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Abstract

Continuous monitoring of strength gain in fresh cementitious system is an important assessment for determining the long term strength gain properties in concrete. The present study is aimed to evaluate the setting characteristics of fresh cementitious systems containing ordinary Portland cement (OPC) and flyash blended cement. Also, the influence of accelerators on the rate of strength gain in flyash concrete was studied systematically. A fabricated plexiglass mould was used to monitor the setting properties of fresh cement paste using an ultrasonic pulse velocity at different time intervals for different cementitious systems. The test results indicated that the pozzolanic reaction of flyash in cement was enhanced with the addition of accelerator. Also, a drastic reduction in setting time was noticed for large replacement of flyash (40%) at increased dosage of accelerator (upto 3%). However, the rate of hardening was found to be consistently higher for an optimum flyash replacement (30%) in cement with1% of accelerator dosage and exhibited a highest compressive strength of 42.21 MPa. It can also be concluded from the ultrasonic pulse velocity test results that the cementitious system containing 20% flyash in cement with the addition of 3% accelerator dosage recorded a good improvement in the early age strength.