Potential Alkali-silica Reactivity Research Articles

Pozzolanic Reactivity of High-Alkali Supplementary Cementitious Materials and Its Impact on Mitigation of Alkali-Silica Reaction

The growing scarcity of conventional supplementary cementitious materials (SCMs) such as Class F, Class C fly ashes, and slag has necessitated exploring alternative SCMs previously considered suboptimal. In particular, high-alkali SCMs are often avoided because of the potential concern that their alkali content could release into the concrete pore solution, thus exacerbating the potential for alkali-silica reaction (ASR). However, preliminary research indicates that not all high-alkali SCMs are deleterious, and some can effectively suppress the ASR expansive reaction when used in sufficient dosage levels. This study evaluates the feasibility of using high-alkali SCMs, such as high-alkali natural pozzolans and reclaimed fly ashes, focusing on their pozzolanic reactivity and the correlation between the reactivity and their ASR mitigation performance. The pozzolanic reactivity of the SCMs was evaluated by the R3 test per ASTM C1897 and strength activity index test per ASTM C311. Thermogravimetric analysis was used to determine the calcium hydroxide consumption by the SCMs. ASR mitigation performance of SCMs was evaluated in accordance with American Association of State Highway and Transportation Officials (AASHTO) T380 miniature concrete prism test. Additionally, pore solution expression and analysis of paste specimens were conducted to determine the correlation between the total alkali and the released alkali levels into the pore solution. Based on the results of this study, all SCMs indicated high pozzolanic reactivity; however, individual performance varied by test method. Ultimately, the high-alkali SCMs, particularly natural pozzolans, did not appear to release any significant levels of alkalis into the pore solution readily and, therefore, show potential for ASR mitigation when used in sufficient dosage levels.

Utilizing Crushed Waste Glass as a Sustainable Replacement for Fine Aggregate in Concrete

Concrete, a vital material in modern construction, combines strength, durability, and fire resistance. However, the conventional use of river sand in concrete is ecologically concerning due to its scarcity and environmental impact. To address this, waste glass is explored as a sustainable replacement for fine aggregate. This study investigates the effects of crushed waste glass on concrete workability, water absorption, compressive strength, and flexural strength. Different glass replacement levels (0%, 10%, 20%, and 30%) and curing periods were considered. The research aims to optimize glass content, evaluate its impact on concrete properties, and compare its environmental effects with traditional methods. The results indicate that waste glass improves workability and reduces water absorption. Compressive and flexural strengths initially increase with glass content but decrease at higher levels, due to potential alkali-silica reaction. The study concludes that waste glass can be effectively utilized in concrete to enhance sustainability and resource conservation. Further research is recommended to explore specific applications and long-term effects.

Petrographic Evaluation of Aggregate from Igneous Rocks: Alkali–Silica Reaction Potential

A thorough petrographic evaluation of aggregates from igneous rocks in terms of their alkali–silica reaction (ASR) potential is crucial in ensuring the durability and long-term performance of concrete structures, especially those where access to additional alkalis is possible, such as from de-icing agents. The aim of the research was to assess the potential reactivity of aggregates from igneous rocks, as only such aggregates are used for concrete airport pavements in Poland. Petrographic analysis was conducted to identify the reactive minerals in the aggregate, and it was extended by quantitative image analysis. The strained, microcrystalline and cryptocrystalline quartz were found to be reactive components but significantly differed in content. It was found that aggregates from igneous rocks were characterized by different susceptibility to ASR and that methods to mitigate the occurrence of ASR should be considered to be used in airfield concrete. A relationship between the content of analyzed reactive minerals and the expansion of mortar bars in AMBT, as well as of the concrete prism in the CPT method, was revealed.

