The strength of fly ash bricks can be significantly enhanced by optimizing the mix proportions and following specific manufacturing techniques.
Mix Proportions
The primary components of fly ash bricks are fly ash, sand or stone dust, sludge lime, and often cement. The optimal proportions suggested for these ingredients are as follows1:
- Fly Ash: 55 to 65%
- Sand or Stone dust: 20 to 25%
- Sludge Lime: 15 to 22%
Another study suggests a mixture ratio of fly ash (41%), cement (25%), lime (15%), shell ash (15%), gypsum (4%), and Styrene Butadiene Rubber (SBR) (3%) can result in strong unburned bricks2.
Manufacturing Techniques
Certain manufacturing techniques can also enhance the strength of fly ash bricks. For instance, adding 5% Portland cement or lime, using higher compaction pressure during moulding, and lengthening the curing process can all result in stronger bricks.
Fly ash bricks are known for their uniform shape, which requires less mortar in construction. They can be made in various sizes and shapes to suit different projects4. These bricks have a compressive strength of up to 200 kg/cm², making them an ideal choice for building structures that need to withstand heavy loads.
The main ingredients include fly ash, water, quicklime or lime sludge, cement, aluminum powder, and gypsum6. These components, when combined in the right proportions and manufactured using the appropriate techniques, result in bricks that are lighter and stronger than traditional clay bricks.
Remember, the quality of raw materials and the manufacturing process plays a crucial role in determining the strength and durability of fly ash bricks.
Footnotes
- how to make fly ash bricks strong