| The sandy water flow damages the concrete materials in the hydraulic structure,which not only seriously affects the function and the service life of the hydraulic structure,but also creates potential safety hazards and also brings a lot of maintenance costs.The existing anti-abrasion materials have problems such as low abrasion resistance,short service life,easy cracking,and low bonding strength.In order to solve these problems,at the same time,in order to adapt to the construction of high-head or even ultra-high head hydraulic structures,it is necessary to study a material with high abrasion resistance.Ultra-high performance concrete is a kind of cement-based composite material with extremely high mechanical properties and durability.Its ultra-high mechanical strength and durability make it applicable to construction at home and abroad,bridges,roads,and cover plates.Applied to the potential of impact-resistant and wear-resistant materials in hydraulic structures,but there are few studies on their performance in this area at home and abroad.In view of this,this paper studies the abrasion resistance of ultra-high performance concrete.Because the abrasion resistance test method in the current specification has a low flow rate,a long test period,and low test efficiency,a new test device and test method—water-sand method—was first proposed and developed.The performance of the concrete is subject to experimental studies that do not permit flushing flow rates and abrasion resistance.Through the orthogonal test,the effects of the composition of the cementitious material and the mix ratio parameters on the mechanical properties and abrasion resistance of ultra-high performance concrete were studied.Based on the orthogonal test,the comparison of the mechanical properties and the anti-abrasion performance between the mix ratio and the ordinary concrete and industrial production samples is preferred.Finally,the further research on the optimization performance and cost reduction of the ultra-high performance concrete is carried out.The main work carried out in this paper and the main results achieved are as follows:(1)The impact of different test parameters on the test results in the test method of anti-erosion performance was studied.The self-developed water-sand test method and test device were used.The results show that the water sand gun test method is suitable for testing ultra-high performance concrete.The anti-abrasion performance,with the test water pressure can be adjusted,the flow rate can be controlled,the test cycle is short,the test efficiency is high,accurate simulation of sandbearing water flow and other characteristics.(2)The influence of concrete type and strength on the abrasion resistance of concrete under different pressures was studied.The results show that the impact of the grinding pressure on the test results of water-sand method for testing the impact strength of concrete has a great influence.The suitable pressing pressure should be selected according to the type and strength grade of the concrete.The compressive strength and anti-abrasion performance of the concrete are obvious.Positive correlation.(3)Propose the use of wate-sand method to study the permitting non-washing flow rate of concrete,and obtain the critical flow velocity of concrete in the abrasion failure,and then study the influence of the concrete strength level on the allowable non-washing flow rate.The results show that there is a positive correlation between the permitted flow rate and the compressive strength of the concrete.The higher the concrete’s compressive strength,the greater its allowable non-washing flow rate.(4)Orthogonal test method was used to systematically study the effects of the composition and the mix ratio parameters of cementitious materials on the abrasion resistance and mechanical properties.The results show that the water-rubber ratio has the greatest impact on the abrasion resistance,followed by the sand-binder ratio,the steel fiber content and the silica fume content.Considering the strength performance,abrasion resistance and cost of ultra-high performance concrete,the mix ratio of ultra-high performance concrete is: silica fume content 15%,fly ash content 5%,slag content 10%,water-binder ratio 0.14,sand and cement ratio 1.3,steel fiber content 1.0%.(5)Comparatively studied the mechanical properties and abrasion resistance of ultra-high performance concrete and ordinary concrete,and industrial production samples.The results show that there is a good positive correlation between the anti-abrasion performance and compressive strength performance of concrete.The ultra-high performance concrete produced by the laboratory or the factory has better anti-milling performance than ordinary concrete and high-strength concrete.Under the condition of low hydrostatic pressure test,the abrasion resistance of ultra-high performance concrete is about 3 times that of C45 concrete,about 2 times that of C70 and CF70 concrete,and about 1.5 times that of C80 concrete.Under high hydrostatic pressure test conditions,the ultra-high performance concrete has about 2 times the impact abrasion resistance of C45 concrete,about 1.5 times that of C70 and CF70 concrete,and about 1.3 times that of C80 concrete.(6)The mechanical properties and anti-milling performance of the blending ratios of the reference blend ratio and inorganic inorganic curing materials,limestone powder and rubber powder were comparatively studied.The results show that the incorporation of self-made inorganic inner curing materials,limestone powder and rubber powder will reduce the mechanical properties and abrasion resistance of ultra-high performance concrete to a certain extent.The greater the content of self-made inorganic inner curing materials and limestone powder,the lower the compressive strength and abrasion resistance.The larger the amount of rubber powder is,the lower the compressive strength is,but the greater the abrasion resistance is. |