Assessment of the thermodynamics of Na,K-shlykovite as potential alkali-silica reaction products in the (Na,K)2O-CaO–SiO2-H2O system

The thermodynamic description of the alkali-silica reaction is incomplete, due to the lack of thermodynamic data for the alkali-silica reaction products. Here, we estimate the temperature-dependent thermodynamic properties of Na- or K-shlykovite phases which are found to form during alkali-silica reaction in concrete. The thermodynamic properties are then used to produce a series of binary phase diagrams considering different concentrations of alkalis. The results show that these two products start to form at 0.01 mol/kg of alkalis in the CaO–SiO2 binary phase diagrams. Both Na- and K-shlykovite can co-exist with C-S-H at an increased concentration of CaO, consistent with findings that these alkali-silica reaction products may form in real cement systems. However, there is a maximum alkali concentration in the binary phase diagram beyond which shlykovite cannot form, due to limited calcium solubility. This work can help understand and improve alkali-silica testing protocols proposed in standards.

Geological and Geotechnical Assessment of Aggregates Used in Nagar Parker District Tharparkar Sindh Pakistan

Abstract This study aims to determine the geology of granite and evaluate the engineering properties of the samples to make recommendations for the construction industry. The study area is situated in the Nagar Parker complex in Pakistan, which is located in the extreme south-east of the Thar District and the desert of the Sindh Province, near the Run of Kutch (240° 15′–35 30′ N, 70° 40′–58 07′ E), and it covers ca. 500–1,000 km2. In this region, several Quaternary deposits, subordinate and dispersed Jurassic–Tertiary sandstones and clays are overlying the Nagar Igneous Complex basement. According to international standards, there are various possible aggregate sources. However, only a few of them have been reviewed for suitability reasons. Six quarries in Nagar Parker, Pakistan, were selected for evaluation as coarse aggregate in concrete construction and civil engineering works in this research. Although the aggregates from the six quarries are specified and already widely used in the Sindh Province, there is a lack of studies on their geological properties. The results of the presented research revealed that samples from Dhedvero, Karai, Nagarparkar, Mokrio, Dinsi and Wadlai meet all of the international standard requirements for aggregates. Geotechnical, petrographic and geochemistry laboratory tests were conducted in this research and included bulk density, water absorption, specific gravity test, index of flakiness and elongation, soundness aggregate test, crushing value aggregate, impact value aggregate and abrasion value of Los Angeles. Furthermore, chemical alkali-silica reaction potential test and petrographic examination were tested. As a result, we evaluated the properties of granite, which is a crystalline igneous rock with a visibly crystalline structure and texture, made up of feldspar, i.e., potash feldspar and oligoclase. The evaluated minerals are compatible with the standards of civil engineering works and can be used as a concrete aggregate. The evaluated three types of minerals included Dhedvero simple intrusion, Nagar pink granite and grey granite.

ASR potential of alkali-activated soda-lime glass powder in the absence of calcium sources

This study aims to investigate the reaction products of alkali-activated soda-lime glass powder (SLGP) in the presence of calcium sources. To that end, SLGP, blast furnace slag (BFS), and their mixtures were activated using a solution mixed with sodium silicate and sodium hydroxide. To demonstrate their macroscopic behaviors, such as strength development and swelling capacity, hardened synthetics were analyzed using mercury intrusion porosimetry, X-ray diffraction, thermogravimetry, Fourier-transform infrared spectroscopy, scanning electron microscopy, electron dispersive spectroscopy, and nuclear magnetic resonance. The results show that the activation of SLGP with BFS significantly reduced the compressive strength of the synthetics and formed alkali–calcium-silicate hydrates (N-(C)–S–H gels) as binding substances, which had morphological and chemical similarities to swellable alkali–silica reaction (ASR) gels. However, a combination with the BFS transformed the SLGP-products into cementitious C-(N)-A-S-H gels and mitigated not only strength loss but also the swelling phenomena. Based on these results, incorporating SLGP within 50% of the BFS-based synthetics is recommended.

