Sustainable and Durable Performance of Pozzolanic Additions to Prevent Alkali-Silica Reaction (ASR) Promoted by Aggregates with Different Reaction Rates

Abstract

The increased use of industrial wastes and by-products to produce concretes and blended cements is a lever to achieve carbon neutrality. Furthermore, they could improve their durability. Some pozzolanic additions can minimize the alkali-silica reaction (ASR), which is a well-known deleterious process that occurs between some reactive aggregates and the alkaline pore solution found in mortars and concretes. This work quantifies the efficiency of four pozzolanic materials (natural pozzolan, P, siliceous coal fly ash, V, silica fume, D, and blast-furnace slag, S) assessed by means of compressive strength testing, open porosity, ASR-expansion measurements, and SEM microscopy. Accelerated expansion tests were performed in mortar bars with a cement/sand ratio of 1/2.25 and a water/cement ratio of 0.47, two reactive aggregates and a non-reactive one. The major contributions of this paper are: (i) The more aggregate reactivity is, the higher ASR mitigation level was found when additions were added and (ii) The best additions for ASR inhibition are silica fume and fly ash.

Durability of Blended Cements Made with Reactive Aggregates

“…The expansion provoked by the alkali–silica reaction (ASR) appears to depend on the basicity of the binder matrix, with a higher basicity leading to a greater level of expansion. Accordingly, the use of the four pozzolanic materials in the Portland cement lowers the lime content and mainly increases the SiO 2 content, and sometimes the Al 2 O 3 and Fe 2 O 3 contents of the final pozzolanic cement, therefore reducing its basicity [ 26 ]. This fact justifies why pozzolanic additions with a higher CaO content are normally less effective in mitigating ASR expansion in accordance with the results found in the literature [ 27 , 28 ].…”

Effect of the height of reinforced concrete layer on the mechanical properties of functionally graded concrete incorporating fly ash and polypropylene fiber

“…Meanwhile, the compressive strength of FGC incorporating Fa was lower than that of concrete with the single layer (100N) and FGC without Fa at the early ages (3 and 7 days), regardless of PP fiber addition. It is due to the dilution effect and slow reactivity of Fa [12,30]. However, the compressive strength of FGC specimens containing only Fa (50FA/50FA) was almost the same as that of normal concrete with the single layer (100N) at 28 days.…”

“…The target slump and compressive strength at 28 days were 8 ± 2 cm and 70 MPa, respectively. According to the previous studies [4,12,13], Fa was used to replace OPC at 20% by mass of cementitious materials in the concrete mixtures. Moreover, PP fiber with a content of 0.3% by volume of concrete which was the optimal content for structural and economic aspects according to previous research [5,6] was used.…”

“…However, the compressive strength of FGC specimens containing only Fa (50FA/50FA) was almost the same as that of normal concrete with the single layer (100N) at 28 days. The reason is probably due to the pozzolanic reaction of Fa, which generated the additional C-S-H and C-A-S-H [12,30] and enhanced the compressive strength of FGC. On the other hand, the inclusion of PP fiber was found to positively increase the compressive Figure 13.…”

“…[5]. Based on the recommendation of previous studies [4,5,[10][11][12][13], the replacement of OPC with Fa at 20% by mass of cementitious materials and the addition of polypropylene fiber at 0.3% by volume of concrete were carried out in this research to reduce the use of OPC as well as improve the flexural performance of FGC. On the other hand, an important aspect of FGC is the thickness (height) of double-layer concrete which was previously mentioned by Torelli et al [10] and Chan et al [6].…”