Study Of The Properties Of Bio-coral-rich Concrete

As the foundation of marine resources development,island construction is an important link to accomplish the national goal of "Strong Ocean State".Due to the special geographical location of the island reefs,there is a lack of sand,gravel and fresh water required for construction.Under the condition of conforming to the policy and environmental requirements,coral debris is obtained as coarse and fine aggregates through dredging channels,etc.,and Coral aggregate seawater concrete(CASC)is prepared by seawater mixing to solve the problem of material scarcity in island construction projects.However,island construction is affected by marine climate and construction conditions,and various conditions make the performance of seawater concrete in the actual construction process and the laboratory have a large difference.In order to better solve the problem of coral concrete engineering application,this thesis uses the amount of Sargassum mixture,curing conditions,water-cement ratio and age as the research parameters to make the specimens of coral concrete containing marine organisms and analyze the influence of the above parameters on the mechanical properties and durability performance of coral concrete containing marine organisms based on the test.The main research contents are as follows:(1)Workability tests were carried out with reference to the concrete test specification,and slump,expansion and air content tests were conducted for each of the eight test groups to obtain workability test data of each concrete mix.The analysis of the test results showed that with the increase of Sargassum impurities admixture,the overall trend of fresh concrete fluidity decreased.Under the same water-cement ratio conditions,the air content of coral concrete was not significantly changed by the admixture of Sargassum impurities due to the high porosity of coral aggregate surface.The air content of concrete showed an increasing trend with the increase of water-cement ratio.(2)The basic mechanical properties of bio-rich coral concrete were tested to investigate the effects of different Sargassum admixtures,water-cement ratio and age on compressive strength,axial compressive strength and splitting tensile strength.The relationship between compressive strength and axial compressive strength and splitting tensile strength of bio-rich coral concrete was obtained by regression analysis,and the equations for calculating axial compressive strength and splitting tensile strength based on cubic compressive strength with different impurities of Sargassum were established.(3)The compressive corrosion resistance coefficient,mass loss rate,relative dynamic elastic modulus and damage layer thickness were used as the evaluation indexes of concrete performance under the dry and wet cycle erosion mechanism of sulfuric acid solution.The results showed that the mass loss rate did not change significantly at 2%impurity content of Sargassum,and had a large effect on both ultrasonic sound velocity and compressive strength of concrete when the impurity content reached 4%.(4)Based on Fick’s second law and the analysis of sulfate ion permeation test results,the free diffusion model of sulfate ions in coral concrete was established,and the numerical simulation of sulfate ion diffusion in coral concrete specimens was carried out using the finite element software Comsol,and the simulation work was carried out on the basis of the existing test data,and the simulation results were also compared and analyzed with the actual test results.