EXPERIMENTAL STUDY ON ADDITION OF ORGANIC ADDITIVES IN LIME MORTAR

Abstract

Lime has been crucial part of early construction works, used for centuries. Old structures made with lime as mortar has shown exceptional performance in their lifetime, however despite these structures showing their exceptional behaviour in terms of durability and performance, these structures have also gone through many distresses, and some of them need repair and restoration. Durability is one of the most significant parameters of old masonry structures. It has been witnessed that organic additives present in the old mortars have enhanced the properties of these mortars. In India, historical structures have been built using animal and plant extracts as an additive.Therefore, understanding the behaviour of these additives and their impact on the durability of the mortar is required. Unfortunately, the physical and mechanical properties of organic based lime mortar are not documented and need more research emphasis. The amount in which these organic additives are added to shows better result is yet to be determined. There is very less study on the bond strength of the organic additives-based lime mortar. Although lime has shown incredible behavior in terms of durability but there is few research related to the durability criteria of the lime mortar and organic additive based lime mortar. This study suggests the possible interaction of organics like jute, jaggery, and egg with lime, to simulate the mortar used in old structures. Jaggery has been added after its fermentation in 10%, 12.5%, and 15% percentages. Raw jute fibre has v | P a g e been used after chopping and incorporated in three different percentages i.e., 1%, 1.5%, and 2%, and percentages for egg are as 4%, 6%, 8%. Physical properties of these mortars are evaluated using tests like water absorption, workability etc., while for mechanical properties compressive strength and split tensile testing has been performed. Results reveal that mortar with jaggery as additive performs better in compression, jute based mortar has the best tensile strength, and egg based mortar has the least water affinity. Optimum percentage of additive is evaluated here and then it is used to study other engineering properties like durability and bond strength. To determine the durability properties of these organic-based lime mortars, carbonation depth test, acid attack, alkali attack, and wetting and drying tests have been performed. Further, the bond strength of these organic lime mortar in brick masonry has been examined by performing a triplet test. According to the sulphuric acid attack test, the lime mortar with jute as an additive has shown the best results with only a 5% loss in strength which is 23% in standard lime mortar. In the alkali resistance test also, jute has shown exceptional behaviour with a strength loss of 1.5% which is 22% in standard lime mortar. In the triplet test, the shear bond strength of jaggery based mortar in brick masonry is 27.77% higher than the standard lime mortar, hence showing the best result in the shear bond test.