RAPID HARDENING COMPOUND CEMENTITIOUS MATERIAL

摘要

The compound system of ordinary Portland cement and sulpho-aluminate cement shows some special properties which are imperative for rush repair work. The setting time of the compound system is adjustable from 10 minutes to hours by the combined use of accelerator and retarder simultaneously, and the time between initial and final setting is very short. The strength develops rapidly after setting, compressive strength at 30 minutes can reach as high as 8~10 MPa. The final strength at 28 days is over 50 MPa, and continue develops afterwards. The influences of temperature, water solid ratio and other chemical admixtures on the properties the compound cementitious material was also examined and discussed. The strength and free expansion rate of concrete made of the cementitious material were measured. The mortar made from the cementitious material showed good corrosion resistance to erosive solution and good frost resistance. By means of XRD analysis and porosity measurement, the mechanism of high early strength was discussed. The compound cementitious material has been used in several rush repair engineering.