**2.2 Sample preparation and testing**

POC was used as replacement of sand in mixture of 1:4 (one parts of cement to four parts of river sand by weight). The replacements were 25%, 50%, 75% and 100% in four mixtures using volume method. **Table 1** summarises the five mixes used including the reference sample (without replacement). During mixing, cement and fine sand aggregate were first mixed for about two minutes, followed by
