Experimental Study On Durability Of Basalt-PVA Hybrid Fiber Concrete

Concrete has gradually become an essential building material in engineering construction and is widely used in civil engineering because of its superior working performance.The extensive use of concrete has gradually exposed its shortcomings in durability.The damage of building structure caused by the lack of concrete durability can be seen everywhere in daily life.How to improve the durability of concrete has also become a research hotspot in the field of civil engineering.At present,in the aspect of improving concrete durability research,the fiber mixed with concrete to improve its durability has become a research direction,research mainly focus on basalt fiber,steel fiber,polypropylene fiber,carbon fiber and some hybrid fiber,etc.,but of basalt and pva hybrid fiber concrete does not have many research reports.Based on the natural Science Foundation project of Liaoning Province(2015020214),the basic mechanical properties and durability of basalt and polyvinyl alcohol hybrid fiber concrete(PVA)were tested and studied in this paper,and the concrete life prediction analysis was carried out.The specific work is as follows.Basalt fiber and polyvinyl alcohol fiber were added into C40 concrete in the form of single and mixed admixture.A total of 16 specimens with volume admixture of 0.2%,0.4%,0.6% and mixing ratio of 1:1,1:2 and 2:1 were prepared.In this paper,28 d mechanical property test,sulphate corrosion test,chloride ion permeation test and frost resistance test of concrete were carried out.Combined with the test results,the influences of fiber content and hybrid ratio on concrete properties were analyzed.The following conclusions are drawn from the experiments:When basalt and PVA fibers are mixed into matrix concrete,the 28 d compressive strength of concrete is lost.The splitting tensile strength was slightly increased.The improvement effect on the flexural strength of matrix concrete is the most obvious,among which the improvement effect of mixed fiber is better than that of single mixed fiber.Basalt fiber and polyvinyl alcohol fiber have significant influence on the sulfate corrosion resistance of concrete.Analysis results show that the matrix of fiber into concrete compression strength against corrosion resistance coefficient to promotion effect,the hybrid fiber series 2-1 in the fiber content is 0.2% of the 15 d sulfate is the most significant effect of ascension in the dry wet cycling test,2:1 hybrid fiber in 30 d sulfate content was 0.2% of the most significant effect of ascension in the dry wet cycling test;Fiber has an increasing effect on the mass change rate of concrete.Its 1:2 hybrid fiber series has the largest mass increase in 15 d sulfate dry-wet cycle test when the fiber content is 0.4%,and its 1:2 hybrid fiber series has the largest mass increase in 30 d sulfate dry-wet cycle test when the fiber content is 0.2%.No matter the strength loss is improved or the quality loss is improved,the performance effect of hybrid fiber is better than that of single doped fiber.Electric flux test of concrete specimen is adopted to improve the resistance to chloride ion permeability test,the analysis results show that basalt fiber resistance to chloride ion permeability of concrete is superior to the improvement of pva fiber,hybrid fiber form is better than single doped form,its 0.4% dosage of 2:1 hybrid fiber improves the best effect,the chloride ion permeability evaluation for "low".After 50 and 150 freezing-thawing cycles of test specimens,it can be seen that the improvement effect of hybrid fiber on compressive strength loss and mass loss is better than that of single blended fiber.With the increase of freezing-thawing cycle,the improvement effect of compressive strength loss and quality loss was more obvious,and the effect of hybrid fiber was more obvious.The results show that the service life of plain concrete is less than 60 years and that of most other fiber concrete specimens is more than 60 years.Compared with the single mixed fiber,the mixed fiber content and mixing ratio have better effect on the concrete life extension.Using dry-wet circulation-sulfate corrosion cycle formula for various series fiber concrete sulfate erosion life prediction,the following conclusion: the mixed fiber can prolong the service life of concrete,the life prediction results of hybrid fiber concrete is generally greater than single doped fiber concrete,including a 2-1 hybrid fiber concrete and best under 0.2% of the fiber content,concrete life prediction results of 78.49 years.