Research On The Influence Of Mechanics And Durability Of Natural Lightweight Aggregate Concrete By Mixing Metakaolin

There are a huge amounts of natural pumice in the region of Inner Mongolia, and natural lightweight aggregate concrete are used more and more widely in the project, although having such characteristics of light weight, the intensity of it is much lower than the same label of ordinary aggregate concrete. Based on this point, the metakaolin are mixed in natural pumice lightweight aggregate concrete to study the affects to its mechanical properties and durability by such admixtures.Lightweight aggregate concrete is made up of4groups, which are mixed with metakaolin of0%10%,15%,20%to replace the same quality of sand. Firstly, in terms of mechanical properties, measuring the compressive strength of standard age of3d,7d,14d,28d,60d,90d and the splitting tensile strength of standard age of3d,7d,28d, then comparing various dosage strength values at each age, and each group were compared with baseline group. In the mechanical properties test we obtain that the optimal dosage of metakaolin is15%of the cementitious material by fitting the curve. In terms of durability, studied the impact of dynamic elastic modulus and mass loss at25-200times freeze-thaw cycles under clear aqueous solution which could reflect the impact of frost resistance after mixed the metakaolin. The results show that the metakaolin optimal dosage is15%of the cementitious materia. In addition, the scanning electron microscopy test of the specimen which treated by freeze-thaw cycles are carried out to make some microscopic analysis. Simultaneously, the microscopic mechanism of metakaolin could improve the frost resistance and properties of lightweight aggregate concrete are analyzed. Through analysis of frost resistance test data, although there are some human and environment errors, after excluding gross error based on the pull up guidelines, the test data are more accurate and convincing.In addition, the15%content of metakaolin concrete specimens are selected to be immersed in MgSO4solution and NaCl solution separately in the wet-dry cycle test of lightweight aggregate concrete. Then the compressive strength and mass loss of both erosion blocks are measured in the wet-dry cycles. At last,according to the measured data variation and the stress-strain curve to study the anti-erosion mechanism of metakaolin in two kinds of solution.