Laboratory investigation of CDG soil as source of fine aggregates for Portland cement concrete

Completely decomposed granite (CDG) soil is a typical and abundant in-situ weathered soil on the ground around the world. This paper investigates the possibility of CDG soil as fine aggregates for production of Portland cement concrete. It first develops a washing and sieving method to separate the CDG soil into its constitutional particles including gravel, sand, silt, and clay. It further examines the properties of the CDG sand using Hong Kong and other standards of fine aggregates for concrete. The first type of the property is the geometrical property including the size gradation, stereomicroscope observation, SEM observation, and shape statistical analysis of the sand particles. The second type is the physical property including magnesium sulphate soundness, compacting bulk density, relative density, and water absorption. The third type is its chemical property including chemical elements, acid-soluble chloride content, water-soluble chloride content, acid-soluble sulphate content, total sulphur content, and presence of humus. The fourth type is the mechanical property including drying shrinkage, effect of organic substances, and alkali silica reaction potential. These test results show that all the properties of the CDG sand well meet the standard requirements and can be used as fine aggregates in Portland concrete.

Application potential of granite cutting waste and tunnel excavation rock as fine aggregates in cement-based materials based on surface characteristics

To alleviate the shortage of river sand (RS) and recycle abandoned resources, two recycled manufactured sands (RMSs) produced from tunnel excavation rock (tuff manufactured sand, TS) and granite cutting waste (granite manufactured sand, GS) are studied and compared with standard sand (SS) and RS. The aim is to identify the application potential of the two RMSs in cement-based materials. This is done by analyzing their influences on the mortar properties based on their surface characteristics and establishing a correlation between the surface characteristics of RMS and mortar properties. For the parent rock, petrographic analysis is performed and the uniaxial compressive strength is measured. For sand, the physical properties are evaluated and X-ray diffraction is used for analyzing the chemical composition. Digital image processing, nitrogen adsorption, and X-ray computed tomography are employed to determine the surface characteristics of sand particles. For the mortar, the fluidity, mechanical strength, water absorption, early total shrinkage, and accelerated expansion ratio are measured. The microstructure of the mortar interface transition zone is examined. Mercury intrusion porosimetry and thermogravimetric analysis are conducted to study the internal mechanism. The results indicate that compared with SS, the two RMSs reduce the fluidity of fresh mortar. In addition, TS is beneficial for the flexural, compressive, and tensile strengths of hardened mortar because of its denser internal pore structure and high degree of hydration caused by the properties of sand. The mechanical strength of the GS mortar can reach a similar or slightly higher level than that of the SS mortar. Furthermore, the fluidity and mechanical strength are well correlated with two parameters of sand, namely, roundness and specific surface area. The tensile strain capacity of the RMS-based mortar is superior to those of the SS and RS mortars. However, RMS increases the early total shrinkage. Although the TS mortar has the highest tensile strain capacity, it also has the largest early total shrinkage among the four mortar mixtures. Comparing the escalations in tensile strain capacity and early total shrinkage, the TS increases the risk of shrinkage cracking in the early stages. The effect of GS on the mortar tensile strain capacity is slightly greater than that on the early total shrinkage; thus, there is no significant influence on the risk of early shrinkage cracking in the GS mortar. In the accelerated expansion test, the TS shows potential alkali-silica reaction (ASR) risk in accordance with ASTM C1260 , however , the GS indicates no potential for expansion damage. Based on the performance of various sands and mortars, GS has a better application value than TS. As for the TS mortar, it is necessary to consider the shrinkage cracking risk and ASR hazard in practical applications. • Application potential of granite cutting waste and tunnel excavation rock as fine aggregates is analyzed. • The surface characteristics of sands are the focus of the discussion. • Correlations between the surface characteristics of recycled manufactured sands and mortar properties are established. • The risk of early shrinkage cracking of recycled manufactured sand mortar is studied.

