The Research On Ultra High Performance Decorative Concrete

Ultra high performance concrete is a kind of cement-based composite material with excellent durability and toughness,high strength and so on.It has been widely used in many engineering practice at home and abroad.To further expand the scope of application of ultra high performance concrete and ordinary concrete to develop toward a better direction,this paper introduces the ultra high performance decorative concrete based on ultra high performance concrete.According to the practical application of decorative concrete and fiber reinforced theory,the effects of different content and different length of four fiber ratio:alkali resistant glass fiber(GF fiber),ultra high strength high modulus polyethylene fiber(PE fiber),polypropylene fiber(PP fiber),alkali basalt fiber(referred to as BF fiber)effect on ultra high performance concrete fluidity,mechanical properties and part of the decoration performance,determined the best performance and the optimal fiber length to diameter ratio of mixing amount.In this paper,the concrete extrusion molding method for vacuum vibration,the molding process parameters of different influence on the strength and decorative performance of ultra high performance concrete,the optimal parameters were determined preliminarily.In this paper,the effects of two different curing systems of steam curing and hot water curing on super high performance concrete are compared.The results show that:(1)The influence of different fibers on the fluidity of the new slurry is basically similar,that is to say,with the increase of the content of the mixture,the fluidity will be significantly reduced.In order to meet the ultra high performance concrete decorative plate rapid prototyping and vacuum vibration extrusion molding method,the design of water gel is relatively low,so the fresh paste fluidity than the general ultra high performance concrete to low fluidity.But the same kind of fiber in the same dosage,with the increase of the length of fiber winding each other,the possibility of making bigger,therefore reduce the fiber dispersion and aggregation are more likely to happen.Therefore,under the same dosage,the influence of long fiber on the fluidity of UHPC is slightly larger than that of short fiber.(2)Through the compression test,it is found that different fibers have different effects on the compressive strength of super high performance concrete.With the increase of fiber content,the compressive strength of fiber reinforced concrete will increase,but the growth rate will slow down,and the compressive strength will not increase with the increase of the content of a certain amount of concrete.With the same amount,the same kind of concrete with the increase of fiber length has a slight increase in compressive strength.(3)Through the bending test,it is found to have different effects on different fibers of ultra high performance concrete flexural strength of the glass fiber;ultra high performance concrete and PE fiber ultra high performance concrete flexural strength in fiber reinforced concrete.When the fiber content is below 1%,the flexural strength of concrete is almost the same,and the flexural strength is very fast in the process of 1%to 1.5%.The flexural strength of concrete with the same volume and the same kind of concrete increases with the increase of fiber length.(4)Molding process parameters and curing system have some influence on the physical and mechanical properties of ultra high performance concrete.In a certain range,with the increase of the forming pressure,concrete compressive strength and flexural strength are improved,but beyond a certain range,the compressive strength,flexural strength growth is slow;the vibration time in the forming process have important influence on the formation of UHPC and the physical and mechanical properties.Compared with 90 degrees hot water curing,under the condition of steam curing at 90 degrees Celsius,the compressive strength of concrete is high and the flexural strength is improved greatly.(5)Drying shrinkage test results show that different fibers have a similar effect on reducing the drying shrinkage of super high performance concrete.Among them,the drying shrinkage of glass fiber super high performance concrete is the lowest.However,the performance of super high performance concrete with silica fume is lower than that of super high performance concrete.(6)The test of thermal shock resistance and other decorative properties results show that the performance of glass fiber super high performance concrete and PE fiber super high performance concrete is better than that of other super high performance concrete.