| Diseases such as broken plates,staggered platforms,and mud in cement concrete pavement are mostly caused by voids at the bottom of the pavement.Grouting treatment has been widely used as an important method to improve the voiding of the bottom of cement concrete pavement.However,as the road continues to serve,the repeated loading of driving loads will cause the road structure to lose air again after the treatment,that is,the weakening of the grouting material at the bottom of the board.At present,the research focus of scholars at home and abroad is more on the mix ratio of grouting materials and the construction technology of grouting.Few analysis and research on the weakening behavior of grouting materials on the bottom of cement concrete slabs.Therefore,the analysis of the weakening behavior of the grouting material on the bottom of the cement concrete has research significance and application value for filling the phenomenon of void treatment at the bottom of the slab.In this paper,three types of grouting materials are selected as test objects,including fly ash inorganic grouting materials,emulsified asphalt type organic grouting materials,and the innovative use of steel slag powder as cement grouting materials material.Then,the internal cause weakening behavior analysis is performed on the grouting material,that is,the material property weakening analysis test.In order to study the weakening behavior of the grouting material at the bottom of the plate,the weakening behavior of the three grouting materials under single adverse factors was analyzed,and the microscopic mechanism of the weakening behavior of the grouting material based on adverse conditions was analyzed using SEM scanning electron microscopy.analysis.Finally,in order to find a comprehensive evaluation index and evaluation method for the weakening behavior of the grouting material,the principal component analysis method was used to correlate the weakening behavior of the grouting material based on the synergistic effect of the freeze-thaw cycle and the dynamic water scour.The comprehensive principal component was used as the evaluation index of the weakening behavior of the grouting material,and a mathematical model of the weakening behavior was established.The main conclusions are as follows:(1)In order to use resources reasonably,this article uses steel slag powder as an admixture to prepare grouting materials,and the 30%admixture is the best admixture through experiments.And continue to choose the two most typical grouting materials-fly ash type grouting material and emulsified asphalt type grouting material,a total of three materials as the research object.In order to meet the actual construction requirements,the fluidity,compressive strength and dry shrinkage tests were carried out in sequence.The fluidity test included the fluidity in both horizontal and vertical directions,and was collectively referred to as the irrigability of the grouting material..It can be seen from the test that the three materials meet the requirements,and the dry shrinkage of emulsified asphalt-based materials is better than that of the other two inorganic grouting materials.In terms of compressive strength:fly ash>steel slag powder>emulsified asphalt.(2)The self-braking water erosion tester has carried out research on the water erosion resistance of the three materials.It can be seen that with the increase of the frequency of dynamic water erosion,the volume shrinkage rate of the material at the early age shows a W-shaped change,which It is because the hydration reaction in the early materials is relatively active.After contact with water,the early hydration activity increases,the hydration reaction product increases,and the rate of volume increase is greater than the volume loss;at the same time,it is known that the inorganic grouting material at the same age The volume increase is about 1.5 to 2 times that of bituminous grouting materials.In order to evaluate the frost resistance performance of the grouting material,the salt damage freeze-thaw test was carried out on the three grouting materials.The test variables were:curing age,sodium chloride concentration,freeze-thaw temperature,mass loss rate and strength loss rate.Using the Pearson correlation analysis,it is concluded that with the continuous increase of the aging period and the number of freeze-thaw cycles,the mass loss and strength loss continue to accumulate.According to a comprehensive comparison,the order of affecting the degree of frost resistance of the three grouting materials is as follows:age>sodium chloride concentration>freeze-thaw temperature,and it also indicates that external adverse factors have the greatest influence on the frost resistance of the grouting material.Comparing the three materials with each other,it is found that the concentration of sodium chloride has the greatest influence on the emulsified asphalt grouting material,and the curing period and freeze-thaw temperature have a more obvious influence on the two inorganic grouting materials.(3)Using the SEM electron microscope scanning test,the weakening behavior of the three grouting materials under the action of dynamic water scouring and salt damage freeze-thaw was analyzed from a microscopic level.According to the scanning imaging,it can be known that due to the special lattice structure of the steel slag powder itself The tolerability under dynamic water scouring is not as good as its own weakening behavior under low-temperature salt damage and freeze-thaw conditions.That is,the dynamic water scouring effect is more unfavorable for steel slag powder grouting materials;it is also due to the material properties of emulsified asphalt.The ability of emulsified bituminous materials to resist freezing and thawing at low temperature is weak,and it is found that the internal pores of the material increase significantly during the weakening process.(4)In order to simulate the weakening behavior in line with the actual situation,this paper couples the two adverse factors of dynamic water scouring and low temperature freeze-thaw,which act on the grouting material,and control the independent variables as the frequency of scouring,freeze-thaw temperature,freeze-thaw The number of cycles depends on the mass loss rate,strength loss rate and volume loss rate.There is no independent existence of the six test variables,and there is a correlation between the two.In order to eliminate the overlapping effect of the two variables,a comprehensive evaluation index for the weakening behavior of the grouting material is found.Therefore,this paper adopts the principal component analysis method to establish the evaluation model of the pressure drop material weakening behavior under the coupling effect of freeze-thaw cycle and dynamic water scouring.By extracting the principal component,the original data is substituted into the model to obtain the principal component score value.This reflects the degree of weakening behavior under the principal component.The comprehensive evaluation index of weakening behavior of grouting material is proposed,and the corresponding evaluation mathematical model is established as:χi=ξ1X1+ξ2X2+…+ξiXiThe advantage of this model is that no matter how many kinds of variables continue to be added,as long as there is a correlation between the variables,then this method can be used to quickly and easily obtain a comprehensive weakening evaluation score,according to the size of the score,you can judge the weakening of the material The degree has a certain role in recommending the rationality of grouting materials in the application of preventive maintenance in actual engineering.(5)Through test verification,it is recommended to use fly ash type grouting material and steel slag powder grouting material in the section where the bottom of the road slab is emptied more seriously,and it is located in the saline area or the area with low natural environment temperature;Evacuation is not serious,and it is recommended to use emulsified asphalt organic grouting materials in rainy areas;... |
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