IO, Solo – Coal is still the most efficient and cheapest primary energy source used by national power plants to create electricity. Unfortunately, the fly ash (FA) created by burning it contains heavy metals which are harmful to the environment and human health. However, fly ash can now be used to create lightweight foamed concrete (LFC) wall panels which can cut construction costs and the energy consumption of buildings.
During the open dissertation defense for his doctoral program in the UNS Postgraduate Building on Wednesday (30/1/2019), building engineering lecturer from the UNS Faculty of Teacher Training and Education Ir. Chundakus Habsya MS. Ars., explained that when coal is used as an energy source in power plants two types of waste are created: bottom ash and fly ash. There is 80% more fly ash created during the process than bottom ash. The fly ash is also more dangerous as it contaminates the air with heavy metals. If inhaled it can cause health issues including increasing the risk of cancer.
As a result, as a building engineering expert in the environmental field, Chundakus went out to research and design a use for the fly ash as material for wall panels. Most walls use bricks even though they are heavy causing their structural load and thermal conductivity to be high. Consequently, the walls pass on heat from the outside quickly.
Chundakus offered a solution in the form of wall panels created from lightweight foamed concrete (LFC) mixed with fly ash (FA) as it has low density, high compressive strength, and low conductivity, meaning it could decrease the load, density, and cost of the structure, alongside reduce energy costs for cooling. “LFC is a good heat insulator, suitable for Indonesia which has a tropical climate and tends to need cool buildings,” said Chundakus, during his dissertation defense titled “Usage of Coal Fly Ash Waste for Lightweight Foamed Concrete Wall Panels Reviewed from Physical and Mechanical Characteristics.”
The research was done by testing a mixture of cement and sand to the ratio of 1:2, 30%-50% of mortar volume in foam, and 0%-60% of sand volume in fly ash. “The LFC-FA wall panel’s compressive strength passes ASTM (American Standard Testing and Material) for partitioning concrete meaning it is safe to be used. The weight of 1 m3 of LFC-FA is 28.35% lighter than brick walls. The thermal conductivity of LFC-FA wall panels is 23.3% lower than brick walls.”
According to monthly energy consumption simulations for type-30 (T-30) buildings using the program DesignBuilder, LFC-FA wall panels are 8% more efficient than brick walls. Budget cost calculations based on standards and calculations from the Central Java Human Settlements and Spatial Planning Agency resulted in 4% savings compared to when brick walls are used. LFC-FA wall panels also had a far lower pollutant content than the amount regulated in Presidential Regulation No. 101/2014.
The use of LFC-FA wall panels is more beneficial as 1.57 tons of LFC-FA produced every month would decrease 800 tons of fly ash per month (5% of the fly ash waste created by the Tanjung Jati Jepara power plant). The construction of T-30 buildings using LFC-FA wall panels would also be 4% cheaper and would consume 8% less energy during construction compared to if using brick walls.
The Pekalongan-born doctoral degree holder added that the use of LFC-FA wall panels would not only benefit homeowners but also developers as construction using the material would be easier and faster compared than using bricks while also saving 4% in building costs. The reduction in weight for high-rise buildings would also be significant as every 1 m3 of LFC-FA wall panel is 28.35% lighter than that made of brick. (UNS Public Relations)