Expansion and mechanical properties of high-performance concrete with ASR inhibition measures exposed to alkaline solution at 38℃ for 10 years

Continuous follow-up tests on the expansion and mechanical properties of High-Performance Concrete (HPC) with strength classes C40 to C60 using aggregates with potential alkali activity and bulk mineral admixtures in the range of 0.5 % to 1.9 % equivalent alkali content are carried out for 10 years under the action of a standard alkali solution (1 mol/L) at 38 °C. The mechanical properties and expansion of HPC at long ages with potential Alkali-Silica Reaction (ASR) hazards are investigated. The results show: The expansion of HPC soaked in standard alkali solution at 38℃ for 10 years increases with the increase of the equivalent alkali content and decreases with the increase of the HPC strength grade. The KAMJ mathematical model is used to fit and analyze the 10-year expansion of HPC under ASR suppression, and the linear relationship between the expansion constant and Avrami index of the KAMJ model and the equivalent alkali content has been established. The mechanical properties of HPC immersed in standard alkali solution at 38℃ for 10 years decreased with the increase of the equivalent alkali content; During the 10-year immersion period, the compressive strength and flexural strength of HPC experienced a process of first increasing and then decreasing with the increase of soaking time; The use of air entrainment measures has a significant effect on HPC inhibiting ASR expansion and damage and reducing strength loss; A first-order linear equation between the mechanical properties(compressive strength, flexural strength, split tensile strength, axial compressive strength, elastic modulus) of HPC and the internal ASR damage variables within 10 years of exposure to standard alkaline at 38 °C has been established.

Alkali-silica Reaction Elimination Potential of High-Performance Concrete Containing Glass Powder

This study is mainly concerned with the assumption that glass powder can eliminate the potential alkali-silica reaction in high performance concrete. Glass is often land filled, produced as a secondary raw material or as a by-product of production. Chemical analyses were carried out, and the ecotoxicity of the material was investigated, serving as a basis for testing a potential alkali-silica reaction. High performance concrete (HPC) containing different types of waste powder (secondary raw material from production (SGP), jewelry production (SGJ), container waste glass (CWG), and glass from used photovoltaic panels (GPP)) are tested according to the international standard ASTM C1260 and the Czech technical condition TP 137. Newly designed mixtures are innocuous from the ASR point of view in the most cases, except SGP HPC.

Optimization of Parameters of the New Turner-Fairbank Alkali-Silica Reactivity Susceptibility Test (T-Fast)

Abstract Prevention is an effective strategy to avoid damage caused by the alkali-silica reaction (ASR) in concrete structures. The effectiveness of this strategy heavily depends on the use of reliable accelerated tests to determine if an aggregate used in the concrete has the potential to cause ASR. Recently, a new provisional standard test, AASHTO TP 144-21, Determining the Potential Alkali–Silica Reactivity of Coarse Aggregates (TFHRC-TFAST), has been approved by the American Association of State Highway and Transportation Officials. The test accurately predicted the ASR-induced expansion of aggregates used in more than 50 different mortar and concrete samples, including concrete blocks in outdoor testing facilities and concrete in the field. This manuscript presents the results of the collaborative study among three laboratories conducted as part of an overall effort to standardize the new AASHTO TP 144-21. The objectives of the study were to evaluate the suitability of wavelength dispersive x-ray fluorescence (WDXRF) spectroscopy as the main analytical technique, determine the optimal particle size and effect of moisture on calcium oxide (CaO), and evaluate sample preparation on the results. A total of 18 aggregates were evaluated under the TP 144-21 using 4 different CaO samples and 2 sample preparation protocols. The results indicated that the alkali-silica reactivity of the aggregates can be accurately determined by using WDXRF. Upon exposure to the atmosphere, CaO reacts rapidly with moisture to produce calcium hydroxide [Ca(OH)2]. The particle size distribution and amount of Ca(OH)2 in the CaO influenced the ASR classification of marginal (moderately and slow reactive) and nonreactive aggregates. The researchers obtained optimal results using a reagent grade powder CaO with an average particle size of 4.6 μm and less than 5 % of Ca(OH)2. These conclusions were important to validate and optimize the TP 144-21 protocol before launching a wider interlaboratory study.

