Study On Preparation And Performance Of Geopolymer/Emulsified Asphalt Composite Repair Mortar

In 2019,China's highway freight volume will exceed 40 billion tons.Under such a large load,roads will inevitably cause damage,and if not repaired in time,it will cause serious damage.Common cement-based repair materials have low cost but poor adhesion,long curing time,and large pollution;organic repair materials have good adhesion and fast setting time,but are costly and easy to age.In the context of advocating energy saving and emission reduction,and reducing energy consumption,it is urgent to develop low-cost,green and environmentally-friendly road surface repair materials.In this paper,slag and fly ash were used as the main raw material,geopolymer-based repairing material is prepared under the action of an alkaline activator.Water glass and Na OH were used as activators to investigate the influence of water glass modulus and water glass content on the mechanical properties of geopolymer-based repair materials and the development of condensation and hardening.Emulsified asphalt and silica fume modified geopolymer repair mortar;study the repair performance and durability of geopolymer/emulsified asphalt composite repair mortar(GA composite mortar for short).Finally,the early hydration dynamics of GA composite mortar was studied and the microstructure characteristics of GA composite mortar were investigated through SEM,IR and other micro tests.The results showed that the strength and setting time of geopolymer repair mortar can be effectively adjusted by adjusting the water glass modulus and the amount of water glass.1d compressive strength 18.4MPa?29.1MPa,setting time 13min?38min.However,it still cannot satisfy 1d compressive strength> 20 MPa,30min <setting time <50min.The results of orthogonal optimization study of modified GA composite mortar show that the most important factor for 1d compressive strength of GA composite mortar is the water glass modulus,followed by the amount of silica fume;and the factor that has the greatest effect on the setting time is the amount of emulsified asphalt.Therefore,the 1d compressive strength of GA composite mortar can be improved by adjusting the water glass modulus,the setting time of GA composite mortar can be extended by increasing the amount of emulsifiedasphalt,and the problem of strength reduction caused by emulsified asphalt can be improved by silica fume.When 10% emulsified asphalt is added,the setting time of GA composite mortar is extended by 3 times;when 5% silica fume is added,the 1d compressive strength is increased by 18.1%.The modified GA composite mortar has a compressive strength of20 MPa ? 29 MPa and a setting time of 30 min ? 43 min.The compressive strength and setting time can meet the requirements of repairing materials at the same time.GA composite mortar repair performance and durability research results showed that the bond strength of GA composite mortar can reach 2 MPa at 28 days,and the shrinkage of 28 days is only 0.036%;the results of durability research show that after 20 freeze-thaw cycles,the mass loss of GA composite mortar is only 0.18%,and the loss of compressive strength does not exceed 4%;after thermal oxygen aging,the compressive strength of GA composite mortar increased by 4.9%.According to SEM analysis,it was found that emulsified asphalt can introduce a large number of small air bubbles in the GA composite mortar,and the more porous the emulsified asphalt,the more the number and the pore volume increase;microcalorimeter test results showed that emulsified asphalt can delay the hydration of geopolymers;observation results of polarized light microscopy showed that as the hydration process advances,the bond between the emulsified asphalt and the geopolymer becomes closer.