Investigation of mechanical, thermal, and acoustic performance of insulation materials containing microwave and ultrasound pretreated coffee wastes and estimation of thermal parameters using artificial neural network

Abstract

As a result of increasing coffee consumption in the world, the amount of coffee waste, which is an important environmental problem, is increasing. Due to their complex organic properties, they should not be discharged to landfills. At the same time, these wastes with a porous and cellulosic structure, have high acoustic and heat insulation performances in the building material they are used. In this study, commercial coffee wastes were evaluated without pre‐treatment (CW) and with microwave (MCW) and ultrasound (UCW) pre‐treatment in insulation plaster containing boron. First, the morphological, thermal, and chemical properties of coffee wastes were determined by SEM, TGA, and FTIR analyzes. CW, MCW, and UCW wastes were replaced with insulation plaster at rates of 10%, 20%, and 30%. The physical, mechanical, thermal, and acoustic properties of insulation plasters produced from coffee waste were determined by the analysis methods given in Turkish Standards. According to the results, insulation plasters obtained from pre‐treated wastes were more efficient in terms of mechanical and thermal properties. In terms of thermal and acoustic insulation, UCW30 insulation plasters showed the best performance. Thermal conductivity values were estimated by entering dosage, density, water absorption, bond strength, compressive strength, and moisture values as input dataset to artificial neural network (ANN). The developed ANN model and the experimentally obtained data were compared and it was observed that the results were in harmony. As a result, with this study, a new generation green insulation material was produced by recycling coffee wastes. In this way, a different solution has been found for an important environmental problem.

Incorporation of Waste in Thermal Mortars—A Literature Review

“…For non-structural elements, La Scalia et al [45] stated that the addition of coffee waste and fly ash in thermal mortars led to suitable values of mechanical properties. In another study with coffee residues, Yildiz et al [58] found that, in general, microwave and ultrasound pre-treated coffee waste additives improved the mechanical properties of mortars compared to raw coffee waste additives. The authors also highlight that pretreatment of raw coffee waste led to an increase in 10% in compressive strength.…”

“…Vegetal wastes: coffee waste a,b (3), cork waste a (3), fallen leaves fibres a,b (3), hemp shives a,c (2), rice husk ash a,b (2), wood waste a,b (2), bagasse ash b (1), desiccated and smashed desiccated platanus acerifolia fruits a (1), chopped cane stalks a (1), almond/hazelnut/nut shells a (1), coconut shells a (1), bean and pea pods a (1), curauá fibres e (1), sunflower plant bark and pith a (1), recycled jute fibre c (1), thistle fibre c (1), olive stone e (1) [16,28,35,36,40,45,[57][58][59][60][61][62][63][64][65][66] 3 Animal waste: ground waste seashells b (1) [67] 4…”

“…According to the authors, even adding only 5% spent coffee grounds leads to an important reduction in thermal conductivity and consequently to a greater insulating performance. In the study by Yildiz et al [58], coffee wastes after microwave and ultrasound pretreatment were added to replace cement binder. Based on results for 10%, 20%, and 30% of waste, the authors concluded that ultrasound pre-treated coffee waste improves the thermal properties by reducing the λ-value of the insulation plaster.…”

“…According to the research results, regardless of the binder type, all new mortars showed excellent resistance against salt crystallization, which is favourable for their application in the repair and renovation of salt-laden structures [84]. Yildiz et al [58] carried out fire resistance tests on mortars with coffee wastes. The best fire resistance time was 95 min, with an incorporation percentage of microwave-pre-treated coffee waste of 20% and 30%.…”