Experimental Study On Mechanical Properties Optimization Of Frost Resistant Vegetation Concrete

Building a high-quality ecological civilization is a long-term plan related to the well-being of the people and the future of the nation.Since the 14 th Five-Year Plan,ecological environmental protection is in a more important position,in the face of environmental problems brought about by ordinary concrete,experts and scholars have developed vegetation concrete to enhance the ecological benefits of concrete.On this basis,the research group developed freeze-resistant vegetation concrete in view of the problem that vegetation concrete is susceptible to freeze-thaw damage in the northern region,and improved the construction of the ecological environment at low temperatures.However,at present,the strength of antifreeze vegetation concrete is low,which restricts its promotion and application.In this paper,the mechanical properties of antifreeze vegetation concrete are optimized as the research objectives,and the cementing agent optimization experiment is first carried out,through the mortar test,on the basis of the compressive and flexural strength of the mortar specimen,the cementing agent with better cementing ability was selected,and the influence of the dosage change on the compressive strength of the concrete of the frozen vegetation was explored;secondly,the optimization test study of short-cut fibers was carried out,and the shortcut fibers were mixed into the frost-resistant vegetation concrete with different dosages,and the optimal dosage of short-cut fibers was determined on the basis of the compressive strength and porosity of the concrete specimens;finally,a four-factor four-level orthogonal test was designed,and the 28 d compressive strength,porosity and sedimentation phenomenon were used as the measurement indicators,and the mix ratio of concrete against frozen vegetation was optimized,through the analysis of variance,analysis of variance,and multiple logic regression,the influence of each factor on the three measured indicators was obtained;linear regression analysis is used to establish a linear regression equation between 28 d compressive strength,porosity and four factors;the optimal mix ratio was obtained by the Z-value comprehensive evaluation method,and the folding strength,freeze-thaw and p H value tests were carried out on the optimal mix ratio specimens,clarify the performance indicators of the optimal mix of anti-freeze vegetation concrete test pieces;scanning electron microscopy test study is carried out on the optimal mating test piece,from the microscopic level,the reasons for the improvement of the mechanical properties of antifreeze vegetation are revealed.The main conclusions of this article are as follows:（1）The compressive strength and flexural strength of the mortar specimens mixed with polymer emulsion are higher,and the effect of selecting polymer emulsion as a cementing agent is better;the compressive strength of freeze-resistant vegetation concrete 28 d shows a trend of first increasing and then decreasing with the increase of polymer emulsion mixing,when the polymer emulsion dosage is about 2%,28 d Compressive strength is at its highest.（2）The 28 d compressive strength of the frost-resistant vegetation concrete showed a trend of first increasing and then decreasing with the increase of the amount of short-cut fibers,and when the amount of short-cut fibers was about 1kg/m~3,the compressive strength of 28 d reached the highest;the porosity of frozen vegetation concrete showed a downward trend with the increase of short-cut fiber doping,but the decline was not significant.（3）The main and secondary factors affecting the compressive strength of the antifreeze vegetation concrete in 28 d are: the gelatinizing agent dosage> aggregate content coefficient>the water-glue ratio> the target porosity,among them,the binding agent dosage and aggregate content coefficient have a significant impact on the compressive strength of 28 d,and the target porosity and hydro-glue ratio have a significant impact on the compressive strength of 28d;the main and secondary factors affecting the porosity of the concrete of antifreeze vegetation are: aggregate content coefficient> gelatinizing agent dosage> target porosity > water-to-glue ratio,of which the aggregate content coefficient has a significant impact on porosity,and the amount of gelatinizing agent doping,target porosity and water-glue ratio have a significant impact on porosity.（4）According to the Z-value comprehensive evaluation method,the fifth group of orthogonal test was selected as the optimal mix ratio group,and its compressive strength of 28 d was 15.66 MPa,which was 28 d compressive resistance compared with the previous period of the research group The strength increased by 57.2%;the flexural strength is 4.26 MPa,which is 65% higher than that of the previous research group;the antifreeze grade is F250,which is20% higher than the antifreeze level of the research group;the porosity is 20.3%,and the porosity environment is low alkaline.（5）The linear regression equation between 28 d compressive strength,porosity and four factors has passed the validity test,and it can be obtained according to the linear regression equation: aggregate content coefficient,water-to-glue ratio,target porosity,and cementitious agent dosage have a negative correlation with the compressive strength of 28d;there is a positive correlation between aggregate content coefficient,hydro-glue ratio,target porosity,and cementing agent dosage on porosity.The sedimentation model between the sedimentation phenomenon and the four factors passed the validity test,and it can be obtained according to the sediment model: the aggregate content coefficient has a significant negative correlation relationship for the occurrence of the sediment,and the water-to-glue ratio has a significant positive correlation relationship for the occurrence of the sediment.（6）It can be obtained by scanning electron microscopy test: the surface of the cement hydration product mixed with polymer emulsion is covered with a large amount of hydrogenation condensate film,and the hydrogenation condensate film overlaps the hydration products with each other,making the structure more compact,reducing cracks,and revealing the reasons for the optimization of the mechanical properties and low alkalinity of the antifreeze vegetation concrete from a microscopic perspective.This project optimizes the mechanical properties of anti-freeze vegetation concrete,provides technical support for the wider application of frost-resistant vegetation concrete in the northern region,and has certain value and significance for promoting the protection of the ecological environment and helping the construction of ecological civilization in China.