Soil Binder Solutions

Soil binder solutions are needed for stabilization of soil which is aimed to be base for roads and buildings.

Soil stabilization is any process by which the soil properties for construction purposes are improved. These can be physical processes such as compaction and drainage, or chemical processes in form of binding soil particles together. If chosen right soil binder solutions, chemical stabilization can show superior properties over the physical stabilization.

Portland cement and lime are the main chemical stabilizers worldwide although they have sincere drawbacks. The main problem with cement is poor ability to contract and expand freely without breakages and thus cracks occur in cement treated terrains and become larger over time. This imposes high maintenance costs. Stabilization with cement incorporates complex and hardly controllable processes. It requires thorough control of soil content, water addition, compaction, etc. Lime is not applicable to many soil types which greatly limit its application. Quicklime is considered the best among lime soil stabilization products but as it is available in powder form, lime dust is generated during application. Environmental impact of lime and cement as soil binder solutions is negative due to extremely high carbon footprint.

Some other common soil binder solutions are fly ash and cement kiln dust, but the same as lime, they are water soluble. Therefore, they lose their effectiveness when precipitation occurs and thus are not suitable for many regions. The problem rises even more if the stabilizers contain harmful substances, which is usually the case for fly ash and cement kiln dust.

While developing soil binder solutions Global Road Technology’s specialists had an aim to create economically and environmentally efficient products. Consequently, highly effective agents compatible with most in situ materials are developed.

The example is GRT7000. It is liquid polymer that can act as a polymer sealant as well as a stabilizing agent.

This polymer is suitable for even highly problematic soils such as black vertosols which exhibit the shrink/swell clay characteristics. The testing results of this soil type treated with GRT 7000 indicated soaked Californian Bearing Ratio (CBR) improvements of 5 to 10 times, significant gains in cohesive strength and large improvements in soil impermeability.

DCP results recorded in all weathers, wet and dry, indicate that the natural subgrade, being black cotton soil maintains a constant state where shrink swell potential, a problematic trait of black soil is controlled as desired. The treated layers above the subgrade that provide the backbone of the road are also performing beyond expectations where the correlation to the CBR is greater than > 60%.

Results indicated that a bearing pressure beyond 2000kPa could be applied without failure. By applying an Australian Standard safety factor of 2.5 to this result provides a certified working platform of 800kPa, enabling it to safely withstand the greatest of applied loads during traffic, and short-term static loads during the most demanding of construction processes consistent with mobile cranes and similar equipment.

Soil strengths beyond 8 MPa can be achieved with as little as 1 % of GRT7000, while an additional increase in polymer content to 3 % resulted in a UCS of 14 MPa. Comparative UCS results in cement stabilised type 2 gravels, require in excess of 5 and 6 % cement by mass. Linear shrinkage testing of the polymer modified blended Type 2 gravel showed a reduction in plastic behaviour.

Due to wide applicability and extraordinary results achieved with small concentrations, GRT 7000 is more effective and economical than conventional soil binder solutions.

For more information on soil binder solutions or Global Road Technology products please contact GRT.