Evaluation of alkali-silica reaction in recycled aggregates: The applicability of the mortar bar test

Resistance to the alkali-aggregate reaction of sustainable mortars produced with scheelite tailings in replacing natural sand aggregates

“…Figure 6 shows the image obtained by Scanning Electron Microscopy using backscattered electrons (SEM-BSE), in which it was possible to identify the pores of the samples, the aggregates (Scheelite tailings), and the hydration products of the cement paste, such as calcium hydroxide (C-H), hydrated calcium silicate (C-S-H), identified in the circled regions of the image. From Figure 6 is possible to notice no amorphous alkaline gel formation inside the pores, as observed in other works (Barreto Santos et al, 2021;Munhoz et al, 2021;Rashidian-Dezfouli & Rangaraju, 2021). In some images obtained by mirrored electrons of polished samples, some cracks that could be due to a deleterious expansive process were identified.…”

Internal Alkali Transport in Recycling Concrete and its Impact on Alkali-Silica Reaction

“…However, amongst the challenges of using RA in concrete is the presence of mineral phases prone to develop alkali-silica reaction (ASR), a deleterious physicochemical reaction affecting concrete infrastructure worldwide. It has been shown in past studies that reactive aggregates present in RA can lead to induced expansion and cracking of recycling concrete [8][9][10][11][12][13][14][15][16][17]. Typically, the alkali concentration in both RA and RC is similar in such studies; therefore, it is difficult to assess the role of the alkalis already present in the RA and the alkalis provided by the cement of the newly produced RC on the development of expansion and cracking.…”