Effects of by-product materials (POFA and PFA) as partial cement replacement on concretetowards corrosion reisitance

• Main Author: Fadzil, Mat Yahaya
• Format: Thesis
• Language: English
• Published: 2015
• Subjects: Q Science (General); TA Engineering (General). Civil engineering (General)
• Online Access: http://umpir.ump.edu.my/id/eprint/12959/19/Effects%20of%20by-product%20materials%20%28POFA%20and%20PFA%29%20as%20partial%20cement%20replacement%20on%20concretetowards%20corrosion%20reisitance.pdf; http://umpir.ump.edu.my/id/eprint/12959/

The utilization of pulverized fuel ash (PFA) and palm oil fuel ash (POFA) in producing a new construction material is seen as one of the ways to reduce the quantity of these wastes or by-products disposed at landfills. These materials are identified as pozzolana which are used as a partial replacement of the Portland cement. This step enables building materials to be managed in a sustainable manner, thereby reducing pollutions and landfill areas in the future. PFA is a by-product material produced from the burning of coal in electric power plants, while, POFA is the residue obtained by burning husks or fibers, and palm kernel shells used as biomass in palm oil mills. This thesis presents an experimental study of the engineering properties and durability of concrete based cement blended using different byproduct materials namely POFA and PFA in tackling the reinforcement corrosion problem in concrete. Seven types of mixes were prepared, which consisted of a control mix and other mixes consisting of 10, 20 and 30 percent of POFA and PFA as a partial cement replacement for each by-product. The influence of POFA and PFA replacement level and mixing constituents on the compressive strength of concrete have been investigated under different curing regimes namely water, control room, wet-dry cycle and outdoor up to one year concrete age. Studies on the durability aspect of the mix towards its porosity, microstructure, crystallization product and corrosion resistance are also investigated. The result shows the performance of concrete with 20 percent of POFA and PFA produces a comparable compressive strength with the control mix with water curing regime. The constant presence of moisture is significant for strength development of POFA and PFA concrete mixes since the pozzolanic reaction is only able to take place in the later age, after calcium hydroxide is available from the hydration process in the presence of moisture. Other than that, the utilization of POFA and PFA in concrete improves concrete porosity by improving the microstructure due to the densification of concrete by reducing voids inside the concrete. At the same time, POFA and PFA concrete mixes demonstrate a higher resistance to chloride ion penetrations than the control mix. Due to these reasons, the POFA and PFA concrete mixes have exhibited a good resistance towards corrosion after undergoing accelerated corrosion tests. In this test, the control concrete cracked and failed after two days as compared to POFA and PFA concrete, which took a longer period that are 14 and 21 days to crack due to the corrosion of steel reinforcements. Finally, the study shows that the utilization of PFA as a cement replacement material produces a better performance than POFA in all aspects of concrete properties due to its chemical compound and fineness. As a conclusion, the use of PFA and POFA at the level of 20 percent as the replacement of Portland cement is optimum in concrete and does not affect the compressive strength but also improves the durability of concrete, especially against corrosion resistance. The use and recycling of these materials not only reduces environmental problems and concrete production cost, it can also produce concrete with better properties and performance.