Study On Mix Proportion Of Sea Sand Coral Concrete And Mechanical Properties Of GFRP Reinforced Short Columns

There are many coral islands and reefs in the South China Sea.Using coral,sea sand and other raw materials,in line with the idea of local materials,sea sand coral concrete has important theoretical and technical significance.In this paper,through the technical means of crushing coral aggregate,mixing concrete and the technical theory of lightweight aggregate concrete,the mix proportion of sea sand coral concrete is designed and optimized by the orthogonal design method,and the mix proportion of C20,C30,C35 and C40 Portland cement sea sand coral concrete is obtained.Because the sea sand coral concrete uses the sea sand coral and other raw materials from the sea,it is impossible to select the reinforcement as the internal support as the reinforced concrete in the selection of the reinforcement.In order to avoid the loss of the original performance caused by the corrosion of the reinforcement,GFRP reinforcement is selected to replace the reinforcement to prepare the GFRP reinforced sea sand coral concrete.In this paper,12 short columns of GFRP reinforced sea sand coral concrete under axial compression are designed and fabricated.The main research contents and conclusions are as follows:1.The mix proportion of sea sand coral concrete is designed and optimized.According to the test results,the factors that affect the cube strength of sea sand coral concrete are: water cement ratio > quality sand ratio > cement dosage > water reducer,and the mix proportions of C20,C30,C35 and C40 sea sand coral concrete are obtained.2.The influence of retarder and early strength agent on sea sand coral concrete is studied.The results show that after adding retarder,the slump of sea sand coral concrete is increased,and the initial setting time and final setting time of concrete are prolonged,and the setting time of concrete is also increased.After comparing the test data,it is found that the effect of retarder is the most obvious when the dosage is 0.075%.In terms of strength,before 7 days,the compressive strength of sea sand coral concrete with 0.05% retarder and 0.075% retarder is higher than that without retarder;after 7 days,the compressive strength of concrete with retarder is higher than that without retarder.In the aspect of early strength agent,the effect of early strength agent on the slump of sea sand coral concrete is relatively large,which shows that it has a great influence on the workability and fluidity of concrete,and the setting time also becomes shorter with the increase of the amount of admixture.With the increase of the content of early strength agent,the early strength of concrete has a significant improvement,and the effect on the 28 d strength is general.3.GFRP reinforced sea sand coral concrete column has no obvious omen in the process of compression,and GFRP reinforcement remains intact after the concrete is crushed.The bearing capacity of GFRP reinforced compression column increases with the increase of reinforcement ratio.Similarly,the reduction of stirrup spacing under the same reinforcement ratio is conducive to strengthening the bearing capacity of short columns.Through the research and analysis of this paper,it can be used for reference for the experimental study of sea sand coral concrete and GFRP reinforced sea sand coral concrete columns.