Geopolymer Concrete as a Sustainable Alternative in Pavement Construction: Comparative Analysis with Conventional Concrete

Abstract

The study examines the potential of utilising rice husk ash (RHA), metakaolin (MK), and
cementitious solutions in the formulation of geopolymer concrete (GPC) as a replacement for
conventional concrete in pavement applications. Conventional concrete made from OPC is not
ecofriendly due to several factors, such as high CO₂ emissions, intensive energy consumption,
depletion of natural resources, etc. This study necessitated the search for an alternative ecofriendly
approach to address these limitations. The interaction between RHA, MK, and the cementitious
solution for possible improvement in concrete pavement applications was investigated. RHA and
MK were locally produced from the calcination of rice husk and kaolin at temperatures ranging
from 600 to 800°C, while cementitious solutions were sourced in Ibadan. The constituent
cementitious solutions—1M NaOH and 2M Na₂SiO₃ were solubilised in 1 litre of distilled water
and 0.12% SP430. The experimental design applied RHA:MK (30:70, 50:50, 70:30) to a
cementitious solution (kg/kg) at a 2:1 ratio, alongside fine and coarse aggregates. Laboratory tests
conducted include compressive strength (CS), slump test (ST), and specific gravity (SG). The data
were analysed using an ANOVA at the 0.05 significance level. The control and modified concrete
were evaluated at 7, 14, and 28 days. The CS for control and modified concrete reached up to 40
MPa at 28 days. The 30:70 RHA:MK mix yielded the highest strength. This research indicates that
GPC derived from RHA and MK has great potential to replace OPC-based concrete in pavement
applications. Practical evaluation of geopolymer technology in greening intrastate road
infrastructure is recommended.