Effects of nanosilica on supersulfated cements of different clinker-activation degree

Abstract

Alkalinity fluctuations in supersulfated cement (SSC) significantly affect its compressive strength, limiting its utilization, but there is a lack of systematic study and compensation techniques. The effects of clinker content (0.5 wt%, 1 wt%, 3 wt%, 5%, i.e., C0.5, C1, C3 and C5) and nanosilica (NS) addition on the performance of SSCs were investigated. Experimental results showed that 1 wt% NS effectively reduced the sensitivity of clinker content of SSC (the compressive strength of SSC did not change when clinker dosage changed from 0.5 wt% to 1 wt%). However, NS retards the early hydration caused by the hindering of ettringite precipitation (most apparent in the low clinker samples C0.5 and C1). The addition of NS improved the early and later age compressive strength and slag reaction degree, reduced the porosity, and refined the pore structure in the high clinker SSCs (C3 and C5) compared to the low clinker group (C0.5 and C1).