What insights can Cement Bamboo Frames glean from vernacular bahareque?
A comparative study of lateral load resistance and LCA

Abstract

Introduction In the midst of a climate and housing crisis, the Cement Bamboo Frame (CBF) technology developed by the BASE Bahay Foundation in Manila, Philippines, stands out as an affordable, resilient, and climate-adjusted social housing alternative. This shear wall features a timber and large-diameter bamboo frame onto which a rib lath matrix is a xed and subsequently plastered with cement. Drawing inspiration from the vernacular bahareque technique, this project seeks to enhance the CBF technology with two modifications that are to mitigate the environmental impact. Firstly, the conventional matrix is exchanged with a vernacular flattened bamboo mat, resulting in the Cement Bamboo Shear Wall (CBSW) typology. Additionally, an earth plaster inspired by vernacular practices is introduced, giving rise to the Earth Bamboo Shear Wall (EBSW).

Methodology A comparative analysis of the CBSW and the EBSW, with a specific focus on lateral-load resistance and Life Cycle Assessment (LCA), was conducted. Monotonic and dynamic tests were employed as foundational methods to elucidate the behavior of the walls and derive the desired mechanical properties. Simultaneously, the environmental performance of both wall types was quantified through a LCA, encompassing considerations such as biogenic carbon content and costs. The results were then juxtaposed against the properties of the Cement Bamboo Frame (CBF) highlighting the benefits of the underlying bahareque technique.

Results A noteworthy divergence in failure modes became apparent between the CBSW and the EBSW. This distinction significantly influenced the derived design values. The extracted mechanical properties revealed that both shear wall typologies exhibited commendable strength, stiffness, and ductility, with design values aligning with the standards proposed by the Colombian norm. Confirming their regenerative nature, both the CBSW and the EBSW demonstrated carbon negativity during production. Moreover, the comparative analysis across the various shear wall typologies allowed for the identification of the contribution from the frame, the matrix and the plaster within the composite system.
Conclusion It becomes evident that by incorporating the vernacular bamboo matrix and earth plaster, the environmental performance of the Cement Bamboo Frame (CBF) can be significantly enhanced, all while maintaining mechanical properties within acceptable limits.