Compressive and flexural strength of cement mortar blended with cassava peel ash and high-range water-reducing (superplasticizing) admixtures

This paper presents the outcome of an experiment carried out by using cassava peel ash (CPA) of varying quantities to partially replace cement in mortar mix and the influence of adding superplasticizer in the mortar mix is further investigated. The experiment was carried out by partially replacing CPA in the range of 0 to 25 percent by weight of cement at 5% intervals. A water binder ratio (w/b) of 0.5 and superplasticizer dosage of 1.5l/100kg were used to produce the blended mortar of mix 1:3. The samples were cured and tested for compression and flexure at 7, 28, and 90 days after demolding. The results of the first experiment confirmed the suitability of the cassava peel ash (CPA) at not more than 15% replacement with cement for mortar and concrete works. In the second experiment, the superplasticizer has a linear relationship with the conventional mortar while the blended cement-cassava peel ash (CCPA) mortar retarded in strength at an early stage. However, 5% CPA mortar with superplasticizer gained 52 percent strength from 7 days to 28 days of the test. In addition, at the 90-day test, 5% CPA mortar with superplasticizer has almost an equivalent strength (96%) of the conventional mortar with superplasticizer. The flexural strength for blended CCPA mortar of 5-15% showed an acceptable value with that of mortar with a superplasticizer. Generally, the addition of admixture to the blended CCPA mortar showed a different trend compared to the conventional mortar.