Jul 1, 2016: Resource conservation, energy efficiency, consuming waste for productive use are ways to make Earth greener. In a way, being sustainable is, getting more by using less. Sustainable concrete requires minimizing the resource usage for specified performance. That is why in this special issue on Sustainability, I would like to start with a Point of View!
It is a common practice in India to prescribe certified mix proportions for producing concrete. Such conservative practice is detrimental to development of concrete technology in the country. Statistical quality control (SQC) used for concrete production is highlighted in this paper. While in case of infrastructure projects modern construction practices are often adopted, in bulk of other constructions such practices are seldom applied. Adoption of total SQC and mix design and control at plant is one way of sustainability by minimizing wastage of resource.
Demolished concrete from buildings has become a waste disposal concern. With recycling techniques, it can be used as an alternative source for normal coarse aggregate to help resolve waste disposal issues and overcome short supply of normal coarse aggregate for concrete. This research investigates the performance of self-curing concrete with recycled coarse aggregates. Second paper on recycled concrete aggregate (RCA) presents a comparative evaluation of RCA obtained from a commercial recycling plant with respect to a natural virgin aggregate.
Ferrochrome ash (FCA) is a waste material obtained from ferrochromium industry. Flexural behaviour of RC beams containing 40% FCA and 7% lime replacing 47% OPC indicate better performance of FCA concrete than control concrete in terms of load carrying capacity, crack resistance ability and ductility.
Pond-ash, a mixture of bottom ash and fly ash generated in coal based thermal power plant after their disposal in the pond through wet slurry transport process has been reported as a good replacement for natural sand. Development and performance properties of ‘ashcrete’, a high strength cement based matrix made with pond-ash are investigated in this paper.
Disposed glass used in residential buildings for sliding windows, table tops, shelves, etc is ground and this waste glass powder (WGP) is used as partial replacement of ordinary Portland cement (OPC) in cement paste, mortar and concrete. Study indicates gain in strength for mortar from 28 to 56 days being higher, and for concretes is marginally lower than that of OPC and fly ash based mortar and concrete respectively. Resistance to chloride ion penetration of the concrete improves with increasing replacement of OPC with WGP.
An analysis is conducted with the objective to determine the dependency of quantity of materials used in SCC on the variation in characteristics of unconventional materials. It comes out that specific gravity and loose bulk density of aggregates have significant influence on the total quantity of the material and play an important role especially when unconventional materials are used in the production of SCC.
The potential of rice husk ash (RHA) as an alternate cementitious material is evaluated. The XRD test results and chemical analysis of RHA confirm that RHA has the potential to be used as alternate cementitious material and could be blended with cement without adversely affecting the strength properties of concrete. Improving efficiency and reducing costs is also contributing to sustainable practices. In a slightly varied topic, the point of view is by way of a case study focusing on bulk transportation to improve efficiency and effectiveness for both inbound and outbound logistics through Value Engineering techniques.
On the topic of inconsistent results in waste utilization in concrete a point is highlighted as to how everyone’s claims on improvement in properties of concrete are not uniform. Some suggestions emerge to have consistent results going forward. Materials, methods, practices, efficiency as you see are all contributing to sustenance and sustainability.
We do hope you find these enriching and value adding. Do write to us with your views and topics of interest.
With Best Regards,
Ashish Patil