Express Forecast of Portland Cement Strength Using Conductimetric and Thermogravimetric Analyses

Questions of express (within 15 minutes or 24 hours) instrumental forecast of Portland cement strength by means of conductivity and (or) gravimetric measurements are considered. It is shown that the specific resistivity of the sample of cement-sand mortar of standard composition (1:3, W/C=0.5) or the determination of the degree of hydration of cement stone (W/C=0.3-0.32) for interval losses during thermogravimetric analysis in the period of 24 hours provides fairly reliable results in the range of 40 to 70 MPa for R28 and 12-30 MPa for R3 days during the first 15 minutes. A comparison of the different nature of the forecast methods adequacy for Portland cement durability (for "ion" power and transformation of cement-framework of grains) demonstrates the compatibility of these practices and ensures the convergence of the strength results. The use of these different techniques also provides additional information about a number of important construction and technical characteristics (the period of cement setting in the solution, the number of mineral additives, the content of Ca(OH)2, etc.).