Experimental Research On The Resistance Of Cotton Straw Fiber Concrete To Sulfate Erosion

The durability damage of concrete caused by salt erosion has attracted more and more people’s general attention,and related experimental studies have been carried out.However,due to the large differences in concrete durability damage under different concrete materials and different working conditions,the current research results have not yet formed a perfect theoretical system.Based on this,this paper tests the macro-mechanical properties of cotton straw fiber concrete with different dosages after curing for 28 days,finds out the cotton straw fiber concrete(PFC)with the best macro-mechanical properties,and simulates the performance with plain concrete(PC).The erosion characteristics of the natural erosion mechanism and the dry-wet cycle mechanism in the sulfate erosion environment are analyzed.The strength,quality,relative dynamic elastic modulus and apparent changes of the two concretes under different erosion mechanisms are analyzed with different erosion ages.And the change law of different dry and wet cycles,and finally with the help of SEM scanning technology,reveal the microscopic damage mechanism and damage evolution law of concrete materials under the sulfate erosion environment from a microscopic point of view.The performance of natural erosion mechanism and dry-wet cycle mechanism of plain concrete and cotton straw fiber concrete in sulfate erosion environment was discussed in depth from the macro and micro levels.The main conclusions are as follows:(1)When the plant fiber content is 2.0 kg/m3,the macro-mechanical performance is the best.The three maximum strengths are 39.16MPa,2.86MPa,and 4.26MPa,respectively,and the increase is 17.95%,24.89%and 32.71%.(2)The macro performance of plant fiber concrete is better than plain concrete under the same erosion mechanism in the sulfate environment.On the one hand,it has better mechanical properties against sulfate erosion.On the other hand,plant fiber can be mixed into concrete.To a certain extent,it can delay the corrosion damage of the concrete caused by sulfate.(3)The compressive strength,splitting tensile strength,quality and relative dynamic elastic modulus of plain concrete and plant fiber concrete under the two erosion mechanisms all show a "two-stagen" trend of first increasing and then decreasing,but plant fiber The degree of concrete decline is slightly slower and the peak erosion age or dry-wet cycle period appears later.(4)The test results with the help of SEM electron microscope scanning show that the macroscopic performance degradation of concrete is the macroscopic reaction of the microstructure change,and the change rule of the microstructure is consistent with the change rule of the macroscopic result.