THE impact of silica-nano-particles (SNP) on the hydration characteristics of composite
cement containing fly ash (FA) and/or fine granulated slag (FGS) was investigated. The
physico-chemical characteristics of different composite-pastes are studied in the presence
of 4mass% SNP and 40% FA and/or FGS with the existence of 1mass% polycarboxylate
superplasticizer (SP). The physicomechanical characteristics are studied by determination
of the water of consistency, setting times (STs), compressive strength (CS), total porosity,
(TP), bulk density (BD), chemically combined water (Wn), free lime (FL) contents and gel/
space ratio (X). The phase composition of the formed hydrates is investigated using XRD,
DTA∕TGA, and SEM techniques. The represented data shown that 4% SNP improved the
hydration process of the composite cement pastes and exhibited superior-compressive strength
than neat-cement without SNP, this is due to nano-sized-particles and higher-efficiency of
good pozzolanic-action of SNP in the comparison with FA and FGS. The composite cement
containing OPC–40%FGS–4%NS in presence of 1%SP possess the highest improvement
of mechanical-properties, hydration-kinetics, and microstructure of hardened cement pastes.
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