Research On Fiber Reinforced Self-Compacting Concrete Applied To Prefabricated Wallboard

The modernization of the construction industry is the direction of development of construction industry in our country. Development of prefabricated component is a necessary way to realize the modernization of the construction industry. Prefabricated wallboard is the foundation of the modernization of the construction industry. At present, the research on prefabricated wallboard in the field of construction engineering is one of hotspots, mainly concentrated in the strength, durability, use properties(thermal insulation, sound insulation, fire) of the prefabricated wallboard, but the research on fiber reinforced self-compacting concrete applied to prefabricated wallboard is seldom reported.In this paper, a new prefabricated porous wallboard with a large number of surface reserved holes and adopting fiber reinforced self-compacting concrete as main material is presented. In this paper, the preparation of self-compacting concrete is first started, through compatibility test of water reducer and cement, the saturation point of the poly carboxylic acid high-efficiency water reducer is determined. Mix proportion of self-compacting concrete is optimized by orthogonal test, to determine the optimal combination of configuration parameters(water binder ratio, binder content, fly ash content, sand ratio and water content of water reducer). The research by adding thickening agent is carried out to solve the problems that the self-compacting concrete is easy segregated and bleeding. By changing the amount of water reducer and sand ratio, self-compacting concrete is still able to maintain good working performance after adding polypropylene fiber and micro steel fiber. The influence law of two kinds of fibers on the performance of self-compacting concrete is studied, in order to provide technical support for the application of fiber reinforced self-compacted concrete in prefabricated wall panels.The main research results of this paper are as follows:(1) Prepared to fiber self-compacting concrete meeting the new prefabricated porous wallboard and its performance index for compressive strength reach 50 MPa, splitting tensile strength can reach 3Mpa, extended degree for 650 mm, T50 flow time for 6s, U type box filling height for 320 mm, V shape instrument through time for 10 s.(2) The preparation parameters of self-compacting concrete are determined, of which the saturation dosage of polycarboxylate water reducer is 2.8‰, water to cement ratio is 0.4 and cementitious material is 520kg; the best amount of fly ash content is 30% and sand ratio is 52%.(3) Add increased thickener is a key technology to solve the problems in the segregation and bleeding problems of fiber self-compacting concrete, and the best dosage of thickener is 0.4‰;(4) Under the condition of keeping the self-compacting concrete working performance after fiber incorporation, the linear relationship between the amount of polypropylene fiber and the amount of water reducer is y=4.4054x+2.7162 and the linear relationship between the amount of fine steel fiber and the sand ratio is y=0.13x+0.464. The optimum volume content of polypropylene fiber(fiber accounted for the volume fraction of fiber reinforced concrete) is 0.1%, The optimum volume content of micro steel fiber is 0.4%.(5) With the increase of the content, compressive strength and elastic modulus of polypropylene fiber reinforced self compacting concrete first increase and then decrease and the bending strength and tensile strength present an overall upward trend. With the increase of dosage, compressive strength and splitting tensile strength of micro steel fiber reinforced self compacting concrete increase first and then decrease. Flexural strength and elastic modulus present an overall upward trend.(6) Through the flat restraint test, it is concluded that the polypropylene fiber is superior to the micro steel fiber in the control of the crack;(7) It is proved that the application of fiber self-compacting concrete in prefabricated porous wall plate is feasible through the production of porous concrete slab.