MIX DESIGN AND SAMPLING

 Identifying a suitable source for earth is just the first step in an important process. Many other factors will affect the appearance and performance of earthen walls.  Most such walls in North America will require added stabilizers either for climactic reasons or to satisfy engineering specs. Regardless of the type of stabilizers used, proper batching is critical. Ideally a thorough analysis of the clays found in the source material will factor in to the amount of stabilizer called for. It is not uncommon to achieve equal or even higher compression test results with lower amounts of added stabilizer, which has the added benefits of reduced cost and smaller carbon footprint. Sample preparation and testing for a range of stabilizer percentages is the surest way to determine the optimum ratio. Other possible additives to the mix include pigments, supplemental aggregates, different soil blends and admixtures for the control of efflorescence. Best practice would dictate that samples submitted for conformity to specs (both cosmetic and compression) include all component elements of the finished wall mix and batching ratios which can be accurately scaled for use in the field.