process. The C 1293 test has the advantage of testing the natural aggregates available for use in construction and achieves acceleration by artificially raising the alkali content of the concrete. Its disadvantages are that it takes at least 1 to 2 years for results, and cannot be used to evaluate the effectiveness of portland cements in resisting ASR.
C 1293 results can be considered to have more relevance to actual field constructions than results from C 441 tests because it tests construction aggregates. However, the 1 to 2 year testing period makes it impractical for general specification purposes. This paper illustrates the use of C 1293 results to determine which cementitious materials are effective in controlling the reactivity of a particular aggregate, coupled with C 441 testing of those same materials to establish an expansion limit in C 441 tests. The limit established for C 441 tests provides for timely testing that should be applicable to common hydraulic cementitious materials.
Using Accelerated Test Methods to Specify Admixtures to Mitigate Alkali-Silica Reactivity
Authors: Barringer WL 
Published: January 2010

Abstract
The development of accelerated tests for alkali-silica reactivity (ASR) included the investigation of a wide range of aggregates and cements that gave results indicating the potential reactivity of these combinations. The development procedure did not provide for comparison of specific aggregates and cements in areas where ASR is known to be of concern. Through the development of a matrix comparing available materials and their reactions, specifications for concrete proportions may be developed to further alleviate the effects of ASR in a specific area. Tests conducted, using New Mexico aggregates and available admixtures in conjunction with AASHTO Test Method T 303, indicated that fly ash and fly ash/lithium admixtures resulted in significant reduction in expansion of mortar bars.
The matrix for this research involved five fly ash sources, five aggregate sources, one local cement, and a lithium nitrate solution.
Subsequent to this research, the New Mexico State Highway and Transportation Department has implemented the findings into their specifications for infrastructure concrete.
Evaluation of Laboratory Test Methods for Alkali-Silica Reactivity
Authors: Fournier B , Malhotra VM 
Published: January 2010

Abstract
In 1991, the Canada Centre for Mineral and Energy Technology (CANMET) initiated a major research project dealing with preventive measures against alkali-silica reaction (ASR) in concrete. The main objective of the above project is to develop a comparative field and laboratory engineering database on the longterm effectiveness of supplementary cementing materials (SCMs) in controlling and/or reducing expansion and cracking in concrete due to ASR. The results obtained to date indicate that the effectiveness of SCMs in controlling expansion due to ASR is a function of various parameters such as the composition and proportion of the different types of SCMs in concrete (for example, fly ash, slag, silica fume), the total cementitious materials and/or total alkali content in the system, and the reactivity level of the aggregate. Accelerated concrete prism and mortar bar expansion test methods can be used in the laboratory to predict the long-term performance of SCMs in controlling expansion due to ASR.
Anhydrite in High Sulfur Trioxide (SO3)/Alkali Clinkers: Dissolution Kinetics and Influence on Concrete Durability
Authors: Michaud V , Suderman RW 
Published: January 2010

Abstract
Changes in the cement manufacturing process, such as the use of higher sulfur fuels, have tended to raise clinker sulfate levels and sulfur trioxide (SO3) alkali ratios. As one of the consequences, the nature and quantity of the clinker sulfate phases have been modified. Clinker sulfates tend to be available as double sulfate salts; calcium langbeinite instead of potassium sulfate.
Anhydrite is present in the clinker only when the quantity of clinker sulfate is higher than the amount that can be combined by the alkali ions as alkali sulfates and calcium langbeinite. It has been demonstrated recently that in clinkers with sulfate/alkali ratios as high as 3.6, anhydrite is not detectable and only begins to form at levels above this. This is consistent with observations from regular industrial production. Even with fairly high sulfate levels and SO3/alkali ratios, industrial clinkers do not attain high enough SO3/alkali ratios to permit anhydrite formation. Thus, the presence of clinker anhydrite is illusive.
It has been alleged recently that clinker anhydrite would provide nonheat-cured concrete with a lesser durability. The objective of this study is to establish what would be the effect of anhydrite on durability in the hypothetical case that this phase was present in clinker. The impact of clinker anhydrite has been examined on a laboratory clinker with a SO3/K2O ratio of 5.2 and a SO3 level of 3.8%. The laboratory clinker anhydrite amount has been evaluated at 1.1%. Two aspects have been studied: • The dissolution rate of clinker anhydrite present in a very high SO3/alkali clinker during hydration, and • The influence of clinker anhydrite on expansion.
Experiments indicate that anhydrite dissolves and reacts quite quickly, mainly within a few days, and does not produce concrete with expansion. Therefore, clinker anhydrite, if it did exist, would not contribute to ambient temperature DEF.
Delayed Ettringite Formation (DEF) in Structural Lightweight Aggregate Concrete: Effect of Curing Temperature, Moisture, and Silica Fume Content
Authors: Rønne M , Hammer TA 
Published: January 2010