Rebar corrosion and ASR durability assessment of fly ash concrete mixes using high contents of fine recycled aggregates

This research assessed the potential alkali silica reaction (ASR) of fine recycled aggregates (FRA) derived from precast concrete slabs using petrographic examination and expansion tests, the effects of incorporating FRA on some chloride related transport properties and the corrosion risk of fly ash blended concretes. Mixes incorporating 20 % fly ash (FA) were produced using water-to-binder ratios of 0.45 and 0.50 and FRA replacements of 0 %, 20 %, 60 % and 100 % to test concrete’s mechanical performance, chloride penetrability and rebar corrosion risk using electrochemical techniques at different ages. FRA presented an ASR expansion 227 % higher than natural aggregates. Using high contents (>60 %) of FRA didn’t increase corrosion risk and a comparable risk to conventional concrete was observed when incorporating FA.

Alkali-reactivity of Pernambuco east shear zone coarse concrete aggregates: An experimental discussion

Being the fifth largest country globally, Brazil has a wide variety of rocks used in concrete production. Due to their mineralogical characteristics, many Brazilian rocks present reactive alkali potential, mainly due to the strong presence of silica and/or silicates in their composition. Alkali silica reaction (ASR) was firstly public in Brazil in 1963 in the Jupiá dam. Since then, several ASR events have been reported, namely in Dam and electric power plants, which represent a concern, mainly due to those infrastructures' social, economic, and environmental impact. Even though the selection of the raw materials should consider the aggregate quality and adequacy for a certain application, it mostly depends on the local availability due to economic reasons. Thus, an effective way to evaluate ASR susceptibility on concrete aggregates and predict or prevent the in situ behaviour of the final concrete product properties is crucial. This is particularly important when aggregates sources are Shear Zones, such as Pernambuco East Shear Zone. International standards suggested evaluating aggregate susceptibility prone to ASR through petrographic analysis of aggregates in addition to expansion tests at mortar and/or concrete levels. Concrete prism tests (CPT) are considered the most reliable method for ASR potentially of concrete aggregates; however, CPT are very time consuming, and results might be available after one year. Thus, Brazilian Association for Standardisation suggested a new accelerated concrete test based on RILEM recommendation AAR-4.1, the NBR 15577-7.This work evaluated the behaviour of the coarse aggregate obtained from ZCPE, to prone ASR among different testing conditions proposed by most widespread international standards, namely, petrographic examination, ASTM C 1260, RILEM AAR-4.1, ASSTHO T 380 and NBR 15577-7. Then results were compared and discussed the applicability of the new national standard NBR 15577-7. According to petrographic examination, the coarse aggregate from Pernambuco East Shear Zone was potentially reactive. Expansion tests at mortar and concrete levels corroborated such results, and coarse aggregate was classified as potentially reactive among all standards followed. Thus, it can be concluded that the new NBR 15577-7 outputs similar results compared to other international standards and seems to be a faster way (20 weeks/140 days) to access the ASR potential of reactive aggregates.

Assessment of Alkali-Silica Reaction Potential in Aggregates from Iran and Australia Using Thin-Section Petrography and Expansion Testing.

The alkali–silica reaction can shorten concrete life due to expansive pressure build-up caused by reaction by-products, resulting in cracking. Understanding the role of the aggregate, as the main reactive component, is essential for understanding the underlying mechanisms of the alkali–silica reaction and thereby reducing, or even preventing, any potential damage. The present study aims to investigate the role of petrographic studies along with accelerated tests in predicting and determining the potential reactivity of aggregates, including granite, rhyodacite, limestone, and dolomite, with different geological characteristics in concrete. This study was performed under accelerated conditions in accordance with the ASTM C1260 and ASTM C1293 test methods. The extent of the alkali–silica reaction was assessed using a range of microanalysis techniques including optical microscopy, scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray powder diffraction. The results showed that a calcium-rich aggregate with only a small quantity of siliceous component but with a higher porosity and water adsorption rate can lead to degradation due to the alkali–silica reaction, while dolomite aggregate, which is commonly considered a reactive aggregate, showed no considerable expansion during the conducted tests. The results also showed that rhyodacite samples, due to their glassy texture, the existence of strained quartz and quartz with undulatory extinction, as well as the presence of weathering minerals, have a higher alkali-reactivity potential than granite samples.

Recycled Untreated Rubber Waste for Controlling the Alkali-Silica Reaction in Concrete.

