Improving workability, strength and appearance in interlocking blocks using grinded paddy husk ash

Abstract

Road paving plays a vital aspect in urban development prospect. "Uni Natural" Interlocking blocks (Size: 220mm x 110mm x 80mm) are becoming very common in many parts of the country. With the initial field studies; it was found that the mix proportions were roughly, 1: 2: 1½: ½ {Cement: River Sand: Chips: Quarry Dust} and the water Cement ratio is around 0.4. These blocks were mainly produced with mechanical vibration. During the casting process; it was observed that, when removing off the casted blocks with the pallet board, some of the blocks break (approximately 10%) which results in a fairly rough surface. To overcome this problem it is proposed to introduce grinded paddy husk ash (GPHA) as a filler material, which is freely available in most parts of the country. In brief, different percentages of grinded paddy husk ash was added to the mixture and blocks were tested after the curing process. In addition, workability, compressive strength was also tested using the available standard tests. The best mix proportion which was obtained will help to introduce a paving block with high strength and pleasing visual properties. Since the paddy husk ash is freely available in many part of the country and the current disposal method is burning; this project will lead to an environment friendly and cost effective paving block manufacturing process.