Robert Degeimbre

Durability of mortars modified with metakaolin

Abstract Results of an investigation to determine the effects of metakaolin additions on transport properties of mortars are reported. Comparisons are made to ordinary Portland cement (OPC) to determine the influence of addition and replacement percentage. Cement is replaced on a mass basis of 5–20% for metakaolin. A mixture with natural kaolin is also studied. The transport properties and chemical behaviors are analyzed by means of chloride diffusion tests and sulfate immersion. Observations after more than 100 days are used to prescribe mixtures that reduce the rate of chloride diffusion and sulfate degradation. For metakaolin, the optimum seems to be between 10% and 15% with regard to inhibition effect on chloride diffusion and sulfate attack.

Effects of Environment on Repair Materials: Results of a Five-Year Research Project

Research was conducted to analyze the behavior of more than 20 repair systems, including a wide range of coatings and products. Based on polymer mortar, polymer modified cementitious mortar, and cementitious mortar, the repair systems were applied to different concrete substrates in order to analyze the adhesion and durability. Several aging factors were investigated such as wet/dry cycles, solar radiation, and freeze-thaw cycles. New test methods are described that were developed in order to simulate site conditions to the extent possible and are compared with natural aging when possible. Wider study is devoted to analysis of the effects of water itself, which is most likely the first cause of alteration of adhesion between concrete and repair systems. All these forms of aging are compared and technical recommendations are proposed.