| 摘要 |
PROBLEM TO BE SOLVED: To obtain a concrete for surface enameling treatment having excellent heat resistance and dimensional change properties by including a pitch having the softening point within a specific range and the particle diameter within a specified range in at least cements. SOLUTION: This concrete for surface enameling treatment is obtained by compounding a cement such as Portland cement with a pitch having 200-350 deg.C softening point and 100μm to 4 mm grain diameter at 1/(0.05-0.8) volume ratio of the cement/pitch and, as necessary, further compounding a resin emulsion, an air-entraining(AE) admixture, a dispersing agent, a hardening accelerator, a setting retarder and gravel, crushed stone, etc. and water therewith, kneading and hardening the resultant mixture. The pitch is prepared by heat-treating a petroleum-based heavy oil such as a fluid catalytic cracking residual oil, a by-product oil formed when producing ethylene, an atmospheric pressure distillation residual oil or a vacuum distillation residual oil or a coal-based heavy oil such as coal tar or a coal tar pitch in an inert gas stream at 350-500 deg.C under a reduced pressure or in a nitrogen dioxide containing gas stream at 250-400 deg.C in a system containing nitric acid added thereto. |
