Bond behavior of steel bars embedded in concretes made with natural lightweight aggregates

The bond properties of reinforcing steel bars embedded in structural concrete made with locally available natural lightweight aggregates, was studied using pull-out tests on cubic specimens of 150 × 150 × 150 mm. A series of 30 specimens were cast considering the effect of bar diameter, and concrete compressive strength. Test results showed that the load-slip behavior of the structural lightweight concretes (SLWCs) investigated compare reasonably well with the behavior of concretes reported in the literature, and is dependent upon the compressive strength, bar size and the embedded length. The bond strength of SLWCs increased with a higher concrete compression strength but decreased as the bar diameter was increased. Comparisons of measured bond strength with the ACI bond equations showed that for all cases the experimental bond strength values were higher than the design ones. However, the results indicate use of caution when applying bond formulas of normal weight concrete to lightweight concretes. Furthermore, this study has revealed that locally available natural lightweight aggregates could be considered as a promising, and cost effective material for designing reinforced concrete members.