Abstract:
Over the years, the unceasing growth and development in the construction industry has resulted in
both positives and negatives. The extensive use and disposal of many of the materials used in
construction have resulted in the depletion of natural resources, together with piling up of large
amounts of construction and demolition waste in landfills, causing adverse effects on the
environment, the economy as well as society. The most extensively consumed material in the
construction industry can be identified as concrete. Procurement and transportation of raw
materials for cement and aggregates which are the two major constituents used in concrete
production add significant disturbances to the ecological system. Thousands of research studies
have shown the feasibility of using recycled aggregates to produce both normal and high strength
concrete with comparable properties to conventional concrete. However, it requires a more allinclusive
approach in producing an environmentally friendly solution. This paper discusses the
procedure followed in producing cost effective and economical high strength concrete through the
composite use of pozzolans namely fly ash, silica fume and rice husk ash (RHA), in both stages
of aggregate treatment and concrete production. Results from aggregate testing showed a 26%and
59% reduction in aggregate water absorption and porosity, respectively. Further, enhancements in
terms of aggregate specific gravity and crushing value were obtained. Concrete which contained
RHA in both stages, attained a compressive strength of 55.4 MPa, which was even higher than the
control mix containing natural aggregates. The same mix of concrete showed a 12% increase in its
surface resistivity. This indicates the possibility of achieving high strengths, even with the use of
RA derived from parent concretes of lower grades, and not many studies have focussed on this
aspect of high strength recycled aggregate concrete production (HS-RAC).
Citation:
Fernando, A.M., & Gamage, J.C.P.H. (2021). Composite effects of pozzolans in producing high strength recycled aggregate concrete [Abstract]. In P. Hettiarachchi (Ed.), Proceedings of Civil Engineering Research Symposium 2021 (p. 5). Department of Civil Engineering, University of Moratuwa.
