Influence of fiber on unconfined compressive strength of raw earth material by mix design

Abstract

Building construction technology using raw earth material is already known and used since ancient times. The raw earth material is low cost, abundant, requires very low energy to manufacture and does not generate waste. Thanks to such advantages, raw earth material is used in various construction sites all over the world. This eco-material of the future, may eventually be a good alternative to cement concrete, which is very energy-intensive in terms of gray energy.

The shrinkage and swelling can cause cracks in raw earth material. To minimize the cracks, either natural or synthetic fibers have been included in raw earth materials. Then, a raw earth treatment by binders and vegetal fibers is one of the techniques applied to improve strength and ductility. In this research work, the statistical combinations of five-component mixtures composed of fiber, lime, Portland cement, water and silt, were formulated with a D-optimal mixture design to evaluate how fibers affect the raw earth material. The effect of fibers in raw earth material was evaluated in term of the Unconfined Compressive Strength (UCS). Economical, ecological and workability constraints are considered to set up a mixture design.

The purpose of this paper is to study the influence of flax fibers on the unconfined compressive strength of a raw earth material. In that goal, the design of experiments has been used to establish model formulations targeting the sought strength after 28 and 90 days curing-times. The obtained results indicate that the mixture design approach can be an important tool to study the effect of fibers on the unconfined compressive strength of raw earth materials consisting of several components.