Setting time and microstructure of Portland cement-bottom ash–sugarcane bagasse ash pastes

Monatshefte für Chemie - Chemical Monthly, May 2017

Aniruj Akkarapongtrakul, Phongthorn Julphunthong, Thanongsak Nochaiya

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Setting time and microstructure of Portland cement-bottom ash–sugarcane bagasse ash pastes

Monatsh Chem Setting time and microstructure of Portland cement-bottom ash-sugarcane bagasse ash pastes Aniruj Akkarapongtrakul 0 1 2 3 Phongthorn Julphunthong 0 1 2 3 Thanongsak Nochaiya 0 1 2 3 0 Department of Civil Engineering, Faculty of Engineering, Naresuan University , Phitsanulok 65000 , Thailand 1 Department of Physics, Faculty of Science, Naresuan University , Phitsanulok 65000 , Thailand 2 & Thanongsak Nochaiya 3 Research Center for Academic Excellence in Applied Physics, Naresuan University , Phitsanulok 65000 , Thailand Bottom ash (BA) and sugarcane bagasse ash (SCBA) are by-products from power plants and the sugar industry and they have a great potential to be used in greenconcrete structure applications. This study reports the effects of BA and SCBA on the properties of Portland cement (PC) pastes and mortars as cement replacement, by up to 20 percent by weight. All mortars had a water to binder ratio (w/PC ? BA, w/PC ? SCBA, and w/PC ? BA ? SCBA) of 0.5. Normal consistency, setting time, compressive strength, and microstructure (using scanning electron microscope, SEM) were systematically investigated. The results showed that the water requirement for a normal consistency was decreased with increasing BA content. The addition of SCBA, on the other hand, caused the water requirement to increase. The initial and final setting times of all pozzolan mixes were longer when compared to that of PC mix. The compressive strengths of all mixtures with BA were similar to that of the PC mix at 90 days. In addition, the SEM micrograph of pastes confirmed a good pozzolanic reaction between ash particles and Portland cement, resulting in an increase in the compressive strength of the mortars, especially after a period of time (more than 28 days). Graphical abstract; Bottom ash; Sugarcane bagasse ash; Pozzolanic reaction; Hydration reaction Introduction Cement is the principal material used in the production of concrete, which is the most important material in the world. Concrete forms the basis of the construction industry today, but it emits CO2 at a rate of 0.7–1.1 tons for every ton of cement produced [ 1 ]. To reduce the amount of CO2 emissions from the cement industry, the manufacturing process has to be improved to reduce its emissions of air pollution [ 2 ]. Methods of reducing air pollution include utilizating supplementary cementitious materials such as natural pozzolans material [ 3–5 ]. Bottom ash (BA) is a by-product of the combustion of coal in power plants and is formed when ashes at the bottom of the furnace are consolidated. Bottom ash particles are physically coarse, porous, granular, and graying color. The world production of coal ash was approximately 459 million tons in 1992 [ 1 ] while the output of lignite BA at Mae Moh power plant in the north of Thailand is about 0.8 million tons per year [ 6 ]. Many researchers have reported that BA contains a high silica and alumina contents similar to fly ash. Furthermore, it has been reported that the pozzolanic reactivity BA may improve the compressive strength of concrete [ 7–9 ]. Several researchers [ 10, 11 ] found that grinding BA can increase its pozzolanic activity in the concrete and make it suitable for use as a partial replacement in Portland cement. Sugarcane bagasse ash (SCBA), which is a by-product of the burning of sugarcane bagasse from the sugar industry, has recently been accepted as a pozzolanic material and can be used as a supplementary material in cement-based materials [ 12–16 ]. However, the SCBA is a pozzolanic material with high silica content, which could also be used as a pozzolan [ 15 ]. This ash is generally disposed in landfills every day, leading to environmental problems in the region. Since the SCBA received from the sugar industry has a large particle size and high porosity, Fig. 1 Normal consistency of PC containing BA and SCBA paste the concrete made with it needs higher water content that gives the concrete lower mechanical properties. However, when SCBA is ground into small particles, the properties of the cement-based materials containing ground SCBA improves significantly [ 17 ]. Ganesan et al. [ 15 ] reported that the SCBA was an effective mineral admixture, with 20% by weight of the binder as optimal replacement ratio of cement. The 28- and 90-day compressive strengths have been higher than that of the mix without SCBA. The relationship between the microstructure and compressive strength of BA and SCBA blended cement is not well reported. Consequently, this research investigated the effect of ground BA and SCBA on the microstructure, setting time and compressive strength of pastes and mortars and compared them to the PC control mix. This knowledge could be beneficial and used commercial to incorporate these wastes products into concrete, leading to a reduction in the amount of cement used and environmental problems associated with cement production. Results and discussion (...truncated)


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Aniruj Akkarapongtrakul, Phongthorn Julphunthong, Thanongsak Nochaiya. Setting time and microstructure of Portland cement-bottom ash–sugarcane bagasse ash pastes, Monatshefte für Chemie - Chemical Monthly, 2017, pp. 1355-1362, Volume 148, Issue 7, DOI: 10.1007/s00706-017-1953-5