Abstract
The results confirm that the self-desiccation of normal density (ND) high strength concrete may prevent delayed ettringite formation (DEF). However, when using lightweight aggregate (LWA), the initial water content of the LWA grains seems to be sufficient to give some DEF. The results also confirm that the critical temperature, provided that the moisture content is sufficiently high, is in the range of 65 to 70°C for ND concrete with Norwegian cements. The critical temperature for LWA concrete seems to be somewhat higher; above 70°C. The LWA expansion due to DEF seems to be somewhat lower than the expansion of ND concrete, provided they have the same binder and paste quality. The volume increase coincides with an extensive compressive strength reduction. The reported results confirm that addition of silica fume (5%) in combination with the investigated cements, seems to prevent or eliminate the DEF.
Assessing the Distribution of Sulfate in Portland Cement and Clinker and Its Influence on Expansion in Mortar
Authors: Tennis PD , Bhattacharja S , Klemm WA , Miller FM 
Published: January 2010

Abstract
The present work is a continuation of a study previously reported on the characterization and analysis of 33 different clinkers from North American cement plants which varied widely in molar SO3/Na2Oeq, SO3 content, and mineralogical phase distribution. This research examined the distribution of sulfur in a broad range of clinkers and identified its presence as alkali sulfates, alkali calcium sulfates, and as sulfate incorporated in the silicate phases. As a key part of the work, it has been necessary to develop relevant analytical methods for measuring potentially slowly soluble sulfate in clinker phases. The selective dissolution procedures described are applicable to the evaluation of sulfate distribution of both clinker and finished portland cement.
In the current phase of the study, physical measurements are being performed to substantiate the chemical observations of the earlier work. Five cements commercially ground from clinkers characterized earlier were chosen for further evaluation based on various sulfate levels and sulfate/alkali ratios. The volume stabilities of mortar bars (25 by 25 by 255 mm) made with these five cements were determined for several curing conditions: curing and storage under water at 23°C; curing for 24 h at 23°C, with subsequent storage under water at 38°C; 4 h initial curing at 23°C, followed by a 12-h exposure to 70 or 80°C, followed by storage under water at 23°C. The rate of temperature increase or decrease was 20°C/h in all cases. These mortar bars were prepared according to European Standard EN 196-1 with German DIN Standard Sand (Normensand). After 28 weeks of storage, bars appear to have stabilized below about 0.03% expansion. More recent testing has begun using mortar bars prepared with the above cements plus two additional Type III cements commercially ground from two of the same clinkers. These mortars have been prepared with an ASTM C 109 mortar composition and graded standard sand, which will permit direct comparison of ASTM and European standard test procedures.
Role of Fly Ash and Aluminum Addition on Ettringite Formation in Lime-Remediated Mine Tailings
Authors: Mohamed AMO , Hossein M , Hassani FP 
Published: January 2010

Abstract
In this study, experiments were performed to evaluate the formation of ettringite in mine tailings samples treated with lime, fly ash type “C,” and aluminum. The success of the treated samples was evaluated based on results of X-ray diffraction and scanning electron microscopy. Using lime and fly ash, the preliminary investigation showed that addition of 5 % lime and 10 % fly ash constitutes the threshold of the treatment agents needed to form ettringite. However, long-term hydration resulted in lowering pH, and disintegration of formed ettringite. To overcome this problem, aluminum was added to the samples and formation of ettringite was monitored over a period of 660 days. Experimental results indicated that on availability of aluminum for reaction, primary and secondary ettringite minerals are formed and precipitated in these samples. Furthermore, the analysis indicated that the formed ettringite minerals remained stable during a hydration period of 660 days.
Proposed Universal Accelerated Test for Alkali-Aggregate Reaction The Concrete Microbar Test
Authors: Grattan-Bellew PE , Cybanski G , Fournier B , Mitchell L 
Published: January 2010

