Preparation of Natural Materials with Organic Phase-Change Materials before Mixing in Concrete Blocks for Reduce Heat Conduction to the Building

Abstract

Concrete blocks are widely used in building construction due to the low cost that the selection of materials in the current construction focuses on energy consumption. Concrete blocks are a mixture of cement, stone, gravel, which conducts heat into the building and makes it heavy. Therefore, fibers from various natural materials with cellulose fibers are used as an ingredient to replace the original material. However, there was a problem of cellulose fiber with moisture absorption properties, resulting in higher thermal conductivity in concrete blocks. This research aims to study factors affecting moisture and develop a method to reduce moisture in concrete blocks by using natural phase change material (PCM) to be applied in the natural material preparation process before being mixed in concrete blocks.

The results showed that the methods of moisture passing through the building frame system causes moisture to accumulate in the material, namely the Capillary Suction Method and the Vapor Diffusion Method, resulting in an increase in the thermal conductivity coefficient of the material. In such a way, it was found that indoor temperature is higher, consequently a lot of energy is required for air conditioning to stay comfortable. The method of dehumidification in concrete blocks that does not affect the physical properties of the material is to use latent heat energy in the concrete block mixture. It uses the phase change material (PCM) principle to prevent moisture from entering the concrete block.

The study of properties of natural materials suitable for use as mixture in concrete block found that monocots are physically appropriate because they can bind to other aggregates to reduce moisture content. Thus, the material preparation cost is low. Therefore, rice husk and coffee husk were compared through the water absorption test process with the application of phase change materials (PCM).

Based on the study of the types of natural phase change materials suitable for application in this research, it was found that the formula with the ratio of the palm phase change material and the soybean phase change material at the rate of 1:1 can reduce the melting point temperature to 37 °C - 67.5 °C. And the Encapsulation phase change material technique was applied to natural materials by coating mixing method on the surface of the material before being put to the water absorption test for 24 hours to compare the lowest water absorption rate and the most sensitive dehydration of the rice husk and the coffee husk, it was found that formulations with a mixture ratio of 1 kg of coffee husks per 20% mixed phase change material to 70% of latex had the lowest water absorption rate and took the most time before reaching saturation point. And after 2 hours, the rate of dehydration was the fastest. It is considered that this test formula has good results. It is suitable to be used as a prototype formula for pretreatment of natural materials before being mixed in concrete blocks to reduce moisture content that will occur in concrete blocks.