Addition of bio based reinforcement to improve workability, mechanical properties and water resistance of earth-based materials

Abstract

Large amounts of natural materials are used all around the world to stabilize, to protect from water or to enhance mechanical properties of earth-based building materials. Of these materials are;  alginate, tannins, oak seed extract, cellulosic glue, natural fibers washing water, casein, linseed oil and citric acid. These additions induce different mechanisms at the microstructural scale of earth-based materials and have an influence on their rheology, water sensitivity or mechanical properties. This study will focus on 4 kinds of fine soils that come from the same region (Brittany) and are composed of different varieties of clay and different contents of sand, silt and clay.

The influence of the natural additions on the rheological properties of 4 types of soil will be determined using the penetration cone test (Atterberg limits). It will be compared to the obtained results with the addition of Sodium-hexametaphosphate that acts as a strong dispersant for clay particles. Then the effect of these additions on mechanical strength in the dry state will be highlighted, especially for soils that are made of low specific surface’s clay (such as kaolinite). The influence of the amount of water on the mechanical strength of the earth-based sample will also be determined for each addition. Finally a water absorption test on different dry samples of earth combined with these natural additions will be assessed to show their capacities to enhance the water durability of earth-based materials.

This study shows that natural additions, combined with contained process methods, can be a good alternative to hydraulic binders in order to stabilize earth-based building materials.