Experimental Study On Mechannical Properties Of Modified Cement Coral Mortar

Since the implementation of the "marine power" strategy,China has carried out large-scale island engineering construction on islands and reefs in the South China Sea.However,with the rapid development of island engineering construction,the only use of traditional concrete and other materials for construction not only increases the transportation cost of materials from inland to the island,but also delays the construction period due to adverse factors such as wind and waves.The South China Sea islands are rich in coral reef sand resources,so the utilization of coral reef sands for island engineering development and construction has obvious advantages.Due to the complex environment of the remote island reef project and the shortcomings of coral concrete itself such as low strength and high brittleness,it is of great significance to find an economical and efficient method to improve the performance of concrete and mortar prepared with coral sand in order to meet a wider range of engineering applications.Therefore,this subject takes cement mortar prepared by coral sand as the research object and systematically studies the modification effect of PVA fiber,metakaolin and slag on Cement Coral Mortar(CCM).The main research contents and conclusions of this article are as follows:(1)The effects of PVA fiber,metakaolin and slag on the basic mechanical properties of CCM were studied.(1)Regarding PVA fiber,metakaolin and slag as the main factors,the flexural and compressive test were performed under the condition of single admixture.The results show that: within the selected range,the optimal amounts of PVA fiber,metakaolin,and slag are 0.10vol%,15wt%,and 15wt%,respectively.An appropriate amount of PVA fiber,metakaolin,and slag can effectively improve the flexural strength and compressive strength of CCM.(2)Using the response surface optimization test design method,CCM test specimens of different components were prepared and subjected to flexural and compressive tests.The results show that: within the selected range,the optimal blending ratio of PVA fiber-metakaolin-slag is 0.11vol% of PVA fiber,16.60wt% of metakaolin,and 14.99wt% of slag.The content of metakaolin has the most significant effect on the flexural strength and compressive strength of CCM.The interaction between the amount of metakaolin and the amount of slag is the most significant.(2)The effects of PVA fiber,metakaolin and slag on the dynamic mechanical properties of CCM were studied.(1)The drop weight impact test was performed on CCM specimens mixed with PVA fiber,metakaolin and slag alone.The results show that: Adding appropriate amount of PVA fiber can improve the brittleness of CCM specimens,delay the formation and expansion of impact cracks,and then significantly improve the impact resistance of CCM specimens.Adding metakaolin or slag can effectively improve the initial cracking resistance of CCM specimens,but has no obvious effect on improving its brittleness.(2)Based on the impact test,a two-parameter Weibull distribution model was introduced to perform fitting analysis on the number of impact resistance of each group of test pieces.The results show that: The impact resistance numbers of each group of specimens are subordinated to the two-parameter Weibull distribution.