| In recent years,the acceleration of urbanization in China has led to the doubling of solid waste output,which has led to serious waste of resources and environmental pollution.Therefore,the reasonable utilization of construction solid waste is imminent,among which the brick concrete particles with less impurities after crushing and shaping can be considered to be used as the road base or bottom layer in the form of coarse aggregate.However,due to its low strength,low density and high water absorption,it must be strengthened to meet the corresponding technical requirements.Based on the scientific and technological innovation project of Shandong Transportation Department"Research on Key Technologies of recycled aggregate used in road base"(2018b02-01).Based on the comparative analysis of the strengthening mechanism of the coarse aggregate,water glass,silicon resin,silane coupling agent and titanium gypsum slag were selected as the main strengthening materials,and the negative pressure method was proposed to enhance the degree of the opening pores on the surface of the brick concrete particles,and the change rule of the key indexes after strengthening was analyzed in depth;In this study,to improve the degree of filling in the open pores on the aggregate surface,the saturation of filling is proposed as the evaluation index,and through the micro scanning analysis of the particles before and after strengthening by industrial CT,the influence rule of different materials and negative pressure sizes on the saturation of filling is obtained.On this basis,the recycled brick concrete particles are used as coarse aggregate to design the gradation of cement stabilized macadam,and the mechanical properties and durability indexes of the mixture are tested and analyzed from the macro perspective.After strengthening brick and concrete particles with negative pressure,the improvement effects of various materials are different,among which the particle properties of silicone resin are significantly improved,and the crushing value is26.2%.water absorption is 6.5%The apparent density of aggregate is 2.687g/cm~3,less reinforced 2.567g/cm~3improved 4.7%;The crushing value reaches to 27.6%,water absorption reduced to 6.6%,apparent density increased to 2.682g/cm~3,also improved4.5%;The results show that the saturation of silicone resin is 41.2%,the saturation of titanium gypsum slag is 38.3%,and the effect of the other two materials is not good.Considering the performance improvement and economic cost,the titanium gypsum slag can be used as the preferred material for strengthening recycled brick-concrete coarse aggregate.Based on the analysis of the test results of cement stabilized macadam,it is found that the unconfined compressive strength of 7days is 3.8MPa,the representative value of 90days is 5.6MPa,and the latter is 38.5%higher than that of the unreinforced;The cleavage strength at 7days is 0.40MPa,which is higher than that without strengthening 36.7%;After strengthening,the cleavage strength at 90days is 0.60MPa,bending tensile strength is 0.91MPa,the dynamic resilience modulus is 13702MPa,the fatigue life under the 0.4 stress intensity ratio is 620000 times,which has been improved significantly.The erosion loss of the strengthened specimen is 0.206%,reduced 17.5%,the strength ratio after freezing and thawing is 90.60%,higher than when not reinforced 5.1%.By comparing the change laws and improvement effects of various properties.The brick concrete particles strengthened by titanium gypsum slag material and negative pressure can be used in cement stabilized base in the form of coarse aggregate,and have good road performance.It can also digest the factory waste,turn waste into treasure,and have a broad application prospect. |
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