The decreasing availability and increasing cost of construction materials and uncertain economic climates force engineers to consider more economical methods for building roads. An obvious solution is to use locally available materials. However, all too often, these materials fall outside of required specifications. This situation becomes even more critical when an increasing demand for roads in underdeveloped rural areas and informal settlements comes into play.

Likewise, there are increasing pressures on the mining, forestry and agricultural industries to minimize the production costs of their roads while delivering optimum performance and low maintenance costs. An economically feasible solution for achieving these objectives is the use of enzyme soil stabilization.

Nature Plus, Inc. is a basic fermentor and formulator of soil treatment products that create enzyme stabilization of base and sub-base soils used in road construction. We have found from our extensive worldwide experience that enzyme stabilization is effective when the soil contains a sizable fine-grained component. Little if any improvement is achieved in clean sands or gravels. In a study of the performance of over 40 miles of road surfacing stabilized with enzymes, the US Federal Highway Administration found that the best performance was obtained with well graded aggregates mixed with higher clay contents (5% to 15% <0.002mm). Roads treated with TerraZyme experience a cation exchange effect, a clay-water effect and an enzyme stabilization effect.

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TerraZyme soil stabilization products are also designed to improve soil strength by increasing the density of initial compaction and facilitating the removal of pore water, which minimizes the destructive impact of water under conditions of loading. Combined with the impact of TerraZyme on the electrical double layer of clay particles, these factors can promote the formation of a stabilized soil structure of superior density and load bearing strength even in soils lacking a significant plastic fines fraction.

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Field results indicate that soil treated with TerraZyme can reach 95% Modified Proctor with significantly reduced compaction effort. These superior initial densities correlate with lower void percentages in the treated and compacted road layer. Higher densities and reduced percentages of voids indicate that realignment of soil particles may have occurred during compacting, thus allowing treated soil particles to achieve closer proximity and higher strength.

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The reduction in voids resulting from this realignment decreases pore water within the treated road layer and inhibits water penetration. This impact of the TerraZyme treatment process on soil structure correlates with observed reductions in permeability.

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