With the continuous acceleration of urbanization process and infrastructure construction,a large amount of construction solid waste is generated.Due to the structures of demolished buildings are mostly brick-concrete,clay bricks account for a relatively high proportion of construction solid waste.In this paper,waste clay bricks were used to produce recycled fillers and replaced natural fillers for municipal road projects.After determining the gradation through the molding study,the road performance of the recycled fillers and the reaction mechanism of lime-stabilized recycled fillers were studied,and the performance of recycled fillers were also tested through testing road.Then based on life cycle assessment,the environment impacts and economic benefit of recycled fillers used in municipal road were quantitatively evaluated.The results show that the California bearing ratio of recycled fillers exceeds 150%,while that of the recycled filler with lime exceeds 250%.The compressive strength of lime-stabilized recycled fillers also increases significantly with the increase of curing age,and the compressive strength at 28 d increased by 120% ~ 175% compared with that at 1d.While,the incorporation of lime can also improve the water resistance stability and drying shrinkage performance of the recycled fillers.The lime dosage of lime-stabilized recycled fillers decreases with age,and the cumulative heat release continues to increase.The microscopic morphology shows the particles of recycled fillers with lime interconnect with other,and the structure is denser than that without lime.The above results indicate that the recycled fillers with sintered clay bricks as main component can directly react with lime under the compacted conditions,and obviously improve the performance of the recycled fillers.However,when the lime content is high,the excess lime fails to participate in the reaction,which adversely affects the performance of the recycled fillers such as the California bearing ratio and compressive strength.The optimum lime content of recycled fillers used in this studyd is 3% ~ 4.5%.The test results of testing road show that the compaction of recycled fillers used in roadbed exceeds 95% after rolling 5 times,the California bearing ratio reaches 400 k Pa,and the deflection is less than 1.6mm.As the pozzolanic reaction between clay bricks and lime continues,the strength of type Ⅱ recycled fillers mixed with 3% lime for subbase is significantly improved with the increase of curing age.After curing for 30 days,the bearing capacity of subbase increased by 141.75% compared with that at 1d,and the deflection decreased by73.47%.The performances of recycled fillers used in the subbase and below of municipal roads satisfy the requirements of relevant standards.The results of life cycle assessment show that the application of recycled fillers prepared with waste clay brick in municipal road has a significant influence in terms of global warming,acidification and solid waste.Compared with the application of cement-stabilized gravel and lime-stabilized soil,the application of 1t lime-stabilized recycled fillers on subbase can obtain an environmental benefit of 10.136 yuan and save costs of 70.588 yuan.While,the application of 1t recycled fillers on roadbed can obtain an environmental benefit of 7.396 yuan and increase costs of 29.539 yuan.The production or purchase cost of fillers and transportation distance are the key factors of environmental benefits and construction costs.Therefore,the environmental impacts and construction costs of recycling of construction solid waste can be reduced by reasonable planning the location of recycling plant to reduce the transport distance,and choose fixed or mobile production equipment according to the actual situation. |