Recycled rubber waste (RW) is produced at an alarming rate due to the deposition of 1.5 billion scrap tires annually around the globe, which causes serious threats to the environment due to its open land filling issues. This study investigates the potential application of RW in concrete structures for mitigating the alkali–silica reaction (ASR). Various proportions of RW (5%, 10%, 15%, 20%, and 25%) partially replaced the used aggregates. RW was procured from a local rubber recycling unit. Cubes, prisms, and mortar bar specimens were prepared using a mixture design recommended by ASTM C1260 and tested for evaluating the compressive and flexural strengths and expansion in an ASR conducive environment for specimens incorporating RW. It was observed that the compressive and flexural strength decreased for specimens incorporating RW compared to that of the control specimens without RW. For example, an 18% and an 8% decrease in compressive and flexural strengths, respectively, were observed for specimens with 5% of RW by aggregates volume at 28 days. Mortar bar specimens without RW showed an expansion of 0.23% and 0.28% at 14 and 28 days, respectively, indicating the potential ASR reactivity in accordance with ASTM C1260. A decrease in expansion was observed for mixtures incorporating RW. Specimens incorporating 20% of RW by aggregate volume showed expansions of 0.17% at 28 days, within the limit specified by ASTM C1260. Moreover, specimens incorporating RW showed a lower reduction in compressive and flexural strengths under an ASR conducive environment compared to that of the control specimen without RW. Micro-structural analysis also showed significant micro-cracking for specimens without RW due to ASR. However, no surface cracks were observed for specimens incorporating RW. It can be argued that the use of RW in the construction industry assists in reducing the landfill depositing issues with the additional benefit of limiting the ASR expansion.

ASR related service life estimation for concrete pavements

In a 5 years study on behalf of the German federal highway research institute (BASt), 71 pavement concretes from 53 highway sections across Germany were examined among other things regarding their residual potential for an alkali-silica reaction (ASR). An empirical approach could be derived for predicting the remaining service life of the concretes. By using earlier correlation data for the climate simulation concrete prism test (CS-CPT) compared to field performance, a translation of the testing period into service life was possible by using a fitted natural exponential function. In the result, the service life of all the pavement concretes could be estimated, ranging from 11 to 51 years, depending on the ASR potential of the concrete mixes with external alkali supply by NaCl de-icer solution. A first agreement between the prediction and the field performance could be found. Further monitoring is supposed to verify and improve the prediction.

Alkali-silica reaction in volcanic rocks: a worldwide comparative approach

The potential alkali-silica reactivity (ASR) of volcanic aggregates, especially basalts, remains a source of debate in the scientific community. When evaluating the potentially deleterious character of this type of aggregate, different laboratory testing methods may produce contradictory data; this is particularly evident when using the accelerated mortar bar test (AMBT). In order to better understand such discrepancies, this study applied several methods of characterizing potential aggregate alkali reactivity, including the accelerated mortar bar test (AMBT), petrographic characterization, and the concrete prism test (CPT). Moreover, this study assessed volcanic aggregate samples from sites around the world, including the Azores, Brazil, Canada, the Canary and Hawaiian Islands, Iceland, Japan, Mozambique, New Zealand, Norway, and Turkey. The results obtained contribute to accurately assessing the potential alkali reactivity of volcanic aggregates and enhance the understanding of their different behaviours.

Assessment of potential alkali-silica reactivity of aggregates for concrete

The detection of concrete structures affected by Alkali-Silica Reaction (ASR) has increased dramatically over the past couple of decades in Portugal. Due to the complexity and multiplicity of factors involved in ASR together with the variability of the materials used, no International or European standards exist for assessing the aggregates potential alkali-reactivity, and each country must rely on national regulations or specifications. Because of that, in Portugal, LNEC Specification E 415 was prepared in 1993 and LNEC Specification E 461 was introduced in 2004 and revised in 2007. However, due to the scientific developments occurred since then, new revised versions were prepared and will soon be published. Although, LNEC Specifications provide guidance on the identification of potentially alkali-silica reactive aggregates, there are still some knowledge gaps on how to reliably assess the potential reactivity of some minerals present in granites and similar rocks, which are the type of aggregate most used in large concrete structures in Portugal. Therefore, to contribute to the current ongoing discussion on the role of the main components of these rocks on ASR development, this paper presents the methodology that was applied in the evaluation of concrete granitic aggregates used in recently built hydroelectric projects as well as in a dam constructed abroad several decades ago, and in which the deleterious development of ASR was detected 15 years after construction.

