| With the rapid growth of road traffic flow in China,many roads experience damage due to heavy traffic loading,appeared with fissure,protuberance,breakage,fracture and so on.Despite intensive efforts,conventional cement pavement repairing materials is still far from being satisfactory due to poor durability,high investment,large carbon emissions and huge construction difficulty,et al.Therefore,the development of high quality,efficient,cheap and environmental-friendly rapid repairing materials for cement concrete pavement has the vital practical significance.Against the deficiency of existing repairing materials for pavement world widely combined with the present situation of heavy traffic road,it is urgently needed to seek pavement repairing materials with fast setting,high strength and durable performance.Based on the characteristics of geopolymer repair materials,this thesis establishes a three-dimensional structural development model of rapid solidification and high-early-intensity geopolymers through the study of the dynamic characteristics of early hydration characteristics of slag-based geopolymers,and revealed the development characteristics of microstructure over time in the early polymer system.Meanwhile,the mix ratio was optimized,and the development rules of the mechanical properties of the geopolymer repair material were explored.Finally,the microstructure characteristics of geopolymer repair materials were in-depth analyzed via evaluation of the structural characterization and durability performance.This combination assures the impact of material composition and structure on durability performance.The slag-based geopolymer road surface repair materials prepared in this thesis has high strength in early stage,rapid hardening,high interfacial bond strength between old and new materials and excellent durability,which has practical guidance for rapid repair and early opening of traffic on heavy traffic roads.This research achievement,on the one hand,is expected to solve the repairing technology problem in heavy traffic load.On the other hand,it provides new approach for the comprehensive utilization of solid waste for domestic and overseas.The thesis mainly carried out the following six aspects:1.Through the adjustment of the mix ratio,the early work performance of the slag-based geopolymeric polymer paste repair material can be controlled,the fluidity is controlled at 0-198 mm,the initial setting time is controlled at 25-191 min,and the final setting time is controlled at 45-267 min.Combining with the law of ultrasonic wave velocity change over time during the early hydration process of the slag base polymer system,the law of hydration heat release rate over time,the early hydration process of the system is analyzed and studied,and finally the slag-based geopolymer system stimulated by the water glass is finally developed.The hydration process is divided into four stages:(1)initial hydration period,(2)hydration induction period,(3)hydration acceleration period,(4)hydration stability period.2.Based on the advantages of the HYMOSTRUC system,the three-dimensional structure of the slag-based geopolymer slurry was simulated.Simulations show that as the reaction time increases,the raw material particles gradually dissolve,the reaction products increase and fill in the original pores,and the products interweave.A network structure emerged and the geopolymer slurry gradually densified.Through analysis of simulation results,it was found that the introduction of metakaolin,rice husk ash,and silica fume only had a significant effect in the early stage of hydration,and promoted the development of strength.There was no significant difference in the effect of hydration for a long time,and the order of promotion effect was: metakaolin,rice hull ash,silica fume.The introduction of metakaolin and limestone powder also has a significant effect in the early stage of hydration,which promotes rapid condensation and high-intensity development,and the combination of metakaolin and limestone powder has the best effect.3.The mechanical properties of slag-based geopolymeric polymer pastes varied with different mix ratios.The compressive strength for 3 days ranged from 8.37 to 52.6 MPa,the compressive strength at 7 days was between 14.13 and 58.76 MPa,and the compressive strength at 28 days was between 32.19 and 86.35 MPa.The application of the material in the actual project determines the ratio of water to solid is 0.32,the amount of alkali activator is 014,the replacement rate of fly ash is 0.4,and the mix ratio of water glass module is 0.12,the slag-based geopolymeric polymer paste prepared by the blending ratio was 186 mm,the initial setting time was 60 min,the final setting time was 80 min,and the compressive strengths at 3 d,7 d,and 28 d were 53.48 MPa,58.76 MPa,and 86.35 MPa respectively.Compared with the existing cement-based pavement materials,the compressive strength of slag-based geopolymer pavement repair materials 3 d,7 d,and 28 d was increased by about 3 MPa,5 MPa,and 11 MPa respectively.4.Based on the simulation of the hydration microstructure of slag-based geopolymeric pulp and the prediction of performance optimization,the addition of rice husk ash,silica fume and metakaolin modify the slag-based geopolymeric polymer pulp.The results showed that the composites with 10% rice hull ash and 10% metakaolin had the best modification effect on slag-based geopolymers,and the compressive strength at 3 d,7 d,and 28 d increased by 8.48 MPa,9.09 MPa,and 11.75 MPa respectively.5.Based on the simulation of the hydration microstructure of slag-based geopolymeric polymer paste and the prediction of performance optimization,blending metakaolin and limestone to modify the slag-based geopolymeric concrete,and different amounts of slag-based geopolymeric concrete,the effect of durability performance was studied.The results showed that when the content of metakaolin was 15% and the limestone powder content was 5%,the performance was the best,and the compressive strength at 3 d,7 d,and 28 d increased by 7.6 MPa,6.8 MPa,and 7.4 MPa respectively.The addition of metakaolin and limestone powder enhances the durability of slag-based geopolymer concrete.This is due to the high activity of metakaolin and the filling of limestone powder to enhance the compactness of the concrete,optimize the interfacial transition zone,and contribute to strength.The development and durability can be improved,but due to the strong water absorption of metakaolin,the work performance of concrete is greatly reduced,resulting in poor homogeneity of the mixture and more porosity,resulting in a certain degree of strength reduction,and the amount of metakaolin should not exceed the amount 15%.6.The three-dimensional structure simulation results are consistent with the experimental results,which verifies the reliability of the three-dimensional simulation and the rationality of the composition design.The advantages of metakaolin,limestone powder,silica fume,and rice hull ash modification are fully reflected,which are mainly based on the high activity of metakaolin and the compact filling of fine particles. |
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