FT NEWS

The construction industry adds a great deal to urban pollution. The burnt-clay brick-making process, in particular, involves the use of non-renewable resources (clay from the topsoil), burning of fuel (coal and wood) and emission of harmful pollutants and greenhouse gases (CO2, SO2, nitrogen oxides and suspended particulate matter or SPMs) that directly impact the environment.

We cannot do without brick masonry; so, what is the way out? The answer is using an industrial by-product for making masonry blocks. Fly ash is a by-product of coal combustion in power plants, boilers and refineries. Post treatment in a machine, fly ash can be tailored into bricks that are capable of replacing the regular clay ones. Genius or what?

Fly ash bricks are strong, light and, most importantly, environment-friendly. If you wish to do your part in saving the earth, read on, get inspired and put the ‘healthier’ bricks to use.

Fly ash bricks (FAB) can be made by compressing, curing and toughening fly ash (a fine powdered residue obtained during burning of coal) and water in a machine under constant temperature and pressure. The presence of calcium oxide in fly ash aids in the self-binding of a brick block.

The introduction of ‘FaL-G’ (developed by Indian inventors Dr N. Bhanumathidas and N. Kalidas) made fly ash bricks tougher, more stable and more economical. The FaL-G process involves the mixing of fly ash (Fa), lime (L) and gypsum (G). Cement can replace lime where the latter is in short supply. Early strengthening (due to gypsum) results in elimination of the pressing and curing processes in the making of FABs. This helps reduce cost and time, increasing the energy-efficiency of the process many-fold.

Unlike the clay-brick manufacturing process, the making of fly ash bricks saves energy and resources, lowers delivery time and reduces pollution. Wondering how? Let’s dig deeper.

How is FAB-manufacturing eco-friendly?

The FaL-G process saves considerable quantities of topsoil, a primary material in clay-brick production.

In contrast to the conventional fired brick-making process, which burns huge amounts of coal and emits harmful gases into the air each year, fly-ash bricks are manufactured without the use of coal, thereby reducing energy-use and pollution.

The ever-growing power industry of our country produces fly ash, which is dumped on open lands, degrading the quality of surrounding environment and affecting the health of the local populace. The FAB-manufacturing machines turn this industrial waste into usable building material, leading to substantial saving of open areas, reduced pollution levels and improved health standards.

Why are FABs here to replace burnt-clay bricks?
1. While the strength of a clay brick is dependent on the soil used in its make, the strength of machine-controlled FABs is higher and can be further stabilised with additives. For instance, marble waste, mortar and so on can be added to the FAB sludge to improve the mechanical strength of the brick blocks.

2. The affinity of cement to an FAB is higher than that to a clay brick. This property of FAB construction saves mortar and speeds up the construction process.

3. FABs are lighter than clay bricks; hence, the dead load on the structure and foundation is lowered. Plus, transportation and construction becomes simpler.

4. An FAB is less porous than a clay brick. Due to this, an FAB construction resists fire, heat and water-seepage better than a clay-brick construction. (What a great material to keep our homes cooler and impermeable!)

5. The traditional fired-brick kilns need to shut down during the monsoon period. FABs provide employment all through the year, as they are manufactured in indoor plants.

Gaining prominence
To provide momentum for fly ash utilisation among the industry, the Ministry of Environment and Forests, Govt. of India, has taken an initiative and issued Gazette Notifications to give directions for its proper use and disposal.

The NRDC (National Research Development Corporation) has declared its seriousness in utilising fly ash in making bricks and has offered the knowhow license to many private parties. It has recognised a ‘C-Brick Machine’ that can produce good quality, stable fly ash bricks through a vibro-compaction process.

The CBRI (Central Building Research Institute, Roorkee) has also acknowledged C-Brick technology for producing fly ash bricks that are strong, stable and have a good finish.

The fight is still on
There is a misconception lurking amongst consumers that FABs have low bearing strength. To ensure adequate strength and uniformity in the making of FABs, manufacturers are expected to follow standards specified by the BIS (Bureau of Indian Standards).

Although the goodness of FAB construction is being appreciated and its production is gradually gaining popularity, the brick sector is still partly unorganised. Once FAB gets widely employed and produced in large numbers, the cost will go down substantially.