Comparison of ASR Mitigation Methodologies

Abstract

This study evaluates the dosages of Class F fly ash, lithium nitrate and their combinations to suppress the excessive expansion caused by alkali-silica reactivity (ASR). In order to serve the proposed objective, the mortar bar specimens were prepared from (1) four dosages of Class F fly ash, such as 15, 20, 25 and 30 % as a partial replacement of Portland cement, (2) up to six dosages of lithium nitrate, such as lithium-to-alkali molar ratios of 0.59, 0.74, 0.89, 1.04, 1.19 and 1.33, and (3) the combination of lithium salt (lithium-to-alkali molar ratio of 0.74) and two dosages of Class F fly ash (15 and 20 % as a partial replacement of Portland cement). Percent contribution to ASR-induced expansion due to the fly ash or lithium content, test duration and their interaction was also evaluated. The results showed that the ASR-induced expansion decreased with an increase in the admixtures in the mortar bar. However, the specimens made with the both Class F fly ash and lithium salt produced more effective mitigation approach when compared to those prepared with fly ash or lithium salt alone. The ASR-induced expansions of fly ash or lithium bearing mortar bars by the proposed models generated a good correlation with those obtained by the experimental procedures.

Quantitative analysis of the evolution of ASR products and crack networks in the context of the concrete mesostructure

“…While different approaches have been proposed to reduce expansion and damage due to ASR (e.g. [5][6][7]), effective mitigation or suppression approaches have not yet been established. This is partly due to the lack of a comprehensive understanding of the underlying mechanisms of ASR cracking.…”

Micro and Nano Engineered High Volume Ultrafine Fly Ash Cement Composite with and without Additives

“…Therefore, using fly ash as a cement replacement material provides dual benefit (i) it helps in increasing the use of this industrial by product and (ii) it assists in cutting down the emissions associated with the cement production. Moreover, it not only enhances the properties of fresh concrete like workability (Sata et al 2007;Liu 2010) but also improves its mechanical and durability properties such as; greater long term strength (Hansen 1990;Sivasundaram et al 1990), lower shrinkage (Atis 2003;Nakarai and Ishida 2008), lower water absorption (Malhotra and Mehta 2002;Ş ahmaran et al 2009), reduction in chloride permeability (Nagataki and Ohga 1992; Dinakar et al 2008), increased resistance to sulphate attack (Structure et al 1986;Turanli et al 2005), low heat of hydration (Turanli et al 2005;Kasai et al 1983) and reduction in alkali aggregate reactivity (Turanli et al 2005;Pepper and Mather 1959;Islam 2014). Although fly ash has many advantages when used as a cement replacement material, it has one major disadvantage of low reactivity (Liu 2010;Ş ahmaran et al 2009).…”