Mechanical properties and corrosion of CAC mortars with carbon fibers

The changes in mechanical properties of Calcium Aluminate Cement (CAC) mortars due to the addition of carbon fibers (CFs) to the mix have been studied. Compressive and flexural strengths have been determined in relation to the amount of CF added to the mix, water/cement ratio (w/c), curing time and porosity. The relationship between the values of ultrasonic pulse velocity (UPV) and compressive strengths for CAC mortars have also been obtained. Additionally the corrosion level of reinforcing steel bars embedded in CAC mortars containing CF and silica fume (SF) has also been investigated. The proportion of CF and SF in the mix, the w/(c + SF) ratio and the type of aggressive media have been chosen as test parameters. The study demonstrates that the addition of small amounts of CF to the mix increases significantly the mortar strength, but at the same time reduces its resistivity and the steel protection capacity, increasing porosity.

► The highest Rc has been obtained for a 0.5% of CF in CAC mortars.
► The increase of CF from 0.5% to 5% does not provide a significant increase in Rc.
► CF increases the corrosion rate of steel in CAC mortars with or without SF.
► The higher is the CF content, the higher is the mortar cover porosity.
► SF does not fully counteract the negative effect of CF in corrosion rate values.