Experimental Study On Axial Compression Performance Of Coral Sand Concrete Mixed With Seawater In Marine Environment

In recent years,China has increased the exploitation and utilization of marine resources,with the continuous development of island reef construction projects,a large number of infrastructure projects have been put on the agenda,and the corresponding use of building materials has also been increasing.For islands and reefs far from the mainland,all the materials needed to be transported from the mainland,which is too expensive.Compared with traditional river sands and gravel,using a large number coral reefs,sand and seawater and other raw materials that exist near the island reef can not only save construction time,meet the requirements of rapid construction,but also greatly reduce the economic cost due to material transportation.Therefore,the research and development of marine aggregate concrete can achieve the purpose of drawing on local resources,reducing costs and shortening the duration of construction,which is of great significance to the further construction of marine engineering in China.In order to study the axial compression performance of coral sand concrete mixed with seawater in marine environment,123 concrete cylinder block with 11 formulations were designed and made with the replacement substitution rate of fine aggregate,the type of water used for mixing,the position of later placement and exposure time as the change parameters,and the axial compression test was carried out.The characteristic phenomena before and after exposure in the marine environment of each test block were observed,as well as the destruction process and final destruction form of each test block at different exposure time.the characteristic point parameters such as the collapse,the whole loading process stress-strain curve,peak stress,peak strain,displacement delay,and energy dissipation were obtained.And the influence law of each change parameter on the work and mechanical performance of coral sand concrete is analyzed in detail.Finally the expression of the stress strain curve of coral sand concrete is obtained by software fit.The results show that:(1)In the coastal environment,the stress and deformation performance of coral sand concrete is better than that of river sand concrete.(2)Mixing water type on ordinary river sand concrete impact is not obvious,but the use of seawater mixing can make coral sand concrete peak stress of about 15% increase,so in the sea-facing environment using seawater mixed coral sand concrete can meet the stress demand.(3)The elastic mode of concrete in the marine environment has increased by different magnitudes,and under the atmospheric conditions of the sea,the deformation performance of low coral substitution rate concrete is better than that of the other two regions.(4)At the same time,the stress variation of the atmospheric environment test block in the sea fluctuates the most,but the stress performance and deformation performance are the best.(5)Seawater immersion behavior will reduce the concrete strain,but the higher the coral content,the smaller the magnitude of the change;Taken together,it can be seen that the replacement rate of 30% coral sand concrete is most likely to be applied to engineering practice.Finally,according to the test results,reasonable suggestions are provided for the development and application of new materials for the construction project of the lower islands in the marine environment,and basic reference is provided for the preparation of the subsequent marine aggregate concrete specification.