Mix Design And Property Of Coral Aggregate Concrete

The distribution of the South China Sea Islands is scattered but the location is very important.As a symbol of China's territorial sovereignty, these islands is also an important base for the development of marine resources, and the construction of the South China Sea and air transport relay station. Due to the distance from mainland and limitation of weather, transportation of freshwater and aggregate is difficulty.. The South China Sea islands are rich in coral reef resources. A large number of domestic and foreign literatures suggest that coral reefs, sand can meet requirements as concrete aggregate. So coral concrete is a good solution for construction on Sea Islands faraway from mainland.This paper is based on the domestic and foreign researches on ordinary concrete and lightweight aggregate concrete. Coral aggregates were firstly broken and by using rich slurry concrete theory, five kinds of concrete, that is C30, C40, C50 and C55 Portland cement coral concrete and C30 Magnesium Sulfate Cement Concrete were prepared. Basic performances were tested and main conclusions are as follows:1. Influence of crushing process and weathering of coral aggregate on its properties were investigated. It is showed that(1) Un-weathered coral exhibits superior strength and higher density compared with weathered coral. Bulk density and of un-weathered coral is 1.1 and 1.4 times of that of weathered coral, respectively.(2) Crushing process is beneficial. As a result of the crushing process, bulk density of coral is approximately 1% higher, the cylinder pressure strength is about 9.5% higher, the mud content is reduced by roughly 8%, and the content of needle particles is lessened by almost 20%.2. Factors that influenced the mix proportion were studied, and the impact in descending order is as follows: Pre absorption rate > Water cement ratio > sand ratio > the amount of total cementations material. Mix proportion of coral concrete with compress strength of C30, C40, C50 and C55 were obtained. Dependency of the compress strength on water cement ratio, the amount of total cementations material, and Mineral admixtures was also achieved by regression analysis.3. Mechanical properties of C30, C40, C50 and C55 coral concretes were tested, and it was found that both tension and compress strengths of coral concrete are higher than ordinary concrete with the same grade, and theirs axial compressive strength young's modulus were between ordinary concrete and light aggregate concrete; the Poisson's ratio were from 0.25 to 0.28.4.The relationship of basic mechanical properties of coral aggregate concrete were studied.The results showed that there were strong linear relationships between axial compressive strength and compressive strength, and so were tensile strength and compressive strength.The range of ratio of flexural strength and compressive strength was from 0.102 to 0.103. The relationship between elastic modulus and compressive strength of ordinary concrete formula, but changes the dynamic parameter value.5.At incremental portion, the stress-strained curve of coral aggregate concrete was similar to Portland cement concrete's, but at sloping portion, the stress-strained curve of coral aggregate concrete was more steeply than Portland cement concrete's, which accounted that coral aggregate concrete was more brittle than Portland cement concrete. The equation of sloping portion was as following: y=x/?-? +? ?+1?x?? 1?x 6. Mechanical properties of C25 Magnesium sulfate cement concrete and C30 Portland cement coral concrete were tested, and obtained the following rules and basic Magnesium sulfate cement C30 all the coral sea water concrete contrast: tensile compressive strength of basic Magnesium sulfate cement concrete whole coral sea water were greater than ordinary Portland cement with the strength of all coral seawater concrete. These fully illustrated that the basic magnesium sulfate could decrease the brittleness of Coral aggregate concrete, and give it a certain amount of toughness.