Microstructure and chemo-physical characterizations, thermal properties, and modeling of the compression stress-strain behavior of lime-based roof and screed paste

Abstract

The share of buildings in energy consumption and global greenhouse gas emissions is significant. Lime mortars are common in traditional architecture, but due to their mechanical disadvantages compared to cement, they were excluded from modern constructions. It can significantly contribute to environmental sustainability by replacing modified lime mortars with common cement mortars, particularly in the building envelope system. Conventional lime-based roof pastes (LRP) are multilayer complicated systems composed of various ingredients and binders; their physical properties define the function of LRPs: interact connection, underlayer contact, and external variables. Lime pastes sets as a durable and generally flexible solid mass. It is breathable and permits the transfer and evaporation of moisture. It is less susceptible to water and won’t dry or disintegrate, unlike clay or gypsum paste. Pastes made of hydrated lime are less brittle and breakable, and as building insulation materials (Bims), a lime-based paste is used against environmental concerns. Microstructure and material characterization tests, compressive strength, and strain were used to identify, characterize, and evaluate the LRP. The dispersive energy X-ray (EDX) and X-ray fluorescence (XRF) indicated that LRP is composed of two main compounds, SiO2 and CaO, which are primarily converted to calcium silicate and calcium carbonate during the hydration process. The thermogravimetric analysis (TGA) findings demonstrated that the material exhibited high thermal stability up to 200 °C and 11.4% weight loss at 975 °C, demonstrating the high heat capacity of the LRP and fire resistance. At 28 days of curing, the compressive strength of the LRP with water to binder ratio (w/b) of 0.75 and 0.60 was 0.761 and 1.094 MPa, respectively. The stress-strain relationships of the LRP were predicted using three independent mathematical models, including the rational, β, and Vipulanandan p-q models. Based on the coefficient of determination R2 and root mean square error (RMSE), the best model for predicting the compression stress-strain behavior of the LRP at various w/b and curing times was the Vipulanandan p-q model.