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)) m 2 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 C 3 S 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.