Abstract:
Concrete, as the world’s most implemented construction material, is increasingly being used
because of the rapid development of industrialization and urbanization. Limited resources and
progressive depravation of the environment are forcing scientific efforts to seek alternative and
effective materials from large amounts of natural resources as additives in the partial replacement
of cement and Continuous generation of wastes arising from industrial by-products and
agricultural residue, create acute environmental problems both in terms of their treatment and
disposal. The construction industry has been identified as the one that absorbs the majority of such
materials as filler in concrete. In Ethiopia we have enormous amount of coffee husk and Sugar
cane bagasse ash. However, the utilization of this Coffee husk ash and Sugarcane bagasse ash
waste in concrete production provides significant benefits in terms of reducing construction costs
as well as greenhouse gas emissions.
This research was therefore, amid to examine the potential of combination of coffee husk ash
sugarcane bagasse ash as partial replacement for Portland Pozzolana cement (PPC) in C-20/25
concrete production with investigation of optimum ratio of replacement and engineering
properties of C-20/25 concrete.
Control and three different concrete mixes were prepared for 25MPa concrete containing 5%,
10% and 15% hybrid of CHA&SCBA replacement of cement. Workability of fresh concrete using
slump and compaction factor test and compressive test, split tensile strength test and flexural test
were performed.
From the research, it was observed that the addition combination of coffee husk ash and sugarcane
bagasse ash reduces workability of wet concrete. The results harden concrete work have shown
that, up to 10% replacement of the hybrid of CHA&SCBA achieved a higher compressive strength,
split tensile strength and flexural strength at all test ages i.e. 7, 14, and 28 days of age by test.
It can therefore, be concluded that 10% replacement of cement by hybrid of coffee husk ash
sugarcane bagasse ash results in a similar concrete properties with control test and it is the
optimum replacement
