Using Coal Ash for Concrete Block Production
The research team at the Indonesian Institute of Sciences (LIPI) is developing various innovations that could process the coal ash as a raw material for the production of hollow concrete blocks.
Hollow concrete blocks from coal ash waste.
LIPI researchers have been able to process ash from coal combustion into hollow concrete blocks for use in construction. This innovation is expected to allow coal ash to be repurposed.
Coal ash that is not properly managed can bring a negative impact on the environment. The research team at the Indonesian Institute of Sciences (LIPI) is developing various innovations that could process the coal ash as a raw material for the production of hollow concrete blocks.
Based on data from the Electricity Directorate General at the Energy and Mineral Resources Ministry (ESDM), the total production of coal ash – both fly ash and bottom ash (FABA) – in 2019 totaled only 9.7 million tons, which accounted for only 10 percent of the total coal use of 97 million tons during the year.
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Efforts to increase the use of FABA need special attention from related parties because coal ash that is not managed optimally will result in higher piles, which can pollute the environment.
The volume of FABA production in Indonesia is expected to continue to increase in line with the increased use of coal in steam power plants (PLTUs). In 2021, the demand for coal is estimated to reach 162 million tons, which has the potential to result in the production of about 16.2 million tons of FABA, on the assumption that 10 percent of the coal burned becomes FABA.
Therefore, the management of FABA must be improved. The government has removed FABA from the category of toxic and hazardous waste (B3) through Government Regulation No. 22/2021 on the implementation of environmental protection and management, although it has been criticized by a number of parties.
Utilization of coal ash concrete
The government has argued that because the FABA materials are produced from high-temperature coal burning at PLTUs, the unburnt carbon content in FABA is minimal and is more stable when stored. On the other hand, FABA produced by industries that use industrial furnaces or stoker boilers are still included in the category of B3 waste. Both types of waste must be managed and meet standards.
The head of the LIPI\'s Metallurgical and Material Research Center, Nurul Taufiqurochman, said in Jakarta on Saturday (20/3/2021) that so far, innovative products resulting from FABA processing could not be used maximally by people because they were still considered B3 waste.
As the result, the use of FABA is quite minimal. One of the innovative products made from FABA are the hollow concrete blocks developed by the LIPI. FABA as a raw material for the production of hollow concrete blocks developed by the LIPI has met the appropriate strength standards and is more environmentally friendly than conventional concrete.
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Nurul said hollow concrete blocks were processed from a mixture of solid ash, cement, water, additives and a little fly ash. Of the total mixture, the solid ash, or bottom ash, accounts for between 60 and 80 percent.
Excellence
Concrete that is processed from FABA also has various advantages. It has an absorption capacity of up to 30 percent higher than concrete in general, among other perks.
With its hollow structure, the concrete allows water to be absorbed into the ground. This can simultaneously support the addition of water reserves in the ground.
Heavy trucks carry coal in the Tutupan Block, which is mined by PT Adaro Indonesia on the border of Tabalong and Balangan Regencies, South Kalimantan, Wednesday (19/5/2010).
The concrete is also suitable for use in flood-prone areas because it has an absorption capacity of around 1,000 millimeters per day. Conventional concrete generally absorbs less than 10 millimeters per day.
"The hollow concrete blocks developed by LIPI also have a strength of 250 to 350 kilograms per centimeter. With this strength, this concrete can be used for roads in houses, sidewalks or parking lots, "said Nurul.
He said that the use of coal ash as a raw material for concrete did not bring a negative impact on the environment or society. A number of studies have also found that the heavy metal content of coal ash waste, such as fly ash and solid ash, are within the allowable limit
This concrete can be used for roads in houses, sidewalks or parking lots.
The Environment and Forestry Ministry also stated that the results of the study and characteristic tests by experts showed that the FABA produced by the PLTUS was still within the quality standard limit for dangerous and toxic characteristics.
Patent
At the beginning of the development of the hollow concrete locks, LIPI collaborated with the Japan International Cooperation Agency (JICA) and Hakko Industry Co., Ltd. Through this cooperative effort, LIPI received a number of presses to make the concrete blocks. The tool can be replicated and produced domestically.
With this tool, the expected strength of the concrete can be achieved. In addition, the technology embedded in this tool is also capable of producing concrete that can absorb heat so that it is more comfortable for walkers. The LIPI’s technology to produce hollow concrete blocks from FABA received a patent on August 7, 2020.
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Heavy equipment operates to transport coal at Muarajati Pier, Cirebon Port, West Java, Monday (9/11/2019).
According to Nurul, the utilization of FABA has great potential in Indonesia as most of the country’s electricity is still generated from coal-fired PLTUs. Therefore, various interventions and supports need to be done so that it can be optimally produced.
The support is especially needed from the PLTUs. The FABA treatment plant should be built near the industry so that the transportation of the coal ash is easier. In addition, training is also needed for the surrounding community so that they can independently manage FABA to make it a more useful product.
This is prospective because it can replace the split stones that have been obtained by dredging mountainous rocks.
The government also needs to make special regulations to standardize FABA processing. The coal ash cannot only be used as a raw material for concrete production. LIPI is currently also developing FABA into split stones.
"This is prospective because it can replace the split stones that have been obtained by dredging mountainous rocks," said Nurul.
Director general of electricity at the Energy and Mineral Resources Ministry, Rida Mulyana, said that well-managed FABA could provide benefits for the country, especially in infrastructure development (Kompas 16/3/2021). The Indonesian Chamber of Commerce and Industry (Kadin) has estimated that the use of FABA as a mixture of concrete raw materials could potentially save up to Rp 4.3 trillion (US$298 million) in infrastructure spending by 2028.
This article was translated by Hendarsyah Tarmizi.
