**3. Royal road product 2-3-5 special (RRP235special) introduction**

The RRP235special has been made in Germany. The additive is acidic liquid and affects clayey soil through the chemical–mechanical process. **Figure 1** shows the RRP235Special with the R symbol and its chemical reaction.

As shown in **Figure 2**, the additive acts chemical process in three stages dissociation, ion exchange, and neutralization. The additive is diluted with water to achieve dissociation. Then, the mixture is pure to the soil, and the exchange of ion starts. The reaction time is different depending upon the type of soil, fine grain fraction, and the chemical elements of the soil. Finally, the neutralization is done by exodus of water.

The soil particles can perform the chemical reaction with water and other elements only when the fine grain fraction is less than 0.06 mm. Large part of soil (sand and gravel) cannot produce a chemical connection with water. So particles smaller than 0.06 have a key role in clayey soil stabilization with RRP235special.

**Figure 1.**

*Chemical reaction of RRP235Special [37].*

**Figure 2.**

*Description of the ion exchange at the colloids [37].*
