Studies on Polymer-Modified Lime-Surkhi Repair Mortar for Heritage Buildings: Physico-Mechanical and Micro-Structural Characterization

Abstract

AbstractLime-surkhi repair mortars modified with water soluble polymer, i.e. Hydroxypropyl methylcellulose (HPMC) admixture and Polypropylene (PP) fibre, were developed and further studied to obtain repair mortars for heritage restoration application. As water permeability of lime-surkhi mortar was closely related to the strength and durability of heritage structures. Therefore, the objective of this paper was to examine the relationship between microstructural and mechanical properties of lime-surkhi mortars in order to optimize their properties for a more efficient use in heritage buildings. In this study, for determining the lime-surkhi-HPMC interaction with PP fibre, the samples of different mix proportion was prepared by incorporating HPMC ranging from 0 to 2.0% and PP fibre from 0 to 1.0%. Then water permeability, mechanical and micro-structural properties were investigated. The test result showed that 28 days compressive strength of mix with 2% HPMC and 0.5% PP fibre provided the desirable strength of 4.20 MPa with desirable flow value of 122 mm. The various instrumental techniques such as thermo-gravimetric analysis (TGA), scanning electron microscope (SEM) and X-ray diffraction analysis (XRD) were used to evaluate the effect of adding surkhi in lime repair mortar. The results showed that the compressive strength was increased and water permeability was reduced after the addition of surkhi into the repair mortar. Furthermore, the results indicated that as compared to the reference repair mortar; the microstructure of repair mortar was quite improved with PP fibre content of 0.5 weight%, which imparted lower water absorption and higher mechanical strength.KeywordsLime-surkhi repair mortarHeritage buildingsWater soluble polymersPolypropylene fibreWater permeability