Impact of Cement Replacement by Sawdust Ash on Workability and Compressive Strength of Concrete

Abstract

In this research paper, we analyze the effect of saw dust ash as cement replacement on compressive strength. Sawdust collected from wood workshops of Nawabshah city was converted into ash by burning and grinding. Six concrete mixes with ash dosage of 2.5% to 15% in the increment of 2.5% were developed. Also, a mix with conventional ingredients was developed as control mix. Workability by slump test shows a higher demand of water in the mix with sawdust ash, otherwise mechanical effort or admixtures will be needed to maintain the workability. Total 63 standard size cylinders were cast using 1:2:4 mix and 0.5 water cement ratio. In each mix, 9 cylinders were cast, out of which equal number of cylinders were cured for 7, 28 and 56 days. Weight of the specimen shows that sawdust ash is
helpful in developing light weight concrete. Increased dosage of the waste ash produces lighter concrete. Comparison of compressive strength of the saw dust concrete mix with conventional concrete shows that 5% replacement of cement with the waste ash is the optimum dosage. At this dosage, the decrease in compressive strength is 11.66% and reduction in weight is about 2%. Although, the elongated curing shows improvement in strength results, but at optimum dosage the reduction in compressive strength up to 12% was recorded as compared to 28-day cured specimens.