Plant-based admixtures for cement-based materials

Water reducers are gaining widespread use due to their ability to enhance concrete workability and lower cement content. They are however predominantly derived from petrochemicals and hazardous substances that pose environmental, occupational, and health risks during manufacture, use, and disposal. This study investigates environmentally friendly plant-based alternatives to conventional water reducers with the aim of developing a more sustainable and commercially viable admixture for cement-based materials. The study focuses on plant materials such as tree gums and tea leaves as well as by-products from agricultural industries such as grape pomace and olive pomace. This study also employs basic extraction methods to reduce energy consumption and costs. Mortar, rather than concrete, is used to isolate the effect of the admixtures on the cementitious matrix. The performance of these plant-based materials is compared with that of commercial water reducers to evaluate their influence on the fresh, hardened, and durability properties of mortar at various dosages. By providing baseline data on the behaviour of plant-based admixtures, this study contributes to the advancement of sustainable construction practices and supports the United Nations Sustainable Development Goals related to industry innovation and responsible consumption. The results show that water-based solutions of tree gums, grape pomace and olive pomace can all increase the flowability and workability of mortar mixes equally or better than commercially manufactured water reducers used at low dosages. Furthermore, Rooibos tea and grape pomace can significantly enhance the strength of mortar. The possible components in plant-based materials that contribute to mortar’s properties are carbohydrates and phenolic compounds, specifically those containing catechol and pyrogallol units. It is possible that if slight alterations are made to the Standard preparation method used in this study such as a slightly higher microwave energy and if different plant-based materials are combined, such as Rooibos tea and red grape pomace, that further improvement can be seen in the fresh, mechanical and durability properties of mortar.

Grantor dc:publisher

Stellenbosch : Stellenbosch University

Year dc:date.issued

2026

Author dc:creator

• Van Wyk, Carla

Advisor dc:contributor.advisor

• Combrinck, Riaan

Language dc:language.iso

en

Repository record dc:identifier.uri

https://scholar.sun.ac.za/handle/10019.1/135645

OAI identifier oai:identifier

oai:scholar.sun.ac.za:10019.1/135645