Investigation of flexural strength of concretes containing rice husk and saw dust ashes from different calcination methods
Date
2016-07
Authors
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Publisher
Federal University of Technology, Owerri
Abstract
This work investigated the flexural strengths of concretes containing rice husk ash (RHA) and saw dust ash (SDA) from different calcination methods. RHA and SDA were produced using three different calcination methods namely, Open-Air (OA), Furnace (F), and Stove (S). Each of RHA and SDA was used as partial replacement of Ordinary Portland Cement (OPC) at 5%, 10% and 15%. 171 concrete beams of dimensions 150 x 150 x 600mm were produced using 1:2:4 cement–sand–sandstone mix ratio and 0.6 water/cement ratio. This comprised 81 OPC– RHA, 81 OPC–SDA and 9 OPC (control) concrete beams. The beams were cured by immersion and tested for flexural strengths at 28, 90 and 150 days. The results showed that the flexural strength of the blended cement concrete increased with curing age and decreased with increased amount of RHA and SDA. The 150th day flexural strengths for 5% RHA were 5.35 Nmm-2 for OA, 6.74 Nmm-2 for F and 5.20 Nmm-2 for S. Corresponding strengths at 5% SDA were 4.48 Nmm-2 for OA, 5.85 Nmm-2 for F, and 4.28 Nmm-2 for S, while the Control value was 6.41 Nmm-2 . Thus, for 5% replacement of OPC with RHA, OA calcination had 83.5% the strength of the control; F calcination had 105.1% the strength of the control, while S calcination had 81.1% the strength of the control. Similarly, for 5% replacement of OPC with SDA, OA calcination had 69.7% the strength of the control; F calcination had 91.3% the strength of the control, while S calcination had 66.7% the strength of the control. Therefore, although furnace calcination gave higher strength than open-air and stove calcinations, the latter two could still be used for structural members with lower flexural strength.
Description
This thesis is for the award of Master of Engineering (M. ENG.) Degree in Civil Engineering
Keywords
Concrete, blended cement, pozzolan, rice husk ash, sawdust ash, flexural strength, sandstone aggregate, mineral admixture, workability, calcination, Department of Civil Engineering
Citation
Amadi, S. O. (2016). Investigation of flexural strength of concretes containing rice husk and saw dust ashes from different calcination methods [Unpublished Master's Thesis]. Federal University of Technology, Owerri, Nigeria