Study On Shrinkage And Durability Of Manufactured Sand Concrete

The long-term performance and durability of concrete impact the service functionand lifetime of concrete constructions. The studies on the long-term performance anddurability of concrete have been the focus of attention and key issues of civilengineering, as well as the difficulty of realizing the high performance of the concrete.With the rapid development of infrastructure construction and the need for environmentprotection, the natural sand resources become more and more lack, and the use ofmanufactured sand become the trend in the future. The problems of long-termperformance and durability have become the key technical problems, which restrict theapplication and development of manufactured sand concrete. Therefore, strengtheningresearch on long-term and durability of manufactured sand concrete has importanttheoretical significance and practical value.The long-term performance and durability of manufactured sand concrete andnatural sand concrete are study in this paper which focus on the influence of MB value,crushed dust content on the dry shrinkage, the resistance to chloride penetration, frostresistance, carbonation resistance, sulfate attack resistance, and acid rain corrosionresistance of manufactured sand concrete. The products of sulfate attack wereanalysised by means of X-ray Diffraction (XRD) and Fourier Transform InfraredSpectroscopy (FTIR) methods. The major revealed law and main achieved results bythis study are as follows:①The induction period of cement hydration can be shorten by the crushed dust,which promote cement hydration in advance into the accelerated phase. And, thecrushed dust can promote the early hydration of cement.②When the MB value is in the range of0.6~1.8,with the increase of MB, the totalcracking area in a unit area of manufactured sand concrete increased, and thecontractibility rate of manufactured sand concrete at24h was gradually increased.③For the C40concrete, when the MB value is less than1.4, all of the chloride ionpermeability resistance, frost resistance, acid rain corrosion resistance, sulfate resistanceof manufacture sand concrete are better than these of natural sand concrete.④For the C40concrete, when the MB value is less than1.4, the compressivestrength of the manufactured sand concrete which measured at different test periodincrease with the increase of MB. After the same number of freeze-thaw cycle, the relative elastic modulus of manufactured sand concrete increase gradually with theincrease of the MB. The acid rain corrosion resistance of manufactured sand concreteincreased gradually with the increase of the MB.⑤When the fineness module is in the range of2.8~3.4, in influence of finenessmodule on the long-term strength and frost resistance of manufactured sand concrete isnot obvious.⑥When the curshed dust content is in the range of5%~15%, there is maximumvalue of the shrinkage rate of the C30manufactured sand concrete at10%. However,the shrinkage rate of the C50manufactured sand concrete decrease with the increase ofcurshed dust content which varied in the same range as C30.⑦Whenthe crushed dust content is in the range of5%~15%, for the C30manufacture concrete, the acid rain corrosion resistance of it increases with the increaseof crushed dust content. However this influence is not obvious for the C50manufactured concrete.