Study On High Performance Concrete Of Hill Sand

It has been almost 40 years since the use of hill sand in civil engineering in Guizhou spontaneously in the end of 1950s. Used as an aggregate in concrete, hill sand is a material of promise and economic which can be obtained locally. With the development of basic construction in our country, People pay more and more attention to the serious short of sand. The problem of transportation and time can be solved by producing hill sand in regions with abundant resource which can also lower cost and save river sand. High performance concrete has been playing an important role in the advancement of building industry. But it has limitations such as inconsistency between strength and theological properties, the problem of volume invariability and the properties of resistance of sulfate erosion especially for concrete in excess of 70MPa.It is an difficulty for both the concrete industry and building industry to ensure the concrete in excess of 70MPa with good theological behavior, ease of transport, volume soundness and durability after hardened. Hill sand can be used in producing high performance concrete of hill sand based on the research of high strength concrete of hill sand, hydro-concrete of hill sand and the usage of fly ash.The research is to develop a new material----high performance concrete of hill sand on the basis of practice of high strength concrete of hill sand and knowledge of ultra-fine trass additive by using concrete material in Guizhou and mixing fly ash. The research result shows that the flowability, moldability, cohesiveness of high performance concrete of hill sand are significant by comparison with ordinary concrete on mechanical properties, long term properties, and durability. Motar flowability decreases with the increase of single-mixed active additive. The flowability can be largely improved by double mixing of active additive and super plasticizer NF. This is because not only the active additive has filling effect but also the dispersing effect induced by surface action between additive and super plasticizer NF. And the optimal content of materials are: super plasticizer NF≥0.8%, fly ash 20%, PS 20~30%,zeolite powder≤20%,SF 5~8%; The negative influence of hill sand powder should be avoided by controlling of powder content and the use of active additive and super...