Endurazyme / Lime / Rice husk ash blend.

Black laterite soils in Indonesia.

Much research has been done to into the problem of soils high in fines and plastic index in areas that have no gravels available within reasonable reach.

Over the years waste materials such as fly ash or pozzolanic materials have been used for soil improvement. Recent research, based on pozzolanic activity, found that rice husk ash was a potential material to be utilized for soil improvement.

When the mechanical stability of a soil cannot be obtained by combining materials as in proportional mix design, it may be advisable to order stabilisation by the addition of cement, lime, bituminous material or special additives [Endurazyme]. Cement treatment is most applied to road stabilisation especially when the moisture content of the sub-grade is very high. Lime or waste is also sometimes applied for stabilisation.

Calcium hydroxide (slaked lime) is most widely used for stabilization. Calcium oxide (quick lime) may be more effective in some cases, however. The quick lime will corrosively attack equipment and may cause severe skin burns to personnel. Ingles (1972) recommended.

Rice husk ash (RHA) is a pozzolanic material that could be potentially used in Indonesia, considering it is sufficiently produced and is widespread. When rice husk is allowed to burn under controlled temperature, higher pozzolanic properties than other leaf plants were observed. Silica is a main mineral of RHA. When reacted with lime, it will form a bonded gel [Ca(SiO3)]. Silica fume can used as a cement replacement with great success.

By using a mix of Endurazyme / Lime / Rice husk ash [RHA] it is feasible that large increases in strength will be achieved plus Endurazyme will increase the impermeability ensuring that the Lime does not leach out. The lime and RHA will help in dewatering wet soils and sub-bases and decrease the curing time for the total pavement or embankment this is especially important in Indonesia and most Asian countries.

Lime reacts with any other fine pozzolanic component (such as hydrous silica and RHA minerals) to form calcium-silicate cement with soil particles. This reaction is also water insoluble. The cementing agents are exactly the same for ordinary Portland cement. The difference is that the calcium silicate gel is formed from the hydration of anhydrous calcium silicate (cement), whereas with the lime, the gel is formed only by the removal of silica from the clay minerals of the soil. Therefore, it can be concluded that Endurazyme, lime and rice husk ash (ELRHA) can improve the engineering properties of soils. Practically, the effective lime content should be blended in the range of 2% to 6%Lime and 4% to 10% Rice Husk Ash.

Results From Research By Agus Setyo Mantohar and Gendut Hantoro .

The results from the LHRA (lime-rice husk ash) blend confirmed that the blend would diminish swell behaviour of clayey soils. Their PI (plasticity index) would decrease from 41.25% to 0.96% when subjected to a LHRA blend of 12-12.5%. Their swell potential would decrease from 19.23% to 0.019% when subjected to the same blending as well. Their CBR (California Bearing Ratio) value would increase from 3.03% to 16.3% at a LHRA blend of 6-12.5%.

Their internal friction angle concerning shear strength parameters would enhance from 5.36 to 23.85. Soil cohesion increased as well from 54.32 kN/m2 to 157.19 kN/m2. Increasing the shear parameter caused bearing capacity to be 4131 kN/m2 from 391.12 kN/m2. At LHRA 6-10%, consolidation settlement was lowered from 0.03 to 0.006. All of these factors can be summarized to say that by blending lime-rice husk ash together, you may enhance the engineering properties of clayey soils. This is advantageous for work construction in the civil engineering field.

Conclusion

Lime stabilization is commonly used for clayey soil. This research shows: 1. Physical properties such as consistency limits and swell potential exhibit improvements when mixed with the appropriate ELHRA blend.

2. LRHA stabilization is more advantageous when moisture content of soil in the field is very high or applied in the optimum condition.

3. The engineering properties of soil improve:

a. CBR, and shear strength of soil improve at a lime range of 6 – 10%

b. Consolidation settlement diminishes

c. Rate of consolidation enhances by increasing of ELRHA.

4. Economically, utilization of ELRHA for geotechnical applications is cheaper.

5. Physical properties such as consistency limits and swell potential exhibit improvements when mixed with the appropriate ELHRA blend.

6. ELRHA stabilization is more advantageous when moisture content of soil in the field is very high or applied in the optimum condition.

7. The engineering properties of soil improve:

a. CBR, and shear strength of soil improve at a lime range of 6 – 10%

b. Consolidation settlement diminishes

c. Rate of consolidation enhances by increasing of ELRHA.

8. The engineering properties of soil improve:

a. CBR, and shear strength of soil improve at a lime range of 6 – 10%

b. Consolidation settlement diminishes

c. Rate of consolidation enhances by increasing of ELRHA.

Add to this the efficacy of Endurazyme and we have a working model for high swell high fines soils, including wet soils.