Evaluation on feasibility of fly ash cement mortar as adhesive of post-installed rebar

This study evaluates the feasibility of using fly ash cement mortar as the substitute of commercial anchorage adhesives by means of experimental tests. Temperature effect is also investigated. Different amounts of fly ash are added in the cement mortar and the mortars are mixed according to the proportion design methods illustrated in the literature. In addition, silica sand is used instead of river sand in some mortar. By summarizing the results of flow test, compression test, and fire resistance test of the mortar specimens, three better mixture proportions are determined. The pull-out specimens were prepared by implanting #3 (D10) steel bars into concrete cylinders to a depth of 9 cm. The specimens for temperature effect tests are heated and kept in furnace under 400°C or 600°C for 60 minutes and cooled naturally before conducting experimental tests. The feasibility assessment is carried out by comparing the pull-out test results of this study with those of rebars installed with commercial adhesives from earlier study. The results have shown that rebars installed with the proposed cement mortar may achieve acceptable bonding effect, although the bonding strength at room temperature is lower than those of commercial adhesives-installed rebars.