Interface between steel rebar and concrete, studied by electromechanical pull-out testing

The interface between concrete and steel rebar was evaluated by electromechanical pull-out testing, which involved measuring the shear bond strength and contact electrical resistivity of each sample. The bond strength was increased by steel rebar surface treatment (acetone, water, ozone or sand blasting, with ozone being most effective and acetone being least effective), polymer addition to concrete (methylcellulose or latex), increase in water/cement ratio of concrete (particularly from 0.45 to 0.50), and decrease in curing age (particularly from 14 to 7 days). The origins of these effects are rebar cleansing for acetone treatment, rebar surface oxide film formation for water and ozone treatments, rebar surface roughening for sand blasting, polymer interface layer formation for polymer addition, and decreased interfacial void content for water/cement ratio increase and for curing age decrease.