Alkali-silica reaction of sanitary ware ceramic wastes utilized as aggregate in ordinary and high-performance mortars

Waste management has been the foremost concern in the last decades. Utilizing sanitary ware ceramic (SWC) wastes in concrete has been found to be beneficial in terms of sustainability and cost in previous studies; however, deleterious alkali-silica reaction (ASR) potential of this waste aggregate, albeit it’s high SiO2 content, has not been taken into account. This study aims to examine ASR potential of SWC wastes as well as the effects of permeability, w/c ratio, and reactive powder content of mixtures on the ASR-induced expansions in detail. Accelerated mortar bar, total and capillary water absorptions, and chloride ion penetration tests were conducted for %20, %40, %60, %80, and %100 replacement ratios at the first part of the study. The SWC aggregate showed ASR-induced expansions in “pessimum proportions”. With a 9-day delay, similar patterns (trends) of ASR expansions were observed in the mixtures with a w/c ratio of 0.3 as compared with those of 0.5 w/c ratio. While the ASR expansions had meaningful relations with the water absorption tests and w/c ratio, there was no noteworthy correlation with the rapid chloride ion penetration test results, since the SWC aggregate effected the properties of pore solution. The effect of the finer grains of the SWC aggregate on ASR was investigated in the second part of the study. For this purpose, the SWC aggregate finer than 250 µm was replaced with same sized limestone aggregate. The results revealed that the finer grains of SWC aggregate were responsible for the reductions observed in the first part of the study not due to “pessimum effect” phenomenon but rather to the pozzolanic activity of the finer grains.

Evaluation of Current ASTM Standards for ASR Prevention When Fine Lightweight Aggregates Are Used

Abstract Previous research has shown that using fine lightweight aggregate (FLWA) can be a promising strategy to mitigate alkali-silica reaction (ASR) in mortar and concrete. However, limited studies focused on assessing current ASTM standards for their applicability in evaluating the efficacy of ASR mitigation using FLWAs. In this study, three commercially used FLWAs (expanded shale, clay, and slate) were investigated in mortar and concrete mixtures with reactive aggregates of different levels of reactivity. ASTM test methods, including ASTM C289-07, Standard Test Method for Potential Alkali-Silica Reactivity of Aggregates (Chemical Method) (Withdrawn 2016); ASTM C1260-14, Standard Test Method for Potential Alkali Reactivity of Aggregates (Mortar-Bar Method) (Superseded); and ASTM C1293-18, Standard Test Method for Determination of Length Change of Concrete due to Alkali-Silica Reaction (Superseded), were completed. Fine normal-weight aggregates were replaced by the FLWA at 25 % and 50 % by volume in the concrete mixtures, and 25 %, 50 %, and 100 % in mortar mixtures. Results showed that ASTM C1260-14 and ASTM C1293-18 can be used to evaluate the mitigation efficacy when pre-wetted FLWAs were used. The ASTM C289-07 test is not a reliable test method to study the reactivity of the FLWAs, but the results can be used to indicate the alkali-consuming ability of the FLWAs. All three FLWAs were effective in reducing ASR-induced expansion in both ASTM C1260-14 and ASTM C1293-18. The investigated FLWAs were especially effective in the concrete when moderately reactive aggregates, as classified by ASTM C1778-14, Standard Guide for Reducing the Risk of Deleterious Alkali-Aggregate Reaction in Concrete (Superseded), were used. For concrete with a highly reactive aggregate or very highly reactive aggregate, other mitigation strategies may need to be combined with FLWAs to effectively mitigate ASR.