| The geographical environment of offshore engineering is complex,which is affected by the combined effect of high temperature,continuous load,corrosion,tides and so on.At the same time,the project is far away from the inland,and the construction resources such as sand,gravel and freshwater are relatively scarce.If the traditional building materials are used for construction,it will cause problems such as high transportation costs,difficult construction management and poor building durability.Therefore,in this article,it uses seawater instead of fresh-water,sea-sand instead of river-sand,coral instead of gravel,mineral admixture cement instead of ordinary Portland cement,GFRP bars instead of steel bar,which is suitable for offshore engineering.Additionally,it strives to effectively solve the problems of scarcity of construction materials and poor durability of structures in offshore engineering.The main contents of this paper are as follows:First of all,this paper studies the optimum aggregate gradation(coral,coral+coral sand+sea sand,coral+sea sand)of sea sand coral concrete and the physical properties of coral aggregate.The results show that the aggregate gradation of coral+sea sand has the highest compressive strength;the saturated water absorption rate of coral aggregate is 15%,and the bulk density is 934kg/m~3.Secondly,this paper nearly two hundred standard cube specimens are produced to obtain the design value of the Mineral admixture concrete with mixed ratio of concrete strength grade C20-C30.After comparing and analyzing the influence of water content of coral aggregate,net water-cement ratio,sand ratio,cementitious material types and air-entraining-plasticizer agent on the compressive strength and slump of concrete.The results show that:within the scope of this test,when the water content of coral aggregate is 12%,the concrete strength is the highest;the net water-cement ratio has little influence on the compressive strength but has a great influence on the workability of concrete;with the increase of the net water-cement ratio,the workability of concrete becomes better.When the sand ratio is 45%-55%,the slump of concrete increases with the increases of the sand ratio;when the sand ratio is 55%-60%,as the sand ratio increases,the concrete slump increases initially and then decreases later.The strength of fly ash concrete is higher than that of slag concrete and Portland concrete.Under the condition of adding air-entraining-plasticizer agent,the compressive strength and slump of concrete will be improved if the net water-cement ratio remains unchanged;the compressive strength of concrete will be improved with the decrease of mixing water;the amount of cementitious materials can be reduced with the same compressive strength,but the workability of concrete is poor.Finally,27 pull-out specimens were made to study the effects of different test methods,GFRP bars diameter,GFRP bars bond length,concrete compressive strength on the bond behavior of GFRP bars sea rock concrete.The results show that:within the scope of this test,the bond stress of double-bars symmetric pull-out specimens is less than that of axisymmetric pull-out specimens and Losberg pull-out specimens;the bond stress between GFRP bars and concrete decreases with the increase of diameter,the increase of bond length and the increase of concrete strength... |
