Optimizing HighRange Water-Reducing And Retarding Admixtures: Substituting Gluconate With Sugarcane Molasses For Sustainable Concrete Production In Ethiopia
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Date
2025-02
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Addis Ababa University
Abstract
The construction industry is a critical sector in Ethiopia’s economy, yet it faces persistent
challenges due to foreign currency shortages that limit the import of essential raw materials,
including chemical admixtures. High-range water-reducing and retarding admixtures (Type
G) are widely used in concrete production to enhance workability and setting time.
However, the reliance on imported gluconate as a retarder increases costs and project delays.
This study investigates the feasibility of substituting gluconate with sugarcane molasses, a
locally available by-product of Ethiopia’s sugar industry, to develop a cost-effective and
sustainable alternative. A series of experiments were conducted with varying molasses
concentrations (2.5%–4.5%) in combination with Sodium Naphthalene Formaldehyde
(SNF). Workability was assessed using slump tests at 0, 30, 60, and 120 minutes.
Compressive strength was evaluated at 1, 3, 7, and 28 days, with density measurements
performed on hardened concrete samples. Results showed that increasing molasses content
significantly improved slump retention, with a 60mm increase at 120 minutes when 4.5%
molasses was used. However, early compressive strength (1-day and 3-day) decreased,
while 7-day and 28-day strengths improved, demonstrating molasses' effectiveness as a set
retarder. The findings indicate that molasses can serve as a viable alternative to gluconate in
Type G admixtures, reducing dependence on imported materials and lowering costs. The
study recommends further field trials, optimization of molasses concentration, and policy
support for local admixture production to enhance Ethiopia’s construction sector
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Keywords
Molasses, Admixture, slump value, compressive strength