Influence of bacterial cellulose stabilization on strength characteristics of construction earthen materials

The interest of reinventing raw earth is for the purpose of drastically reducing the environmental impact of the continuous human urban growth. This paper discusses the use of cellulose synthesized by bacteria as a new source of microfibers to reinforce the soil matrix. It presents firstly, the bacterial cellulose (BC) and its production method then it focuses on defining its microstructural characteristics. In the second part, the soil-BC association is studied. Commercial soil (DW-earth) and bentonite clay were tested with 3 and 8% of BC. The objective is to evaluate the impact of BC addition on the soil’s physcio -mechanical properties. Shrinkage and mechanical performance tests were carried out. The results showed a material with better mechanical performances and high cracks resistance. The shrinkage percentage decreased significantly for DW-earth with a similar water/solid ratio when adding BC, by about 18 and 22% when adding 3 and 8% BC for water content of 35%. In the case of bentonite clay the BC addition has only a positive impact on limiting cracking. The mechanical tests showed that 8% of BC increases the compressive strength of the cylindrical specimens by + 28 and + 649%, respectively for the DW-earth and bentonite clay, whereas the flexural strength of the prismatic specimens increases by + 39 and + 556%.