Bond performance between surface modified bamboo scrimber bar and bamboo biochar mortar

In order to study the bonding performance of bamboo scrimber bar-bamboo biochar mortar interface, pull-out tests were carried out on 85 bamboo scrimber bar-bamboo biochar mortar specimens. The effects of surface modification methods of bamboo bar, equivalent diameter of bamboo bar, compressive strength of mortar and bond lengths on the bond properties were also taken into consideration. The different bonding failure modes of the pull-out specimens were observed. The bond-slip curve, bonding strength and slippage were obtained. The failure mechanism was analyzed. A bond-slip constitutive model of bamboo scrimber bar-bamboo biochar mortar interface was established, and the effective surface modification method of bamboo scrimber bar was obtained. The results of the study show that there are three failure modes of the specimens under different initial conditions, including mortar splitting failure, bamboo bar tensile failure and bamboo bar pulled-out failure, among which mortar splitting failure is the most common. The failure process can be divided into micro-slip stage, slip stage, descending stage and residual stage. The bonding strength of the mortar interface can be increased by 13-46 times by modifying the surface of the bamboo bar. The interfacial bonding performance decreases with the increase of bonding length and equivalent diameter, and the effect of mortar strength on bonding strength is not obvious. It is recommended to modify the bamboo scrimber bar through the two methods of sticking sand and coating epoxy mortar. On the basis of ensuring bonding performance, it can improve the peeling of water absorption and expansion of bamboo bands during the maintenance process and the problem of the structure failing in advance. According to the experimental bond-slip curve, the bond-slip constitutive model of bamboo scrimber bar-bamboo biochar mortar treated by sticking sand was proposed. The bond-slip constitutive model can accurately predict the bond behavior between bamboo scrimber bar and mortar. After verification, the model is also applicable to the bonding interface destruction in the test under the other modification of bamboo.