Study on strength and durability of cellular cementfly ash blocks

Abstract

Fly ash which is a waste product collected during coal combustion has become an issue to the environment and human due to lack of proper disposal methods. The major barrier of fly ash not being used as a land filling material is its heavy metal composition. The usage of fly ash in concrete may also vary with the composition of unburned carbon in fly ash. If used in optimum proportions fly ash can give many benefits like cold weather resistance, high strength gains, a good admixture, a non-shrink material, great workability, reduced crack problems, reduced heat of hydration and CO2 emissions. Fly ash can be used in many applications as an additive in building materials such as bricks, blocks, concrete, road and embankment covers. Since fly ash is a by-product it possesses a very low embodied energy which in turn reduces the embodied energy of the product made out of fly ash to a considerably low value. Therefore, the introduction of fly ash into cement sand blocks as a raw material is a better sustainable practice. This research attempt focuses on finding a feasible and an effective solution for the coal fly ash problem in fluidized bed boiler and to check the suitability of coal fly ash cement blocks in building construction. An appropriate mix proportion for fly ash cement blocks is found through trial and error process and various different mix proportions can be tested to obtain a productive and sustainable result in future as well. Tests done for the determination of material properties proved that the raw materials used including fly ash are healthy and robust to be handled and incorporated into a day to day used product. Tests proved that the substitution of fly ash has created very less amount of change to the strength and durability. Also the experiments done on the heavy metal leachate confirms this product is eco-friendly and human friendly. Tests done on durability, strength and thermal properties have confirmed that fly ash can be used as an effective substitute for sand in cement sand blocks.