Assessment of the Mechanical and Time - Dependent Properties of Ambient Cured Metakaolin – Based Geopolymer Concrete

Abstract

Development of geopolymer concrete using locally sourced kaolin can lead to a significant reduction of the carbon footprint of
concrete and also increase the economic value of kaolin which is deposited in large quantity in most part of Nigeria. There is limited
information available on the structural characteristics of geopolymer concrete that is based on other material than fly ash and blast
furnace slag. Hence, assessment of mechanical and time – dependent properties of metakaolin based geopolymer concrete is
important to ascertain the suitability of locally sourced material for the development of structurally viable geopolymer concrete. It
has been established that the ambient cured metakaolin based geopolymer concrete (MGC) exhibited a higher strength than the
conventional Portland cement concrete. The mechanical strength properties tests revealed that MGC recorded a rapid strength
development by achieving approximately 90% - 95% of 28days strength within 3days of ambient curing, whereas, PCC could
achieved approximately 43% of its 28days strength within 3days of water curing. At 28days the MGC recorded approximately
18%, 13% and 9% higher compressive, flexural and tensile strength respectively than PCC of equivalent mix content. The time –
dependent tests revealed that the geopolymer concrete had a marginal 5% lower elastic modulus than PCC. At about 180 days, a
lower shrinkage of about 66% and a reduced total creep coefficient of about 38% was recorded for MGC in comparison with PCC.
It can be concluded that the metakaolin geopolymer concrete offers notable advantages in structural performance than the
conventional Portland cement concrete.