Research On Non-clay Ceramisite And Its Concrete Performance

This subject has analyzed the technologies, the resources, the power consumption and the economy feasibility to produce the non-clay shale ceramsite. It has comprehensively evaluated that non-clay shale ceramsite is suitable for the construction in Beijing city by a large quantity of research experiments and contrast experiments on the properties of various kinds of ceramsites. It has also developed the ceramsite's properties which impacted on the fluidity and stability of the concrete mixture and impacted on the mechanical properties, the volume stability,strength and durability of the hardened concrete. It has also technically analyzed whether the more preferable ceramsite can substitute to the clay or the shale ceramsite by testing the fluidity, stability of the ceramsite concrete mixture and testing the mechanical properties, the volume stability and the durability of the hardened concrete. It has observed the microscopic structure of the ceramsite and the interface region characteristics of the ceramsite concrete and analyzed the interaction mechanism between the light aggregates and the set cement by the SEM test method. The subject has also analyzed whether the optimized non-clay ceramsite can subtitute to the clay and shale ceramsite.The results show that the cost of the fly-ash ceramsite and the sludge ceramsite is comparatively equality,and the coal gangue ceramsite costs the highest energy consumption, and the sludge ceramsite needs the lowest comprehensive energy consumption. The cost of the coal gangue ceramsite is the highest one, and it cost the highest energy-consumption, and the fly-ash ceramsites is the second one, and the sludge ceramsite is the lowest one. Comparing the properties of the ceramsites, the fly ash ceramsite has the smallest bulk density coefficient of variation about 0.05, and it has the best uniformity, best mass stability, and the list particle shape coefficient. The fly-ash ceramsite's water absorption(including the atmospheric pressure water absorption, the water absorption before and after cleaving, the connected ratio and the pressure water absorption ) and the cylindrical compress strength are between the coal gangue and the sludge ceramsite. After comprehensive evaluation, we decide to use the fly-ash ceramsite in the concrete experiments.For the properties of the concrete mixture, the fluidity of the round-type fly ash ceramsite concrete is better than the common type fly ash ceramsite concrete, however, the density delamination degree and the quality delamination degree of the round type fly ash ceramsite concrete is much larger. The more estimated water absorption of the fly ash ceramsite has, the fresh concrete mixture has the larger slump and extension and the smaller of the loss and delamination degree. The best pre-wet time of the fly ash ceramsite is about 24 hours. The best sand ratio of the fly ash ceramsite concrete is 40%. Alone with the particle diameter of the fly ash ceramsite increasing, the concrete compressive strengthen have decreased. Alone with the pre-wet time of the fly ash ceramsite prolonging, compressive strengthen at early age has decreased and the later period compressive strengthen has increased. After 28d, the fly ash ceramsite concrete shrinkage ratio is also comparatively large. The ceramsite has the larger water absorption ratio, the concrete has smaller shrinkage ratio. The frozen resistance the frost-thawing times of the light aggregate concrete are more than 250 times.Considering the micro-properties, the surface of the fly ash ceramsite is comparatively compact, and the average pore diameter is small. However, the inner structure of the fly ash ceramsite is much different from its surface.It has more pores inside than on the surface, and the average pore diameter is larger than the surface. Microscopic structure of the clay ceramsite concrete in the interface region is similar to the fly ash ceramsite concrete's, which formed the"nested"-type integration structure and improved the concrete strength in the interface region.