Feasibility
Evaluate maize cob ash as a partial cement replacement in sandcrete blocks.
UNDERGRADUATE RESEARCH REPORT
Maize Cob Ash in Sandcrete Blocks
Investigating maize cob ash as a partial replacement for ordinary Portland cement in sandcrete blocks for non-load-bearing walls.
Kampala, Uganda Sustainable construction Materials engineering
Project overview
The study examines whether ash produced from maize cobs can replace part of the cement used to make sandcrete blocks. It responds to two linked challenges: agricultural-waste management and the cost and environmental impact of cement in affordable construction.
The supplied report describes experimental blocks made with a 1:6 cement-to-sand mix, a water-cement ratio of 0.5, and maize cob ash replacement levels of 0%, 5% and 10% by weight. Specimens were cured for 14 and 28 days before testing.
RESEARCH QUESTION
What the study investigates
Can locally sourced maize cob ash be used as a supplementary cementitious material in sandcrete blocks while maintaining suitable performance for non-load-bearing walls?
OBJECTIVES
Research objectives
Replacement levels
Compare control, 5% and 10% maize cob ash replacement mixes.
Strength
Assess compressive strength after 14 and 28 days of curing.
Water absorption
Record water-absorption behaviour as part of the reported testing programme.
MATERIALS AND METHOD
Reported experimental approach
Maize cob ash
Maize cobs sourced in the Ggaba area of Kampala, dried and burned to produce ash.
Sandcrete blocks
Blocks produced with a 1:6 cement-to-sand mix ratio.
Replacement programme
Ordinary Portland cement replaced at 0%, 5% and 10% by weight.
Curing and testing
Specimens cured for 14 and 28 days and tested for compressive strength.
REPORTED FINDINGS
Results in the supplied report
The following figures are reported in the supplied undergraduate project report and have not been independently verified by CBA.
5.0 MPa
Reported 28-day compressive strength at 5% maize cob ash replacement
2.8 MPa
Reported 28-day compressive strength at 10% maize cob ash replacement
0%, 5%, 10%
Reported maize cob ash replacement levels tested
1:6
Reported cement-to-sand mix ratio
INTERPRETATION
Scope and responsible use
Non-load-bearing scope
The report concerns sandcrete blocks for non-load-bearing walls, not structural applications.
Verification needed
The report is presented as undergraduate research. Its findings should be independently reviewed before specification or wider application.
Circular-material potential
The work explores a possible route to recover value from agricultural residue in construction materials.
RESEARCH CONTACT
Kodok Chol Reng Ajak
Researcher on the maize cob ash sandcrete block study.