Accelerating the Hardening of Lime Mortar on Addition of Organics for Repair in Heritage Structures

Abstract

Repair and restoration of heritage structures have become important as they are the evidence of cultural and historical significance. Strength and durability of lime mortar makes it a good repair material for achieving movement with the old mortar and therefore compatible. Hardening of lime mortar may take centuries to complete and therefore accelerating the hardening process helps in achieving the desired strength earlier. This work aims at studying the impact of organic addition on the physical, mechanical, chemical and durability properties of hydraulic lime mortar to accelerate the hardening. A comparative study of lime mortars with addition of three different organics namely Vitis vinifera (Raisins), Vita vinifera (Zante currant) and Phoenix dactylifera (Dates) were performed. The lime mortar was prepared with binder to aggregate ratio of 1:3, water to binder ratio of 0.75 and with addition of organics in various concentrations (0, 2, 4 and 6%). Bulk density, porosity and water absorption were the physical properties analyzed. The compressive strength was determined for the specimens. The rate of carbonation was determined through the phenolphthalein test. The mineralogical composition of the mortar was identified by using analytical techniques like XRD and FTIR. Capillary rise test was conducted to study the durability of the lime mortar. It was observed that organic addition to lime mortar has enhanced its properties along with an increase in the rate of carbonation and thereby accelerating the hardening. The carbohydrate rich organic additives increased the CO2 content throughout the mortar. Hence increased the strength and durability of lime mortars used in the repair of heritage structures.