Conducted jointly by INC-CNRS and UL, this research explores the use of rattan and rônier palm in laterite concrete.
Key Takeaway: Conducted jointly by INC-CNRS and UL, this research explores the use of rattan and rônier palm in laterite concrete.
Yémalin Agossou, researcher at IJL (Institut de Chimie - CNRS Chimie).
Thesis defended in 2021 at the doctoral school École doctorale C2MP - Chimie mécanique matériaux physique (Lorraine).
This research was conducted as part of a Franco-Beninese joint supervision (cotutelle), ensuring it is simultaneously grounded in local field conditions and international academic standards.
Context and Problem Statement
The construction sector is one of the largest consumers of energy and emitters of CO2 worldwide. This raises critical environmental concerns, particularly the need to develop construction materials with a lower ecological impact. Implementing eco-friendly solutions has therefore become a priority. This thesis explores the potential of a new material, laterite concrete, which uses lateritic aggregates in place of conventional materials and replaces steel reinforcement with plant-based alternatives such as rônier palm (Borassus aethiopum) and rattan (Calamus deariatus).
The integration of these local, renewable materials aims to reduce the carbon footprint of structures while meeting the growing need for housing and infrastructure in West Africa. The study focuses on the physical and mechanical characterization of laterite, as well as the mechanical performance of plant-based reinforcement, in order to establish a laterite concrete that is competitive with traditional concretes.
Methodology
The research was conducted using laterite extracted from the Atotingo quarry, located in the commune of Allada, Benin. The first step consisted of a physical and mechanical characterization of the laterite, followed by the development of a mix-design method for structural concrete based on this material. Three types of laterite concrete were developed, varying the aggregate washing processes to optimize the mechanical performance of the concrete.
Rônier palm and rattan reinforcement were also characterized to determine their tensile strength and bond behavior with the concrete. Compression tests on the concrete were used to measure strength at 28 days, while bond tests were carried out to assess the interaction between the plant-based reinforcement and the laterite concrete.
Key Findings
The study's results show that the compressive strength of laterite concrete can reach 27.52 MPa when the laterite is carefully washed to remove fine particles smaller than 63 µm. This performance is significantly higher than that obtained with raw laterite, which shows a strength of 21.23 MPa.
The plant-based reinforcement displayed interesting mechanical properties, with a direct tensile failure stress of 156 MPa for rônier palm and 22 MPa for rattan. The bond strength between laterite concrete and rônier palm reinforcement was measured at up to 4 MPa, validating the integration of these materials into concrete structural design.
In terms of practical applications, the laterite concrete flooring developed can support spans of up to 3.50 meters, requiring reinforcement with a diameter of 25 mm to comply with current construction standards.
Discussion and Outlook
The use of laterite concrete reinforced with plant-based materials offers notable advantages for sustainable construction. By prioritizing local, renewable materials, this approach not only reduces the carbon footprint of construction projects but also supports the local economy by making use of locally available resources.
These results pave the way for future research on optimizing the mix design of laterite concrete and on the long-term durability of structures built with these materials. Further studies could explore field implementation conditions and the in-service performance of these structures, while incorporating economic and environmental analyses to assess the overall impact of this alternative on the West African construction sector.
Integrating these solutions into construction standards will also require commitment from decision-makers and industry stakeholders, in order to encourage the adoption of sustainable, environmentally responsible practices.
Key Data
- 27.52 MPa: Compressive strength of laterite concrete, comparable to certain traditional concretes.
- 4 MPa: Bond strength between laterite concrete and rônier palm reinforcement.
- 3.50 meters: Maximum span of floors built with this concrete.
Accéder à l'étude complète
Sources and Access
Yémalin Agossou. Étude de la mise en œuvre du rotin et du rônier comme armature des nervures et armatures de paillasse de la table de compression en béton de latérite. Mécanique des matériaux [physics.class-ph]. Université de Lorraine; Université d'Abomey-Calavi (Bénin), 2021. Français. ⟨NNT : 2021LORR0350⟩. ⟨tel-03719709⟩