Research And Application Of Non-steam Curing Reactive Powder Concrete

Reactive Powder Concrete (RPC)is a new kind of structural material with high performance of mechanics and durability, and has been widely used in engineering practice on domestic and overseas. The weight of building 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.This research is based on National"No.11 five years plan"technology supporting object (2006BAJ02B0504). Non-steam curing RPC is successfully mixed by using high activity superfine powder (PL powder) developed by us substitute silicon fume, natural sand substitute standard sand and standard curing substitute steam curing. This RPC is conducive to reduce the costs and promote the applications in municipal engineering. The mechanical performance, durability and shrinkage of concrete have been studied. The use of non-steam curing RPC to make high strength grate has been a patent application (Name: Non-steam curing reactive powder concrete, number: 200910310966.4).The influences of four admixtures are analyzed, results indicate as follows: PL power is more suitable for preparation of RPC. Non-steam curing reactive powder concrete is prepared by standard curing system using PL powder, 52.5 cement, natural sand, steel fibers and superplasticizer, and some other materials. The compressive and flexural strength at 28 days of RPC are up to 120.7 MPa and 29.3 MPa, and the cost is only the half of common RPC, to promote the development and application of RPC.Strength of non-steam RPC has certain rules. Strength increased with the increase of PL power content, and when content is higher than 15% the increase of strength becomes more slowly; there has a saturation point of sand binding material ratio, when sand binding material ratio is lower than 1.2, strength increased with the increase of sand binding material ratio and decreased when sand binding material ratio higher than 1.2; and strength increased with the increasing of either superplasticizer or steel fiber content.Non-steam curing RPC performs well in durability and shrinkage. The ionic diffusion coefficient is less than half of C80 concrete and is one order of magnitude lower than C40 concrete. At 28 days, the shrinkage of the RPC is 60% of C40 concrete and the depth of carbonation is zero.The strength of high-strength well grate used of non-steam curing reactive powder concrete more than used of ordinary concrete, to meet demands for heavy grate well in Beijing standard; the successful development of high-strength well grate solved the problem of stolen cast iron grate, and the shortcomings of well grate used of ordinary concrete, resulting in significant economic and social benefits.Experiments show that the strength of non-steam curing RPC grates is double times than common concrete grates, and can meet requirements of Beijing local standard for heavy grate well. The application of this RPC grates is the key to avoid being stolen of cast iron grates and disadvantages of common grates, that generated remarkable social and economic returns.