Microstructure characterizations, thermal analysis, and compression stress-strain behavior of lime-based plaster

Classical lime-based plasters (LP) are multilayer complex systems made of different fillers and binders; the behavior of LPs is determined by their physical properties: mutual connection, contact with the substrates, and external factors. Lime plaster is set to a solid mass that is durable and relatively flexible. It is permeable and allows for moisture diffusion and evaporation. It is less affected by water and will not dry or dissolve like clay or gypsum plaster. Plasters of hydrated lime are less brittle and less prone to breakage, which do not require expansion joints. Different plasters have been used in construction industries, such as cement, lime, mud, stucco, and gypsum plasters. Lime-based plaster (LP) is used as building insulation materials (Bims) against environmental impacts. Lime plaster is made of sand, water, and lime, usually non-hydraulic hydrated lime (also known as slaked lime, high calcium lime, or air lime). Ancient lime plaster often contained horse hair for reinforcement and pozzolanic additives to reduce work time. Microstructure tests such as X-ray fluorescence (XRF), energy dispersive X-ray (EDX), X-ray diffraction, scanning electron microscopy, and differential scanning calorimetry were used to identify the LP. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy, compressive strength, and modulus of elasticity. The XRF and EDX study revealed that the LP was mainly composed of SiO2 and CaO, predominantly changed into calcium-silicate and CaCO3 throughout the carbonation process. TGA results showed that the LP had high thermal stability up to 150 degrees C and 16.6 % weight loss at 1000 degrees C, proving the significant heat capacity of the material and fire resistance. The compressive strength of the LP with water to binder ratio (w/b) of 0.75 and 0.9 were 900 and 350 kPa at 28 days of curing, respectively. Three distinct mathematical models, including beta, rational, and Vipulanandan p-q models, were proposed to predict stress-strain relationships of the LP. Based on the statistical parameters such as coefficient of determination (R-2), root mean square error (RMSE), and mean absolute error (MAE), the Vipulanandan p-q model was the best model for predicting the stress-strain behavior of the LP.

Automated summary

Classical lime-based plasters are complex systems made of different materials, which have good physical properties and can be used as building insulation materials. Various tests and models were used to analyze the composition and behavior of lime-based plasters.