Preparation and engineering properties of low-viscosity epoxy grouting materials modified with silicone for microcrack repair

Abstract Microcracks are common in the cast-in-situ concrete pavement of the bridge deck, DDMS was selected as modifier, AD- I, AD- II and AD- III active diluents were used as viscosity reducers to effectively repair the cracks. And the preparation process of low-viscosity epoxy grouting materials modified by silicone was optimized. Then the working properties (viscosity, gelation time and groutability) and mechanical properties of silicone modified low-viscosity epoxy grouting materials were clarified. Finally, the evolution law of mechanical properties of low-viscosity epoxy grouting material modified by silicone under high temperature impact, temperature change cycle and freeze–thaw cycle was revealed. The results show that the physical and mechanical properties of grouting material prepared under the conditions of reaction temperature 100 °C, reaction time 3 h and DDMS content 11% were the best. The repair depth of low-viscosity epoxy grouting material modified with silicone in 0.5 mm wide crack exceeded 10 cm within 5 min at 25 °C. But its gel time was longer, up to 24 ~ 28 h. After curing for 3 days, the shear strength and bond strength of the silicone modified low-viscosity epoxy grouting material under room temperature reached more than 90%, and its high-temperature shear strength and bond strength reached 70%~90%. Compared with EP grouting material, the low-temperature and normal-temperature impact toughness of the grouting material after adding diluent and DDMS increased by 57%~71% and 31%~48%, respectively. After high-temperature impact, temperature change cycle and freeze–thaw cycle, the mechanical properties of silicone modified low-viscosity epoxy grouting material decreased slightly, but it was still stronger than EP grouting material. Its tensile strength was still higher than 30 MPa, elongation at break was higher than 5.0%, and bond strength was higher than 3.0 MPa.