Rheology and microstructure development of hydrating tricalcium silicate - implications for additive manufacturing in construction

Dielectric RheoSANS measurements are conducted on hydrating triclinic and monoclinic tricalcium silicate pastes with and without a sucrose admixture to simultaneously probe the changing microstructure by small angle neutron scattering (SANS), rheology, and electrical conductivity. The average total surface area of nanoscale calcium silicate hydrate (C-S-H), determined from fractal models fitted to SANS data, at the setting time is estimated to be (17.1(56)) m2 cm−3, independent of C-S-H polymorph or retardation of the hydration reactions. The growth rate of C-S-H with respect to the degree of hydration of the triclinic tricalcium phase is approximately 48 % less than the monoclinic tricalcium silicate phase, a result that may be attributed to the increased number of fine grains in the monoclinic C3S paste. Developing an understanding between the microstructural changes of cement paste and engineering material properties is a critical first step toward engineering cement phase compositions.