• Fly-ash bricks are made from a mixture of coal ash, fine sand, cement, and water, hence it is also called ‘cement-brick’.
• These bricks are hi-tech, superior-quality bricks that are used for building structures like brick walls, etc.
• To make this brick, 55% fly ash, 35% stone dust + sand, and 10% cement are taken.

• Demerits: Clay brick masonry wall material is relatively large, so the structure has to withstand more load, which increases the construction cost.
• Large-scale environmental damage, mainly soil excavation, damages soil and vegetation, resulting in soil erosion.

The disadvantage of clay bricks:-

dated February 25, 2019, mandates that ‘No new red clay brick kiln shall be installed and operated within 300 km from a coal or lignite based thermal power plant and the existing red clay brick kilns located within 300 km shall be converted into fly ash based bricks or blocks or tiles manufacturing within one year from the date of publication of this notification.

Features and usefulness of bricks –

• These bricks are of the right size, with equal corners, so the finishing comes on both sides of the wall, due to which cement is also saved in plaster.
• This brick absorbs less water, so there is no seepage in the wall of the house, the paint does not deteriorate and the wall putty does not shed.
• This brick is heat-resistant, so the house made of it takes less heat.
• That fly ash brick is nothing but a slow-setting pozzolana cement mix. The process is similar to making cement in cement factories while clay…
• Compressive Strength: 100kg/cm2
• Properties: Red Bricks / Clay Bricks
• Density: 1600-1750kg/m3
• Wastage during transit: up to 10%

• Fly ash:-
• Fly ash is a fine powder obtained as a by-product from the burning of coal in thermal power plants.
• It contains heavy metals as well as PM 2.5 and black carbon. The PM 2.5 found in it spreads through the air for 20 kilometers in summer.
• Density:- 1.9-2.9g /cm3.
• The traders can sell fine fly ash in retail in the domestic market at the rate of Rs 1,200 to 1,400 per tonne

 Fly ash disadvantages

• Fly ash contains substantial amounts of oxides of silica, aluminum, and calcium. Elements such as arsenic, boron, chromium, and lead are also found in small amounts. Thus, it creates a serious threat to the environment and health.

• stone dust:-
• Stone dust is the waste material obtained from the crusher plant. It has the potential to be used as a partial replacement for natural river sand in concrete.
• The use of stone dust in concrete not only improves the quality of concrete but also preserves the natural river sand for generations to come.
• Specific density:- 2464 kg/m3.
• The traders can sell fine fly ash in retail in the domestic market at the rate of 600/ Tonne.

• Sand:-
• here are four common sources of sand: weathering on continental granitic rock, weathering of oceanic volcanic rock, skeletal remains of organisms, and precipitation from water

• Making fly ash brick used 15% sand.
• The traders can sell fine fly ash in retail in the domestic market at the rate of 450/ Tonne.

Per batch material mixing capacity – 500KG

   500 Kg – 142 bricks

1.fly ash bricks are manufactured by hydraulic or vibratory press.

2.raw material required are fly ash, shall conform to grade 1 or grade 2 of IS 3812 (60-65%), bottom ash used as replacement of shall not have more than 12 percent loss on ignition when tested according IS 1727, lime shall conform to class C hydrated lime of IS 712 (8-12%), gypsum(5%), locally available sand/stone dust  (18-27%) and water.

3.ordinary Portland cement can also be used in place of hydrated lime and gypsum.

4.raw materials in the required proportion are mixed in the pan mixer to have asemi dry uniform mix.

5.semi dry mixture is placed in the mould of hydraulic / vibration press.

6.moulded bricks are air dried for one/two days in a shed depending upon the weather conditions and then, submerged in the water for 48 hrs then after water cured for 14-21 days.

7.the bricks thus produced are  sound, compact and uniform in shape.