Study On The Mechanical Properties Of BFRP Reinforced Coral Reef And Sand Concrete Structural Members

Marine reef environment is a severe environment coupling with a variety of unfavorable factors,such as high temperature,high humidity,high salt fog and chloride ions.The durability problem of traditional reinforced concrete structure is prominent under the harsh reef environment.The actual service life of the building is much shorter than the designed service life.In addition,the construction cost of islands and reefs is still high due to the long distance transportation of concrete aggregates and fresh water from the mainland.These factors seriously restrict country’s large-scale development and construction of the South China Sea.Basalt fiber reinforced polymer(BFRP)is lightweight,high strength and excellent corrosion resistance,so it provides a new solution for handling with the durability problem of island structures.Meanwhile,the use of coral reef and sand to make concrete can not only greatly reduce the cost of the construction of the island reefs,but also avoid considering the effect of chloride ion on the BFRP materials.Based on this background,this paper combines the Coral Reef and Sand Concrete(CRSC)and the BFRP materials,studies the mechanical properties of BFRP reinforced CRSC structure.The experiment is mainly divided into there parts: the basic mechanical properties of CRSC,the mechanical properties of BFRP reinforced CRSC two-way slabs and the durability of BFRP bars reinforced CRSC beams,the specific research contents and achievements are as follows:1.Through water cement ratio,age,cement grade,aggregate gradation and other research parameters,concrete cube compressive strength test was carried out.The test shows that the destruction interface of CRSC is mainly coarse aggregate fracture;the strength increases with the decrease of water cement ratio;CRSC has obvious early strength performance.Combined with construction requirements,the mix ratios of C30 and C40 CRSC were given.2.Static tests on 6 BFRP bars/grid reinforced CRSC two-way slabs under concentrated loads were carried out.The test shows that the ultimate bearing capacity is not directly related to the limit state of reinforced materials.Under the same fiber content,the stiffness and cracking load of BFRP grid reinforced CRSC two-way slabs is greater than that of BFRP bars reinforced slabs owing to the integrated production process that improves the integrity of the BFRP grid.3.BFRP bar reinforced CRSC beams were tested through accelerated corrosion in dry-wet cycles.The corrosion temperature was 30℃,45℃ and 60℃,and the age of corrosion was 2 months,4 months and 6 months.The test results show that after 6 months’ s corrosion,corrosion and expansion of the stell tensile longitudinal reinforcement and the shear stirrups have occurred,but BFRP bars have no obvious change.After dry-wet cycles,the failure mode of BFRP beams has changed due to the degeneration of bond properties of stirrups.The maximum crack width of test beam after dry-wet cycles is greater than that of contrast beam.The stiffness of all beams increased in varying degrees.The main reason is that the coupled load makes the plastic deformation of the beams,which is equivalent to the application of prestress on the beams.4.Construction requirements of BFRP reinforced CRSC structure were organized and the feasibility of building industrialization for the construction of islands and reefs was analyzed.The analysis shows that the new building industrialization in South China Sea can be entirely realized with marine elevated platform technology,precasting and splicing technology of cross-sea bridges and industrial production technology of buildings.