Rheological and mechanical properties of microfine-cement-based grouts mixed with microfine fly ash, colloidal nanosilica and superplasticizer

To ensure desirable fluidity, less leaching and mechanical properties of grouts in geotechnical engineering, a microfine-cement-based grout mixed with microfine fly ash (MFA), colloidal nanosilica (NS) and superplasticizer (SP) was designed. In this paper, the rheological and mechanical properties of grouts with different additives were investigated. The results show that all microfine-cement-based grouts have satisfactory apparent viscosity, behave as Bingham fluids, are stable for water/solid (W/S) ratio = 1.2. The incorporation of MFA and SP each improve the fluidity and spreading ability of fresh grouts, while prolonging the setting time. The addition of NS has negative effects on fluidity and shrinkage property of fresh grouts, nevertheless, it has positive effects on shortening setting time, enhancing stability and mechanical properties.