Experimental Study On Durability Of Basalt-cellulose Hybrid Fibre Concrete

Concrete has good compressive strength,easy material,easy to form,can form a good bearing member with steel,widely used,the demand for concrete is also relatively large,used in construction engineering,road engineering,bridge engineering,hydraulic and hydropower engineering,station,airport,military applications and other aspects.However,the problem of insufficient durability of concrete will lead to the destruction of the structure of buildings.Therefore,scholars improve the durability of concrete by adding fibers into the concrete matrix.In this paper,basalt fiber and cellulose fiber were mixed into C30 concrete matrix by single mixing method,and the basic mechanical properties,high temperature resistance,durability and durability life prediction of concrete were carried out.The main contents of the study are as follows:(1)Taking the mass content of basalt fiber and cellulose fiber as the variable,the mechanical properties of the test block were experimented.The results show that the 28 d compressive strength of concrete is lower than that of plain concrete in the cube compressive strength test regardless of the single fiber or the mixed fiber.After adding fiber,the splitting tensile strength of concrete is improved to a certain extent.The flexural strength of fiber reinforced concrete is higher than that of plain concrete,and the effect of mixed concrete is better than that of single concrete.(2)The mechanical properties of concrete after high temperature were experimentally studied with the mixing amount of basalt fiber and cellulose fiber and the temperature as variables.Results show that when the temperature reaches 400 incorporating fiber to peak ℃compressive strength of concrete,normal concrete when the temperature of 200 ℃and reached the maximum value,when the temperature exceeds 200 ℃,both single doped fiber concrete and compressive strength of hybrid fiber reinforced concrete were reduced with the increase of temperature,incorporating fiber concrete has good resistance to high temperature performance.After high temperature,the mass loss of the test concrete with fiber is more than that of plain concrete,and the mass loss increases with the increase of temperature.(3)The mechanical properties of concrete blocks were studied after 15 times of sulfate dry-wet corrosion and 30 times of sulfate dry-wet corrosion respectively,with the mass content of basalt fiber and cellulose fiber as variables.The results show that the basalt fiber and cellulose fiber can enhance the compressive strength of concrete after the cyclic dry-wet corrosion of sulfate.When the content of basalt is 2kg/m~3 and the content of cellulose is1kg/m~3,the compressive strength and corrosion resistance coefficient of the concrete test block can be improved the best under the condition of 15 times of cyclic sulfate corrosion.When the content of basalt cellulose in the hybrid fiber combination is 6kg/m~3 and 1kg/m~3,respectively,the compressive strength and corrosion resistance coefficient of the concrete test block can be improved best under the condition of 30 cycles of sulfate dry/wet cycling corrosion.(4)After 50,100 and 150 freeze-thaw cycles of basalt fiber and cellulose fiber as variables,the mechanical properties were tested.The results show that the frost resistance of concrete mixed with fiber is stronger than that of plain concrete.After 50 freeze-thaw cycles,the reinforced effect of mixed fiber is better than that of single fiber.When the mass content of basalt fiber and cellulose fiber is 2kg/m~3 and 1kg/m~3,respectively,the compressive strength loss of concrete is the least and the improvement effect is the best.After 100 freeze-thaw cycles of concrete tests,the good effect of improving the compressive strength loss of concrete is that when the basalt content is 4kg/m~3,the cellulose content is 2kg/m~3,and when the basalt content is 6kg/m~3,the cellulose content is 1kg/m~3,the compressive strength loss of concrete is 7.4%.After 150 freeze-thaw cycles,the best combination for improving the compressive strength of concrete test blocks is that when the basalt content is 4kg/m~3 and the cellulose fiber content is 2kg/m~3,the compressive strength loss is 6.3%,which is 33% higher than that of matrix concrete.After 50,100 and 150 cycles of freeze-thaw tests,the mass loss of concrete blocks with fiber incorporation is lower than that of reference concrete.(5)Based on the freeze-thaw cycle data and the life prediction models of concrete at home and abroad,the failure life of each series of fiber reinforced concrete in freeze-thaw cycle is predicted.The results show that the addition of fiber can improve the durability of concrete after freeze-thaw cycle damage and increase its life span.The effect of mixed fiber is stronger than that of single fiber,and the life span of mixed fiber is more than 90 years.The durability of sulphate was evaluated based on the experimental data of dry/wet cycle of sulphate,the research results at home and abroad and the life prediction model of freeze-thaw cycle.Results show that the mixed with fiber can improve sulphate dry-wet circulation after the destruction of concrete durability in order to enhance their life,mix to improve the effect of doped fiber is better than single doped fiber,hybrid fiber series in the basalt fiber fiber and cellulose fiber dosage respectively after 6 kg/m~3 and 1 kg/m~3 after its best,sulfate corrosion dry-wet circulation conditions predicted its lifespan forecast of 78.17 years.