Abstract
The Concrete Microbar Test is modified after a Chinese test, for alkali-carbonate reactive aggregates. The protocol for the test is essentially the same as for ASTM C 1260, Standard Test Method for Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar Bar Method), except for the size of the bars, the grading of the aggregate, the water to cement ratio and the length of the test. The concrete microbars are 40 by 40 by 160 mm. The aggregate is graded to pass a 12.5 mm sieve and be retained on a 4.75 mm sieve. The water to cement ratio is 0.33. The length of the test is 30 days in 1 M sodium hydroxide (NaOH) at 80°C. The test results show that the method is applicable to both alkali-carbonate and alkali-silica reactive aggregates. Moderate correlation was found between the expansions measured in this test at 30 days, and in the concrete prism test (CSA A23.2-14A) at 1 year. Alkali-carbonate reactive aggregates may be distinguished from alkali-silica reactive aggregates in this test by replacing a portion of the portland cement by a supplementary cementing material. The expansions of alkali-silica reactive aggregates, in this test, are significantly reduced by the presence of the supplementary cementing material but expansion of alkali-carbonate reactive aggregates is largely unaffected. It is tentatively suggested that the expansion limit to separate deleteriously alkali silica reactive siliceous limestones from innocuous limestones is 0.140 % at 30 days; the proposed limit for all other aggregates is 0.04 %.
Multi-Scale Microstructural Modeling of Concrete Diffusivity: Identification of Significant Varibles
Authors: Bentz DP , Garboczi EJ , Lagergren ES 
Published: January 2010

Abstract
The ability to predict the expected chloride diffusivity of a concrete based on its mixture proportions and field-curing conditions would be of great benefit both in predicting service life of the concrete and in developing durability-based design codes. Here, a multi-scale microstructural computer model is applied to computing the chloride diffusivities of concretes with various mixture proportions and projected degrees of hydration. A fractional factorial experimental design has been implemented to study the effects in the model of seven major variables: water-to-cement (W/C) ratio, degree of hydration, aggregate volume fraction, coarse aggregate particle size distribution, fine aggregate particle size distribution, interfacial transition zone thickness, and air content. Based on this experimental design, W/C ratio, degree of hydration, and aggregate volume fraction have been identified as the three major variables influencing concrete diffusivity in the model. Following identification of the significant variables, a response surface design has been executed and least squares regression used to develop a simple equation for predicting chloride ion diffusivity in concrete based on these three parameters. This simple equation essentially summarizes the complicated simulations involved in computing the model response. Finally, simulations have been conducted to examine the extent of the surface layer in cast-in-place concrete, where the local aggregate volume fraction near the surface is less than that to be found in the bulk of the concrete.
Evaluation of Rubber-Filled Concrete and Correlation Between Destructive and Nondestructive Testing Results
Authors: Goulias DG , Ali A-H 
Published: January 2010

Abstract
Over recent years significant emphasis has been placed on the use of recycled products in highway and construction materials. Waste materials, such as tire rubber, plastic, and glass may be used with conventional materials either as aggregate replacement or binder enhancement. For portland cement concrete, rubber from granulated tires may be used as an elastic aggregate modifying the brittle failure of concrete and increasing its ability to absorb higher amounts of energy before failure. The replacement of coarse aggregate with rubber particles may significantly compromise strength characteristics of concrete due to the high compressibility of rubber particles, generating localized stresses and bonding problems between the rubber particles and the cement matrix. To the contrary, the use of fine graded rubber as partial replacement of fine aggregates may produce a ductile behavior with large deformations prior to full disintegration of concrete and affect to a lesser degree the strength loss.
An experimental study is being conducted to evaluate the effects of incorporating crumb rubber, very fine tire rubber particles, into Portland cement concrete. The objective of the study is to evaluate the effects of rubber aggregate into portlant cement concrete (PCC) properties. Initially, the rubber content replacing fine aggregates into the concrete mix was investigated by examining the concrete failure characteristics and the amount of energy absorbed during testing. The destructive testing results of the rubber-filled concrete were then coupled with nondestructive testing (NDT) evaluation. The scope of this effort was first to use a well-accepted NDT method for evaluating this specific PCC type, and second, to correlate strength and static elastic modulus to parameters evaluated from the dynamic NDT testing. These relationships may be used for estimating concrete strength and static elastic modulus from NDT results. Nondestructive testing techniques are relatively simple and quick to perform and provide the advantage of using the same samples again and again. NDT techniques are also of particular value in quality control testing.
Changes in ASTM Type II Portland Cement from 1940 to 1994
Authors: Poole TS 
Published: January 2010

Abstract
Historical changes in the specification requirements and properties of ASTM C 150 Type II portland cement are traced from 1940 to 1994. A general trend has been for the strength and heat of hydration properties of Type II cements to converge on the properties of Type I cements. The implications of this trend are discussed.
Influence of Penetrating Chlorides on the Pore Structure of Structural Concrete
Authors: Suryavanshi AK , Swamy RN 
Published: January 2010

