Investigation On Preparation, Characteristic And Application Of Machine-crushed Mountain Sand

With the development of fundamental construction and the enhancement of environment protection conscious, the nature river sand (NRS) is in short and the use of machine-crushed mountain sand (MMS) is a trend. In the city of YICHANG(Hubei province), there is a large mount of machine-crushed mountain sand. Hence, how to make full use of such resource in the project is a kind of problem that need to discussed.In this study, according to the production method of MMS in the city of YICHANG, the physic properties, production techniques and its influence to concrete were investigated. The results show that:(1) According to the characteristics of the crack resources, two phase were employed to produce the MMS. Jaw Crusher is used to crush the weathered granite coarsely, and then, the Impact Crusher is used to do fine crushing. Besides, during the process of crushing in Impact Crusher, high-pressure water is used, which not only modify the surface conditions, making the surfaces smooth, but also reduce the content of stone powder and silt.(2) The NRS and MMS was compared in macroscopic and microscopic aspects, and the results show that the mineral component is almost the same, which are quartz, feldspar and isinglass respectively. However, there are obvious difference in the apparent sharp, particle shape, porosity, mix range and the content under 0.075mm. Compared to the sand paste with NRS, the sand paste with MMS contain lower workability and better mechanical property. When adding some super fine sand into MMS, the content of the particles size under 0.6mm can be improved, and the workability and mechanical property can all be enhanced. When the content of super fine sand to MMS is 1:9, the workability and mechanical property of the mixed sand come to the best.(3) Utilizing the MMS to prepare C50 high performance concrete, when the water to binder rate is 0.32, the sand rate is 0.38 and the content of fly ash is 20%, the workability and mechanical property of the concrete come to the best. The saturation method of MMS can improve the workability and mechanical property of concrete, and resolve the problem of extensive of slump loss. When the water content is two times of the content of MMS, the results is best. When the fine powder (≤0.075mm) content of MMS is 7-10%, the properties of C30 concrete come to the best, and When the fine powder (≤0.075mm) content of MMS is 3-5%, the properties of C50 concrete come to the best. In the preparation of low range concrete, the content of fine powder in MMS can be increase to enhance the workability. But, when prepare high range concrete, the content of fine powder in MMS should be controlled rigidly to guarantee the property of concrete. (4) The durability of the concrete with MMS was evaluated. The surface of MMS is coarse and shape is not regular, which result in that the MMS can have great connection with cement and the concrete with MMS have great volume stability compared to that with NRS. The MMS have poor mix range and large content of fine powder, which result in that the concrete with MMS have higher porosity and lower durability compared to that with NRS.