Preparation And Application Performance Study Of Porous Low Thermal Expansion Conefficient Functional Aggregate

The aggregate is an important part of concrete,which is an irreplaceable role. It about 70% to 80% by volume of the concrete, it is often seen as an inert filler.However, because of people realize the exertion of aggregate's performance in concrete, the view that aggregate only as an inert filler has been questioned. The aggregate not only have concrete skeleton role, but also influence the concrete volume deformation. The problem of developing functional aggregate, exploring it's characteristic and mechanism of cement-based materials have been waiting to be solved in our country's construction field. This article according to the Material Design Principles and Preparation Technology of functional aggregate, imparting functional characteristics of the aggregate, preparation the functional aggregate that have low thermal expansion coefficient, internal porous and rough surface.Elaborating the causes that the aggregate have low thermal expansion coefficient, and analysis the Expansion mechanism. Exploring the aggregate's particle characteristics and geometric features influence the performance of cement-based materials. Now the following conclusions:?1? By controlling the content of nickel slag, design five sets of matching. With the increase content of the nickel slag, Magnesia content of the aggregate compotent on the rise. The aggregate's thermal expansion coefficient is reduced. The test temperature was 100?. The Magnesinm content of the aggregate component content of 9.09% compared with 6.16% of the thermal expansion coefficient decreased12.02%. Effect of magnesia component content smaller increase of the apparent density of the sintered aggregate, while the volume shrinkage and compressive strength were decreased.?2? According on a comprehensive performance comparison, determine the firing system and ratio of raw materials. On this basis, exploring CaCO₃, C powder, tire end of three kinds of foam components influence of porous low thermal expansion coefficient function aggregate porosity, apparent density, and other properties. By the tire end system, by the end of the tire system, the function aggregate porosity and water absorption are better than the other two systems, and with the increase of tire end content, the aggregate function to reduce the apparent density, water absorption and porosity increases, the outer mixed content is 8% at the end of the tire than the4% increase of 31.85% porosity. The tire end as foaming component not only produces enough gas, and liquid viscosity suitable for the amount of parcels. Thereby have porous aggregate characteristics.?3? Non-spherical crushing porous aggregate possess more edges than spherical crushing porous aggregate.The splitting tensile strength of more porous aggregate is greater than the aggregate with fewer edges,under the same kind of aggregate the amount of angularity determine with the cement pastes' engagement. It can be seen,more angularity aggregate has a role in promoting for splitting tensile strength of cement-based material.?4? The shape and pore of aggregate have an impact on the dring shrinkage of mortar, with the increase of curing period, the dring shrinkage of the aggregate of spherical crushing function is the smallest, the non spherical comes second, and the river sand is the biggest. When the curing age is 28 days, the dring shrinkage of the functional aggregate and the non spherical crushing functional aggregate is decresed by 19.93% and 7.39%.?5? Taking two ways to equal volume substitution of river sand, one of porous fine aggregate multi gradient; another fine aggregate with different content of steinheilite. Testing coefficient of thermal expansion of mortar. and setting quantitative relationship between thermal expansion coefficient of aggregate and cement mortar.When aggregate in the case of completely replacing river sand, the thermal expansion coefficient of cement mortar reaches the minimum, also the more content of steinheilite, the lower coefficient of thermal expansion of mortar.