Abstract
The present experimental investigation examines the influence of penetrating chlorides on the pore structure of structural concrete. For this purpose, the pore structure of concrete subjected to chloride penetration is compared with that of a similar concrete isolated from chlorides. To achieve the present objective, partially protected concrete slabs were exposed to chlorides for about two years by ponding with an aqueous solution of sodium chloride from the cast face. On completion of the exposure regime, the pore structure of concrete exposed to chlorides was compared with that of the adjacent concrete isolated from chloride intrusion. The concrete subjected to chloride intrusion showed a significant reduction in the number of coarser pores compared to the adjacent concrete isolated from chlorides. Various possibilities, such as degree of carbonation and degree of hydration were examined, step by step, to explain the observed modifications to the pore structure. It is shown that these results strongly suggest that the voluminous chloride-bearing compounds, such as Friedel's salt and calcium chloride, preferentially precipitate in the coarser pores, and thereby decrease the number of coarser pores. Although chloride contamination may thus result in some blocking of the pores in the cover concrete, it is unlikely to enhance the overall durability of the concrete. Further intrusion of chlorides may be hindered for a short time, but it cannot be prevented, and will continue in course of time.
Expansion of Cement Containing Crystalline Magnesia With and Without Fly Ash and Slag
Authors: Liu Z , Tang M , Cui X 
Published: January 2010

Abstract
Crystalline magnesia (periclase) is traditionally considered an undesirable compound in cements since it hydrates slowly at normal temperatures and, hence, causes a delayed expansion. This delayed expansion may be more harmful to the concrete structure than the “early” expansion due to free lime hydration in terms of the soundness of cements. Autoclave expansion tests, such as ASTM C 151, were designed to determine the soundness of cements containing MgO or CaO, or both. On the other hand, the controlled expansion of cements containing magnesia is beneficial, especially to mass concrete. The rate and amount of expansion of cements containing magnesia depend on many factors including the quantity, fineness and calcination temperature of magnesia, cement constituents and strength, presence of mineral admixtures such as fly ash and slag, and storage or service conditions (temperature and moisture). The expansion behavior of portland cements containing magnesia under normal (service) conditions is different from that under the autoclave conditions (high temperature and high pressure). The expansion behavior also differs in the presence of fly ash and slag. The autoclave expansion of portland cement containing magnesia is larger than the expansion at normal temperatures. In the presence of slag, however, cement containing magnesia expands less under the autoclave conditions than under the normal conditions. This implies that one should be cautious when applying the autoclave expansion test to the cement containing slag or other mineral admixtures. The addition of fly ash and slag reduces the expansion of cements containing magnesia with their increasing concentrations. Fly ash is more effective in reducing expansion of cements containing magnesia than slag at the same concentration. These results are summarized in this investigation.
Soundness Characteristics of Portland Cement-Fly Ash Mixtures
Authors: Schlorholtz SM 
Published: January 2010

Abstract
The Materials Analysis and Research Laboratory has been monitoring the soundness of several sources of fly ash since the early 1980's. The soundness tests were generally conducted in accordance with ASTM Test Method C 311 (the autoclave expansion test utilizing 20% fly ash and 80% portland cement, specimens prepared at normal consistency). To date, several thousand tests have been performed on various samples of fly ash that were submitted to the laboratory. Also, additional studies were conducted to investigate the influence of water content (W/CM ratio) and curing regime on the volume stability of portland cement pastes containing a fly ash that exhibited soundness problems.
A Practical Method to Solve Slump Loss Problem in PNS Superplasticized High-Performance Concrete
Authors: Jiang S , Kim B-G , Aïtcin P-C 
Published: January 2010

Abstract
Using the mini-slump and slump tests, three low-alkali Portland cements were found to be incompatible with a PNS superplasticizer in terms of fluidity loss in cement pastes and con-cretes having low W/C ratios (0.30 to 0.35). The addition of a small amount of sodium sulfate appeared to be a practical method to solve the slump loss problem of these superplasticized cement pastes and concretes.
The addition of sodium sulfate between 0.2 to 0.8% (or at a Na2O eq. of 0.10 to 0.35%) significantly reduces the rate of the slump loss and maintains a high slump value over 90 min after mixing of the superplasticized concrete mixes having a W/C ratio of 0.30. Moreover, the addition of sodium sulfate was not found to affect the air content of the fresh concretes. The setting of the concretes are retarded or accelerated by no more than 2 h depending on the amount of sodium sulfate added. Furthermore, the addition of sodium sulfate up to 0.5% to the superplasticized concretes increases not only the 1-day compressive strength but also the 28-day compressive strength. The addition of sodium sulfate over 0.5% was found to increase the 1-day compressive strength but to decrease the 28-day compressive strength.