| 摘要 |
A method of treating the unset surface of Portland cement concrete to form thereon a hardened surface, that is an integral coating, skin, treatment or mass of high early compressive strength, without substantial shrinkage during setting while exhibiting reduced wet and dry volume changes in the hardened state and prossessing a high degree of impermeability to fluids, abrasion, erosion and chemical resistance and similar characteristics desired in a surface treatment having commercial usefulness in a construction industry. The hardened surface is obtained by dry shaking, that is, sprinkling a dry cementitious composition of alumina cement and gypsum on the unset Portland cement concrete. Additional components, such as viscosity controllers, surface active agents, retarders, accelerators, wet expansion inhibitors, gas generating or gas releasing agents, fly ash, plasticizers, pigments, water retentivity aids, fillers, and aggregates may be utilized to adjust the properties of the composition and impart selective improvement of specific properties.
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