Development of grouts for consolidation of old renders

Abstract

A study was conducted on the development of lime based grouts for consolidation of renders and plasters detached from the support. The aim is to develop grouts that should be compatible with the pre-existing materials and allow the restoring of the adherence of coatings to the background. Special attention was paid to the rheological behaviour of the grouts and to other features of the fresh state. The role of components such as binders, aggregates and admixtures used in the formulations was tested through an outlined series of mechanical and physical tests. In terms of hardened state properties, a set of basic requirements (related to strength and capillarity) were evaluated and a test for adhesion loss measurement was developed in order to test the ability of developed grouts to restore adhesion of coating layers.The rheological behaviour was evaluated through a distinct procedure, which involved the test with a specific speed profile (dwell profile). The dwell profile allows studying the rheological behaviour along measuring time, making possible to observe changes in rheological parameters in mortar suspensions, through the measurement of flow curves along the time test. The dwell profile allowed obtaining the rheological parameters (viscosity and yield stress) according to the Bingham model.Grouts based on lime, fine sand and metakaolin together with the right amount of water and admixtures were developed and adjusted in order to be used in consolidation works of old renders.