Studies On Micro-aggregate Effects And Morphological Effects Of Mineral Admixture

Because of mineral admixture's unique micro-aggregate effects, morphological effects and chemical effects, it can improve many properties of concrete and effectively reduce production costs, so mineral admixture play an irreplaceable role in Concrete technique.Recent, with the increasing popularity of ready-mixed concrete, fly ash, slag powder and other mineral admixtures are very popular, but because of regional differences, slag powder, fly ash and other mineral admixture resources are unevenly distributed, Forâ… level fly ash, S95 level of slag powder and other high-quality mineral admixture in the amount of larger cities are in short supply, leading to a variety of finely ground waste becoming "fly ash " admixture of raw materials into ready-mixed concrete market.In the national standards of mineral admixtures, fly ash requires only 45um sieve requirements, and slag powder requires surface area is greater than 350 m2/kg, these indicators can not effectively guide mineral admixture play the role of micro-aggregate effects and morphological effects in concrete, making the concrete densify. So the article systematly study micro-aggregate effects and morphological effects, provide theoretical basis guiding for research high-quality mineral admixture.In the study of micro-aggregate effects of mineral admixture, there has a good correlation between distribution index of mineral admixture and loose packing density of Cementitious materials, distribution index smaller, more close to the Fuller curve of particle distribution , the greater the packing density, distribution index can reflect the degree of the packing density of particles; limestone replace 30% cement,take the test adaptability of cement with superplasticizer,cement paste rheology and concrete workability. The results showed that: test of adaptability of cement with superplasticizer can effectively evaluate difference of micro-aggregate effects, there has a good correlation between saturation point of cement and the surface area of cement, the Marsh time link with the distribution index;Addition of limestone particles with low specific surface area (in the 400 m2/kg) and the wide distribution could reduce the amount of superplasticizer, when we want to produce flow properties of concrete, we can be mixed with high surface area (greater than 1000 m2/kg) and wide particle size distribution of limestone powder to adjust liquidity, increase the degree of expansion.In the study of morphological effects of mineral admixture, by comparing similar particle size distribution of limestone powder and fly ash as mineral admixture on test of adaptability of cement with superplasticizer,mortar fluidity and concrete workability. The results showed that: Using of test of mortar fluidity and concrete workability can can effectively evaluate difference of morphological effects,in the case of similar micro-aggregate effects, morphological effects greater impact expansion degree of concrete,the W/B greater, morphological effects on expansion degree of concrete greater;contrast of different fineness of original fly ash and grinding fly ash, the results show that: the results show that: the original coarse fly ash particles after grinding(surface area of grinding fly ash<400 m~2/kg), a part of original large spherical bead has been destroyed,while the body release more small spherical bead,improving micro-aggregate effects and morphological effects of mineral admixture.