Ceramics-Silikáty 23, (3) 217 - 231 (1979)

Cement clinker of usual chemical composition which has been ground with a grinding aid in the absence of gypsum to a specific surface in excess of 400 m²/kg and processed at a low water to cement ratio with an addition of a plasticizer and a set regulating agent represents a hydraulic cement setting and hardening at temperatures below 0 °C. This hydraulic cement has been given the designation modified rapid-hardening high-strength cement (further on the Czech abbreviation MRVO is used throughout the text). At the optimum combination of the additions, the MRVC can be processed at the following low water to cement ratios: pastes w = 0.20-0.26, mortars w = 0.27-0.33 and concretes w = 0.32-0.37 when using standard technological equipment. The setting and hardening of MRVO was verified in the form of pastes, mortars and concretes in laboratory at temperatures down to -36 °C, and on building sites at temperatures down to -20 °C. Concrete made of MRVO with a specific surface of 720 m2 /kg and exposed continuously to the conditions of an open building site (minimum night-time temperatures of down to -20 °C) developed the following compression strengths: 1-day 10 MPa, 3-day 22 MPa, 7-day 45 MPa and 28-day 58 MPa.