PSI - Issue 71

Dharmadas Bairagi et al. / Procedia Structural Integrity 71 (2025) 417–423

418

1. Introduction Roofing plays a major role in heat gain in building envelope. Conventionally in rural or low-cost houses, Lime terracing, Stone slabs, Thatch roof and GI sheets are being used as roofing materials. These materials have very high thermal transmittance and thus there is a huge heat gain in the building. With the changing climatic conditions this heat gain has become crucial for occupant’s thermal comfort and wellbeing. It is estimated that the frequency, intensity of warm days and warm nights are projected to increase over India in the next decades, while that of cold days and cold nights will decrease (Sanjay, J. et al., 2020). The increased heat gains result in increased demand for cooling energy. One approach to reduce energy use in buildings is to improve the insulation properties of roofing assembly (Asdrubali F., 2015). Roof insulation can be over deck or under deck. Commercially available under deck insulating materials are synthetic materials from polymers such as polystyrene, mineral or glass wool have been used as high quality thermal insulation for building envelopes (Korjenic, A, 2016; Abdou, A. and Budaiwi, I., 2013). Natural fibres such as cellulosic materials, wood fibers, flax, hemp, bamboo, cotton, and recycled paper, available from agricultural and forestry waste present a good alternative as bio-insulation materials. India is very rich in bamboo cultivation; it is observed that large amount of bamboo biomass is generated in different operations of bamboo processing. According to operational guidelines of National Bamboo mission, 2019, India has the highest area (13.96 million ha) under bamboo and is the second richest country, after China, in terms of bamboo diversity with 136 species. During the processing and product manufacturing with bamboo, more than 30% of the bamboo like branches, nodes, lower portion of the culm, etc. are left unused and wasted. Cetiner, I., and Shea, A. D. (2018) explored potential of insulation materials based on wood-derived wastes and concluded that even though thermal conductivity of wood based material is higher than inorganic based materials, they present a lower cost option. Boussaba, L et. al. (2018) explored the properties of coconut fat waste with clay matrix and natural fibers as phase change materials for thermal energy storage. It was found to increase thermal inertia of building envelop when sandwiched between thin stainless steel sheets. Similar observations were recorded by Wi, S et.al. (2015) using fatty acid ester and exfoliated graphite Nano platelets. From the literature it is understood that thermal conductivity is a critical characteristic used frequently to assess the insulation capacity of the material in a building (Kumar, D, 2020). Thermal conductivity decreases with increase in particle size, pores and voids present in the material. Density and water absorption have a positive effect on the thermal conductivity performance of bio-based materials (Toledo Filho, 2020). Nguyen et.al. (2018) developed six different types of insulation boards by varying the dosages of bamboo powder with using bone glue, nerve glue, and sodium lingo-sulphonate as binders. They reported that the thermal conductivity of fiberboards ranged from 0.101 to 0.201 W/mK with longer fiberboards having lower values because of their lowest compactness. They also reported that the most ideal conditions for the growth of mold and algae as 2 weeks at 30 o C and 84% RH. Insulation materials based on bamboo and other wood-derived wastes have been proven to offer enhanced thermal comfort along with decent mechanical properties. It was found that the thermal conductivity as well as mechanical performance in terms of flexural and compressive strength decreases with an increase in the fiber content and size (Mnasri F. et. al (2020); Rabbat C et. al (2022); H. Li et. al (2023)) The insulating material in question must possess essential properties like low thermal conductivity, high mechanical strength, acoustic, low water retention capacity, techno-economic feasibility, etc., as these properties will directly affect the energy efficiency and economics of the building. Therefore, the most studied parameters by researchers were thermal performance, density, compressive strength and water absorption capacity, and bio insulation properties (Ali ME et al, 2017). In the present study bio-fiber based insulating panels were manufactured and physical, mechanical, and thermal properties were investigated. Lime, soil, and Calcium sulphate hemihydrate (PoP) were used as binders and Bamboo waste fibers are used as filler. Coconut Coir and Bamboo Mesh were used as reinforcement material.