Study On Mechanical Properties Of Super High Strength Concrete In Special Road Section

In the highway construction of our country,cement concrete pavement and asphalt pavement are the most important pavement forms.Cement concrete pavement has the advantages of high strength and good durability,which is widely used in toll stations,service areas,long and long longitudinal sections of expressways and other sections with strict requirements on physical and mechanical properties.For these special sections of pavement,usually reinforced concrete and high formwork asphalt concrete are used,but it can not completely solve the problem of early damage of pavement structure in special sections Question.High strength concrete and ultra-high strength concrete have high strength and good performance.However,due to the high demand of mix design and maintenance technology and high cost,there is little research on the application of them in special road sections.In this paper,C100 cement concrete is taken as the research object,its mix proportion,mechanical properties,freeze-thaw performance are studied,and it is used in the design of cement concrete pavement.It is found that the thickness of C100 cement concrete pavement can be appropriately reduced and the durability can be significantly improved.Based on the DSP model of ultra-high strength concrete,ultra-high strength concrete is prepared by adding silica fume and superplasticizer("double mixing").First,the performance test of raw materials is carried out to verify the basic indicators of each raw material to ensure that the raw materials meet the requirements of the specification and can be used to prepare ultra-high strength concrete.Then,according to the orthogonal test design method,the best C100 mix proportion scheme is determined.On this basis,the determined C100 concrete is tested for compressive strength,splitting tensile strength,flexural strength,freeze-thaw cycle,etc The internal shape,pore structure and interface transition zone of ordinary concrete and ultra-high strength concrete were observed by SEM.Finally,the cement concrete pavement structure was designed and the pavement thickness of ordinary concrete,high strength concrete and ultra-high strength concrete was analyzed.The results show that the mixture ratio of ultra-high strength concrete C100 is:cement: water: Sand: Stone = 550:110:721:1128,in which the content of silica fume is 10%,the mechanical properties of the concrete meet the design requirements,silica fume can effectively improve the mechanical properties of the concrete,and make the internal structure of the concrete more dense;the thickness of the cement concrete pavement layer designed by ultra-high strength concrete can reach 19.2cm,with a ratio of Ordinary concrete pavement is 24.2% thinner than high-strength concrete pavement,15.8% thinner.When the number of freeze-thaw cycles is 800,the mass loss rate of ultra-high strength concrete is only 1.34%,which shows that ultra-high strength concrete has excellent frost resistance.It provides a new way for the application of ultra-high strength concrete in the special road pavement structure.