Experimental study on bonding strength between high-strength bolt and cement-based grouting material

Abstract

This study investigated the bonding strength between various cement-based grouting materials (CBGM) and high-strength bolts, the flexural and compressive strength variation of different CBGM with curing age, and the failure characteristics of flexural, compressive and bonding strengths. Moreover, the morphological characteristics of bond-slip curves and their similarities and differences were discussed as well. Based on the mechanical property and safety analysis, a calculation model of the critical anchorage length of high-strength bolt in CBGM was proposed. The results indicate that the flexural and compressive strengths increase with the increase of curing age. The strength growth rate is faster at the initial stage of 3 days, which implies that the CBGM has a significant high-early strength characteristic. Depending on the diameter and type of high-strength bolts employed, the bonding strength of specimens can be divided into two failure forms, i.e., splitting and slipping pull-out. The specimens with threaded bolts easily take place a splitting failure form, but the specimens with plain round bolts tend to be destroyed with a slipping pull-out failure form. The ascending section of bond-slip curve is well fitted with the same stage of CEB-FIP 2010. However, a linear relationship can be employed to characterize the bonding strength between CBGM and high-strength bolt. The bond failure capacity is also linear correlation with the strength of CBGM.