Abstract
abstract: Alkali-silica reaction (ASR) is one of the most harmful distress mechanisms that affects the durability of concrete worldwide. Yet, it has been found that ASR-induced expansion and distress may be prevented by the appropriate use of supplementary cementing materials (SCMs). Recent studies suggest that rice husk ash (RHA), a by-product of the rice production, may present promising performances as a pozzolanic material and to enhance the durability of blended mixtures. There are many controversial studies regarding the use of RHA and how its properties directly affect the performance and durability of concretes and mortars. The present study aims to evaluate the influence of the RHA on ASR through the accelerated mortar bar test (AMBT), X-Rays Diffraction (XRD), Thermogravimetric Analysis (TG), Mercury Intrusion Porosimetry (MIP) and Scanning Electron Microscopy (SEM). To validate the obtained data, the results were compared with mortars made of a well-known SCM (silica fume) which has distinguished behaviour against ASR. The results indicate that, besides the silica fume mortars have showed better results, the use of RHA suggests promising results to mitigate the ASR, yet, further analysis on concrete prims test should be carried out to fully validate the use of RHA to enhance the durability of the concrete. The RHA finesses and its particle size were the most important properties in the SCM performance.
Highlights
Concrete is the most common construction material used in critical infrastructure worldwide
4 CONCLUSIONS The main objective of this research was to evaluate the influence of the rice husk ash (RHA) to suppress Alkali-silica reaction (ASR) in mortar bar specimens comparing its behaviour with well-known supplementary cementing materials (SCMs) which has distinguished performance against ASR
Mortar bars made of silica fume demonstrated the best results, showing considerable reduction in damages and decelerating ASR kinetics
Summary
Concrete is the most common construction material used in critical infrastructure worldwide. Alkali-silica reaction (ASR) is one of the most harmful distress mechanisms that affects the durability of concrete worldwide. It is comprised of a chemical reaction between “unstable” silica mineral forms (from fine or coarse aggregates) and alkali hydroxides (e.g. Na+, K+ and OH-) dissolved within the concrete pore solution [2]. It generates a secondary product, the ASR-gel, which has swelling properties and may generate internal stresses and cracking in the concrete [2]–[4]. It has been found that ASR-induced expansion and distress may be prevented by the appropriate use of supplementary cementing materials (SCMs) [6]
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