Experimental Study On The Properties Of Desert Sand Concrete With Auxiliary Cementitious Materials

With the development of urbanization needs, environmental friendly new ecological environmental protection material become the essential means to improve the environment, human sustainable development has become a common concern all over the world. China’s peripheral regions such as Ningxia, Inner Mongolia has rich resources of desert sand, reasonable development and utilization of these resources, its application in the field of engineering construction, freshwater, the lower the project cost at the same time, also effectively curb desertification, made great contributions to protect the ecological environment, has profound social significance. This paper made of desert sand completely replace natural sand concrete, in view of the previous studies in the process of desert sand concrete cracking, low compressive strength and poor durability problems, through adding fly ash, mineral powder and ecological fiber, study the three work together to improve the performance of concrete of desert sand, and to explore its effect mechanism. For the production of concrete engineering scope of cuhk using desert sand.(1) Poor through orthogonal test and variance analysis methods 28 d,28 d compressive strength of concrete splitting tensile strength index analysis, and to consider economy, comprehensive above index, determine the optimal desert sand concrete mix proportion is:A1B2C1D2E1, namely the water-binder ratio of 0.46, fly ash and mineral powder to replace rate was 15%, sand rate was 32%, the ecological fibre content is 0.96 kg/m3.(2) 28 d mechanical performance test results show that fly ash and mineral powder on the desert sand concrete compressive strength has a certain degree of improvement, and incorporating ecological fiber can improve the tensile splitting strength of concrete.(3) Shrinkage test show that the contrast group of concrete shrinkage rate is larger than the other two groups of shrinkage rate, and the optimal set of minimum shrinkage of concrete, complete with desert sand production will increase the cracking concrete contraction, mixed with fly ash and mineral powder and ecological fiber can effectively improve the anti-crack contractility, and work together for the early and late three crack resistance effect is remarkable.(4) Carbonation resistance test showed that the desert sand concrete the natural sand concrete carbonation resistance ability is stronger, because the desert sand particle size smaller, made of the concrete porosity decreases, and thus to a certain extent, improve its ability to resist carbonization. Ore with 15% and 15% replacement of fly ash cement, early carbonation resistance is low, the late due to the pozzolanic effect of fly ash, carbonation resistance increase. Ecological fiber can improve the anti-cracking performance of concrete, decrease the internal porosity of the concrete, which could improve the ability of the carbonation resistance of concrete.(5) Freezing-thawing resisting test showed that the desert sand concrete due to its natural defects can reduce concrete freezing-thawing resisting ability, mixed with fly ash and mineral powder concrete grading is more reasonable, join ecological fiber, can effectively improve the internal pore structure of concrete, so as to improve the desert sand concrete freezing-thawing resisting ability.