The temperature effect on portland cement strength

The paper presents the results of predictive modelling of the curing mechanism of the type CEM I 42.5B Portland cement using the VCCTL tool. The cement curing is studied during 28 days within the 0–99 оС temperature range. It is shown that the degree of Portland cement hydration is ~0.55 at 10 оС, and with the temperature increase the hydration process substantially intensifies. The hydration degree of 0.75 is achieved after 50 hours at a temperature over 90 оС. The VCCTL modelling is used to determine the quantitative content of the initial minerals and the main reaction products calcium silicate hydrate comprising C-S-H and portlandite (CH). Their total amount significantly grows during the indicated time period. In Portland cement, the amount of clinker minerals decreases, whereas the fraction of hydrated cement comprising C-S-H and CH achieves 0.70 of the solid phase and pore space. The temperature has a great effect on these processes. The pore space reduces with the increasing time and temperature. It is found that the effective elastic moduli of Portland cement rapidly grow during 400 hours and achieve the following values: 16.79 MPa for the bulk modulus, 8.90 MPa for the shear modulus and 22.69 MPa for Young’s modulus. The equivalence of the VCCTL modelling of cement curing is examined by a search for the correlation between the experimental values of the yield stress at 20, 40, 50 and 70 оС and Young’s modulus. With a high degree of reliability, this correlation matches the cubic function which is in agreement with the literature data