METHOD FOR MANUFACTURING RAPID-HARDENING AGENT AND CONCRETE PRODUCT

摘要

To provide a rapid-hardening additive and a method for producing a concrete product, whereby an initial strength is obtainable even when a mixed cement is used. The rapid-hardening additive comprises a heat-treated product which is obtained by heat-treating a mixture of a CaO raw material, a CaSO 4 raw material and at least one raw material selected from the group consisting of an Al 2 O 3 raw material, a Fe 2 O 3 raw material and a SiO 2 raw material and which contains from 10 to 70 parts by mass of free lime, from 10 to 50 parts by mass of a hydraulic compound and from 10 to 60 parts by mass of an anhydrous gypsum, per 100 parts by mass in total of the free lime, the hydraulic compound and the anhydrous gypsum. The method for producing a concrete product comprises incorporating from 2 to 15 parts by mass of the above rapid-hardening additive in 100 parts by mass of a cement composition comprising cement and the rapid-hardening additive, and adjusting the stream curing temperature from casting to removal of formwork to be at most 70°C and the maturity from casting to removal of formwork to be from 210 to 320°C·hr.