Effects of silica fume and aggregate size on the brittleness of concrete

Diversifying two-stage mixing approach (TSMA) for recycled aggregate concrete: TSMAs and TSMAsc

“…Concrete is of a three-phase system, comprising coarse aggregate, mortar matrix with fine aggregate, and Interfacial Transition Zone (ITZ) between coarse aggregate and the mortar matrix [18][19][20]. In concrete, ITZ between cement paste and aggregate plays a critical role.…”

Failure characteristics of self-compacting concretes made with recycled aggregates

“…Although micro-fine materials like SF make the ITZ denser and structurally stronger, the existence of two ITZs for RAs mixes makes a weaker attach for RAs and hence reduces the G F of RCAs [24]. Tas ßdemir et al [49] and others [47,52,53] believed that the decrement of G F due to the inclusion of SF was related to the cement paste-aggregate interfacial bond and the microstructural heterogeneity in the concrete. In concretes without SF, the pasteaggregate interface had a large amount of calcium hydroxide and also much fewer dense calcium silicate hydrate.…”

“…Consequently, the brittleness index was substantially high. Without SF, however, the cracks usually develop around the coarse aggregate resulting in a more tortuous fracture path [47,49,52,53].…”

Cement-matrix structural nanocomposites

“…The most well-known effect of silica fume is the increase in strength [20,21,23,, including the compressive strength [20,23,, tensile strength [23,63,66,74,75,85] and flexural strength [62,69,75,86,87]. The strengthening is due to the pozzolanic activity of silica fume causing improved strength of the cement paste [39,82], the increased density of mortar or concrete resulting from the fineness of silica fume and the consequent efficient reaction to form hydration products, which fill the capillaries between cement and aggregate [53], the refined pore structure [58,79] and the microfiller effect of silica fume [79,80].…”