Evaluation of repair effect of patch repair materials containing fly ash and lithium nitrite

Abstract

As a conventional repair method for reinforced concrete (RC) structures deteriorated by the chloride attack, the patch repair has been applied widely. When the patch repair method is applied, the re-deterioration has been sometimes observed around the joint part of the substrate concrete and the repair material. One of the major deterioration mechanisms after the patch repair is the macro-cell corrosion caused by the remained chlorides in concrete or by the corrosive products like chloride ions (Cl-) supplied through the inadequate joint part. In this study, the effects of fly-ash-mixing and the dosage of LiNO2 in the patch repair materials on the basic properties of repair materials and on the chloride-induced steel corrosion due to the supply of Cl- ions around the interface between the substrate concrete and the repair material were investigated. As a result, the effective diffusion coefficients of Cl- obtained by using the joint specimens with polymer cement mortar (PCM) were larger than the cases of joint specimens with normal mortar. The PCM based patch repair materials showed the high resistance to Cl- penetration but in some cases, Cl- penetration into concrete near the joint surface between concrete and patch repair materials was promoted. On the other hand, the PCM containing both fly ash and LiNO2 showed a high protection effect against steel corrosion in the RC joint specimens and the macro-cell current around the joint face was also suppressed compared with the case of a general PCM.