What is it about?
The aim of this study is to evaluate the usability of new cement (NC) made by the burning of quinary by-product to make commercial binders. Chemical analysis of the by-products and NC as well as X-ray diffraction (XRD) analysis of NC, fineness, density, consistency, and setting time of NC paste, and slump in addition to compressive strength (CS) and splitting tensile strength (STS) of NC concrete (NCC) were conducted. The results suggested that chemical composition of by-products is suitable to make NC binder. The NC contains Ca3SiO5, Ca2SiO5, Ca3Al2O6, and Ca3Al2FeO10. The particles passing through the 200 um Sieve were 56% compared with 52% for Portland cement (PC). The density of the of NC was similar to that of PC. The NC needed 48% more water than PC for normal consistency. The initial and final setting-time of NC was 105 min and 225 min respectively which is much higher than that of PC (15 and 45 min). The slump, compressive strength and splitting tensile strength were slightly lower for concrete containing NC compared with that pf PC concrete. Although the CS and STS of NCC are the lowest, the rate of the CS and STS gain of NCC is greater than that of PCC. It was concluded that NC is a viable alternative to PC for the production of greener concrete.
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Why is it important?
The World Bank reported that 2.01 billion tons of the municipal solid waste (MSW) are generated annually in the world, and approximately 230 million tons of it was burned. It is expected that the global municipal solid waste will grow to 3.46 billion tons by 2050 [1]. Considering the fact related to the municipal solid waste, coal bottom ash is another waste material generated by power plants. The annual production of coal bottom ash (CBA) is 25 million tons of coal bottom ash (CBA) in India [2], 14 million tons in US, 4 million tons in Europe [3] and about 1.7 million tons in Malaysia [4] which creates environmental problems for the global society. The majority of CBA is used as landfill material and there is no effort to transform it into construction material or other useful products. This situation is not different for pulverized fuel ash (PFA) where 360 million tons of PFA are generated every year and most of the waste (216 million tons) are still stored on the land. According to the United States Environmental Protection Agency (EPA), the use of PFA for landfilling and for construction materials is not harmful to ground water resources [5].
Perspectives
The new cement is finer than Portland cement with a solid weight of 1200 m2/kg, lighter than Portland cement which reaches 1250 m2/kg. The specific gravity of Portland cement is 3.15 g/ml while the density of new cement is 3.05 g/ml. The initial setting time of Portland cement was carried out 90 min where the Vicat needle penetrated into the cement paste for 24 mm. The initial setting time of the new cement was also tested by the same method by penetrating 25 mm of cement for 105 min after the needle was removed. The final setting time of Portland cement is 180 min while the new cement reaches 225 min.
Dr Gobinath R
SR University, Warangal
Read the Original
This page is a summary of: Development and assessment of cement and concrete made of the burning of quinary by-product, Journal of Materials Research and Technology, November 2021, Elsevier,
DOI: 10.1016/j.jmrt.2021.09.140.
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