Development And Engineering Application Of GFRP Waterproof Split Bolt

In this paper,a large number of surveys and researches are conducted on the problem of maintaining the local decorative effect of fair-faced concrete structures,the waterproofing of detailed nodes in construction projects,the construction process characteristics and waterproofing properties of split bolts.Based on the full understanding and research of the process of molding fiber-reinforced plastic(FRP)materials,the mechanical properties and durability,it was found that a new type of split bolt can be developed to solve the above problems by making full use of the low shear strength of FRP materials for easy construction,corrosion resistance and rust-free characteristics.The main research contents and achievements of the article include:Firstly,GFRP is selected as the main material to make new type GFRP split bolts through the analysis of the characteristics of the FRP material forming process,the cost of FRP material,and the traditional features of the split bolt construction process.The basic dimensions of the new GFRP split bolts were determined by the mechanical performance test of the GFRP bolt and the mechanical analysis of the formwork engineering system.Through calculation and analysis,it is shown that the torsional bearing capacity is the main mechanical control index of the new type GFRP bolts,and the diameter of the GFRP bolts should not be less than 14 mm.Afterwards,according to the different waterproof requirements for the split bolts,three new types of GFRP split bolts were made separately.Secondly,through the permeability test of the split bolt-concrete bond interface,the antiseepage performance of various new GFRP split bolts and traditional split bolts is compared and analyzed.Different seepage mechanics models were established and the seepage properties and mechanical parameter of the various types of bolt-concrete bond interfaces were discussed.The results show that the interfacial permeability coefficient of the split bolt-concrete was greater than the concrete itself,and the overall permeability coefficient of the bolted concrete interface is in the range of 10-5~10-9cm/s,the seepage flow of the bolted-concrete bond interface is basically meet the laminar flow,which conforms to the cubic law.In addition,the dimensions of the water-expanding rubber water-stopping rings of the assembly GFRP waterproof split bolts were optimized and analyzed.And the optimal assembly size for waterexpanding rubber water-stopping rings was obtained.Thirdly,the effects of high-low temperature damp-heat cycle,freeze-thaw cycle and impregnating-drying cycle accelerated corrosion conditions on the permeability of the split bolt-concrete bond interface were tested and analyzed.The test results show that under the above three corrosion conditions,the permeability of the bolt-concrete interface has caused certain adverse effects,Freeze-thaw cycle and Impregnating-drying cycle accelerated corrosion conditions are the key factors affecting the permeability of waterstop bolts.GFRP waterstop bolts have better impermeability under long-term accelerated chloride ion corrosion conditions than traditional waterproof split bolts.Finally,through the concrete full-scale wall test and engineering case,the construction efficiency and construction effect of various types of split bolts were compared and analyzed,and the waterproof and permeability performance of the split bolts was tested through the fullscale low-pressure concrete wall penetration test.The results show that: GFRP waterproof split bolts and traditional full thread waterproof split bolts and traditional full thread split bolts have better impermeability and waterproof performance;The new GFRP split bolts have the advantages of high construction efficiency and good concrete appearance.