Published on Nov 30, 2023
Roads are vital for the economic growth of a country. Keeping balance between performance and cost of the roads and at the same time fulfilling the environmental regulations is becoming a challenge for public and private sector. Engineers often face the problem with soft soil like clay soil or black cotton soil which does not possess sufficient strength to carry imposed loads. India consists of 30-40% of black cotton soil of its total area, Black cotton soil is widely spread in North Karnataka, Maharashtra, Gujarat and Madhya Pradesh which has high clay content, low strength and minimum bearing capacity. Because of scarcity of good quality sub grade soil, engineers are forced to design the road with poor engineering properties of soils, by improving the Engineering properties (Stabilizing), without compromising performance, cost effectiveness and eco friendly. Traditionally used soil stabilizers (lime, cement and bitumen) are becoming costly. Gravel and sand which are introduced to alter the soil properties are depleting and increasingly expansive.
This scenario has led to discover the other possible ways to satisfy the performance as well as economical criteria for the stabilization of the soil. Recently bio-enzymes have emerged as a new chemical for soil stabilization and it is popularly available revolutionary technique which is becoming popular worldwide. Recently there are many bio-enzymes available for soil stabilization such as renolith, perma-zyme, terrazyme, Fujibeton etc. These enzymes have been proven to be very effective and economical. Another advantage of the bio-enzyme is that these are environment friendly. One such bio-enzyme, Terrazyme, is selected to use for stabilization of the soil, and to study its effect on the soil with different dosage. The tests studied on BC soil with different dosages of stabilizers are UCS, FSI and CBR.UCS and CBR values have significantly increased with addition of (Terrazyme+ bagasse ash +lime) for dosage of 300 ml/cum when compared to the addition of Terrazyme only. Similarly FSI values has significantly decreased with addition of (terrazyme +bagasse ash+lime) for 300 ml/cum when compared to the addition of terrazyme only.
Keywords : Soil Stabilization Bio-Enzyme (Terra-zyme) Bagasse ash Lime UCS – Unconfined Compressive Strength FSI – Free Swelling Index Durability IS – Indian Standard IRC – Indian Road Congress
• Evaluate effects of additive on preliminary properties (UCS ,CBR and free swelling index) of soils.
• To study the strength behavior of Black cotton soil by UCS test by addition of different dosage of terrazyme ,bagasse ash and lime.
• To study the change in CBR ofthe soil by addition of terrazyme, bagasse ash and lime.
• To study the volumetric change in soil by Free swell index due to addition of different dosage of terrazyme.
• To determine optimum amount of a stabilizer based on various laboratory performance tests.
Collection of material
Black cotton soil
Terrazyme, Bagasse, Lime
Standard Proctor Test
Atterberg Limits
Sieve Analysis
Specific Gravity
CBR
UCS
Index
pH Value
CBR
UCS
Free swell index
Durability
The soil sample untreated and treated with different dosage of Bio-Enzyme and combination of Fly-Ash and Bio-Enzyme could not with stand wet and dry cycles. They collapsed as soon as placed in water bath.
The black cotton soil is tested with all the physical parameters like Atterberg limits , free swell index, CBR, UCS etc and this soil is classified as clay loam soil as per textural classification.
As per the Highway Research Board classification it is classified as A-7-5 properties.
The CBR value of the BC soil increases with the addition of terrazyme +bagasse ash+lime. The increase in CBR value is an indication of higher compressive strength of a soil, better for construction of pavements.
Swelling potential of the BC soil decreases with an increase in dosage of terrazyme. It is minimum mainly at 300 ml/cum of soil which indicate low permeability.
Addition of mixture of stabilizers (terrazyme +bagasse ash +lime) to the soil increase the unconfined compressive strength (UCS). This indicate higher strength of a soil which is good for the construction of highways.
Based on the different laboratory performance tests, it can be concluded thatTerrazyme (eco friendly)+bagasse ash +lime can be considered as a potential stabilizers for clay and silty sand like Black cotton soil. It helps to improve compressive strength of soil. In addition swelling potential of soils decrease with addition of terrazyme making this additive to be suitable for construction of pavements.
Carry out the UCStest for lower dosages of Terra-Zyme i.e. 50ml/m3, 150ml/m3, 250ml/m3, 350ml/m3 and 450ml/m3.
