Abstract
This study investigates the engineering performance and CO2 footprint of mortar mixers by replacing Portland cement with 10%, 20%, 40% and 60% fly ash, a common industrial waste material. Samples of self-compacting mortar (SCM) were prepared with four different water/binder ratios and varying dosages of superplasticizer to give three ranges of workability, i.e., normal, high and self-compacting mortar mix. The engineering performance was assessed in term of compressive strength after designated curing periods for all mixes. CO2 footprint was the environmental impact indicator of each production stage. The optimum mix obtained was at 10% replacement rate for all mixes. Total production emission reduced by 56% when the fly ash replacement rate increased from 0% to 60% (maximum). This is translated to a reduction of 80% in eco-points (assuming that the energy consumption rate of production with 0% fly ash is at 100%). Such re-utilization is encouraged since it is able to reduce possible soil toxicity due to sulfur leaching by 5% to 27% and landfill area by 15% to 91% on average.
Highlights
Self-compacting mortar (SCM) is an integral part of a self-compacting concrete (SCC) design, a technological evolution of the conventional concrete that does not require any vibrator for compaction.The self-compacting ability of fresh concrete enables it to fill formwork and encapsulate reinforcing bars through the action of gravity while maintaining homogeneity [1]
The equations clearly showed that an increase in the line gradient has produced a much higher optimum mix for self-compacting mortar determined based on the relationship rangeThe of compressive strength for all mixes
The results suggest that, rather than w/b ratio, the type of fly ash plays a more dominant role in affecting the strength and CO2 footprint of the SCM mixes
Summary
Self-compacting mortar (SCM) is an integral part of a self-compacting concrete (SCC) design, a technological evolution of the conventional concrete that does not require any vibrator for compaction. The ability to self-compact has made SCC an attractive choice internationally, but its higher manufacturing cost than conventional concrete has hindered its application in general construction. SCM is preferred due to its ease of mixing while having excellent flowing ability [6] This reduces casting costs and, again, produces a more homogeneous product. Putri et al [21] studied the effect of fly-ash on the environmental sustainability and engineering performance of OPC-mortar. The utilization of waste material in cement mortar promotes green technology Waste materials, such as fly ash, that are deposited into landfills without further consumption consume more space than necessary, not mentioning that they bring adverse environmental impacts, such as leaching and groundwater contamination. Several authors [25,26,27,28,29] have attempted to relate environmental sustainability from other aspects by utilizing waste materials as supplementary cementing materials where the zero burden hypotheses (co-combustion of fly ashes) were implemented
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