Study On Macroscopic Properties And Microscopic Mechanism Of RPC

RPC is a new kind of composite material, which has high mechanical property, durability and environment-protecting property compared with conventional concrete. The producing procedures of RPC are closer to the normal concrete and easier to practice. Therefore, it has promising prospect of application. The weight of buildings is lightened, the span of structures is increased, the durability of structures is improved and the maintaining expense of structures is reduced by using RPC instead of conventional concrete.Based on the previous research results, the compressive strength, bending strength and the resistance to chloride ion penetration of RPC under different curing regimes, blended with different mineral admixture, different aggregate, steel fibers with different aspect ratio are tested. The results are that the compressive strength and flexural strength of RPC are greatly different; different mineral admixtures have different enhanced effect; joining two or more complex is better than only one with mixing ratio and curing system suitable circumstances; the strength and durability of RPC gradually increase with the curing temperature increased.Based on this, the hydration products, hydration speed and hydration degree of RPC were analyzed systematically by X-ray diffraction test with different mixture ratio and curing temperature. The micro-morphology and porosity of hardened RPC paste were investigated with SEM and MIP to illuminate the structure of interfacial zone between paste and aggregate. The results are that not hydrated minerals C3S, C2S content is decreasing, Ca(OH)2 crystal content is also declining with the curing temperature increased, so enhancing the curing temperature increases the degree of hydration of cement. Increasing curing temperature stimulates the activity of mineral admixture, and promotes the secondary hydration reaction, consumes Ca(OH)2 to produce more C-S-H, increases the density of the matrix, optimize the microstructure and reduce the porosity of RPC, reveals the microscopic mechanism of macroscopic mechanical properties and durability of RPC.