Search Results (3)

This paper presents the durability indicators for sustainable self-consolidating high-strength concrete (SCHSC) including palm oil fuel ash (POFA) as a supplementary cementing material (SCM). SCHSC mixes were prepared by varying the water to binder (W/B) ratio and POFA content. The W/B ratio was varied in the range of 0.25 to 0.40, and the POFA content differed in the range of 10–30% to produce the desired SCHSC mixes. The tests conducted on the freshly mixed SCHSCs to evaluate their filling ability, passing ability, and segregation resistance were slump flow, J-ring flow, and sieve segregation, respectively. To evaluate the durability of the hardened SCHSCs, the compressive strength, water absorption, and permeable porosity were examined along with the ultrasonic pulse velocity (UPV). The correlations between different hardened properties were derived to ascertain the durability indicators for sustainable SCHSCs. It was observed that most of the SCHSCs possessed excellent filling ability and passing ability with adequate segregation resistance. The test results also revealed that the compressive strength and UPV increased, whereas the water absorption and permeable porosity decreased with a lower W/B ratio and a higher amount of POFA (up to 20% weight content). Moreover, strong correlations were found between the different hardened properties of SCHSC. These correlations were used to determine the durability indicators for sustainable SCHSC with respect to compressive strength, permeable porosity, and water absorption. In accordance with the derived durability indicators, the sustainable SCHSC mixes produced in this study had the durability levels varying from “high” to “outstanding”. Full article

Modeling is a very useful method for the performance prediction of concrete. Most of the models available in literature are related to the compressive strength because it is a major mechanical property used in concrete design. Many attempts were taken to develop suitable mathematical models for the prediction of compressive strength of different concretes, but not for self-consolidating high-strength concrete (SCHSC) containing palm oil fuel ash (POFA). The present study has used artificial neural networks (ANN) to predict the compressive strength of SCHSC incorporating POFA. The ANN model has been developed and validated in this research using the mix proportioning and experimental strength data of 20 different SCHSC mixes. Seventy percent (70%) of the data were used to carry out the training of the ANN model. The remaining 30% of the data were used for testing the model. The training of the ANN model was stopped when the root mean square error (RMSE) and the percentage of good patterns was 0.001 and ≈100%, respectively. The predicted compressive strength values obtained from the trained ANN model were much closer to the experimental values of compressive strength. The coefficient of determination (R²) for the relationship between the predicted and experimental compressive strengths was 0.9486, which shows the higher degree of accuracy of the network pattern. Furthermore, the predicted compressive strength was found very close to the experimental compressive strength during the testing process of the ANN model. The absolute and percentage relative errors in the testing process were significantly low with a mean value of 1.74 MPa and 3.13%, respectively, which indicated that the compressive strength of SCHSC including POFA can be efficiently predicted by the ANN. Full article

Palm oil fuel ash (POFA) has previously been used as a partial cement replacement in concrete. However, limited research has been undertaken to utilize POFA in high volume in concrete. This paper presents a study on the treatment and utilization of POFA in high volume of up to 50% by weight of cement in self-consolidating high strength concrete (SCHSC). POFA was treated via heat treatment to reduce the content of unburned carbon. Ordinary Portland cement was substituted with 0%, 10%, 20%, 30%, and 50% treated POFA in SCHSC. Tests have been conducted on the fresh properties, such as filling ability, passing ability and segregation resistance, as well as compressive strength, drying shrinkage and acid attack resistance to check the effect of high volume treated POFA on SCHSC. The results revealed that compared to the control concrete mix, the fresh properties, compressive strength, drying shrinkage, and resistance against acid attack have been significantly improved. Conclusively, treated POFA can be used in high volume as a cement replacement to produce SCHSC with an improvement in its properties. Full article