How does lime stabilisation work

Second, calcium carbonate is soluble salt and may pulverize when exposed to air for a longer period. Furthermore, carbonation process consumes calcium ions which negatively affects the pozzolanic reaction.

Lime in soil stabilization or any calcium-based additives when in contact with soluble sulphate salt may cause soil distress and heaving, resulting in strength loss. The source of sulphate is either soil minerals, water used for mixing or groundwater. Some other noticed adverse effects are increased soil compressibility and reduced shear strength. To simplify the determination of soil suitability for treatment with certain stabilizer, Global Road Technology invented products which are effective in all soil types.

Furthermore, far lower concentrations of GRT products are needed than lime in soil stabilization. GRT products are available in liquid form and are not reactive, which make them OHS and environment-friendly. The other huge advantage of the use of GRT product instead of lime in soil stabilization is that GRT products have a very low carbon footprint, while the production of lime results in large amounts of CO 2.

For more information on lime in soil stabilization or Global Road Technology products please contact us :. Request Free Quote. As a result, some soils can produce very significant strength gains when treated with lime. The key to pozzolanic reactivity and stabilization is a reactive soil and a proper mix-design protocol. The results of soil stabilization can include very substantial increases in resilient modulus values, significant improvements in shear strength, continued strength gains over time, and long-term durability over decades of service.

Graymont's commitment to this sector continues to grow, as reflected in the recent completion of one of the largest lime transfer terminals in North America specifically to serve the soil-stabilization market in central California.

Graymont's New Zealand facilities are also important suppliers in the roading market specializing in consistent product quality and customized logistics solutions for high volume projects.

For more information, visit www. The cost of importing engineered fill materials and exporting sub-par materials is only increasing. Soil stabilization saves time, money, materials and energy. There are two basic configurations for What is Soil Remediation? Soil remediation is the application of proven technologies to mitigate Lime vs. What is Soil Stabilization? Get back to work with less downtime. Get a quote Lime Stabilization of Soil Why is lime used in soil stabilization?

What lime is used in soil stabilization? Cement Stabilization of Soil What is soil cement stabilization? What is Portland cement? Give me a call at Josh Weser Mintek Resources.

Related Posts. What are Dredge Spoils? Dredge spoils are the sand, soil, silt and other organic matter that However, the most widely used and best performing limes in soil stabilization are the quicklime CaO and hydrated Ca OH 2 lime. Based on this difference, it is therefore important to evaluate ultimate superiority of one over the other in lateritic soil stabilization. This ensures the most appropriate lime source will be chosen during lime stabilization of this soil group.

A wide range of investigations have been conducted on lime stabilization of soils in the past [ 2 , 3 , 9 , 10 , 16 , 17 , 22 , 27 ]. The most notable effect of lime on fine-grained soils is to produce decreased plasticity, increased workability, reduced swelling and shrinkage potential as well as increased strength [ 1 , 6 , 14 , 16 ]. Of these two types of lime, research has shown that more strength development occurs in soil—quicklime mixtures rather than hydrated lime [ 3 , 6 ].

Also, very rapid stabilisation of water-logged sites or very wet materials has been achieved with the use of quicklime [ 3 ].

Hydrated lime on the other hand is used extensively for the stabilisation of soils with high clay content where its main advantage is in raising the plastic limit of the clayey soil [ 2 , 8 ].

Beyond these, it has also been reported that the relative stabilizing effect correlates well with the calcium oxide CaO content of various limes [ 6 , 10 , 17 , 27 ]. The primary chemical reactions that occur when lime is mixed with soil and water are cation exchange, flocculation and agglomeration as well as pozzolanic reactions.

The cation exchange and increased ionic concentration of the pore water results in a contraction of the diffuse double layer, flocculation and agglomeration of particles, and nearly instantaneous reduction in plasticity index PI with improved workability [ 6 , 14 , 24 ].

Another consequence of dissolution of lime is an increase in pH of the soil—water-lime mixture due to the increased concentration of hydroxyl ions. The increased pH causes silica and alumina associated with clay particles to become soluble.

Thus, the lime provides the calcium and a proper chemical environment, while the soil provides the silica and alumina ions necessary to form cementitious compounds i. These clay silicates and clay aluminates bond or gel to the clay particles together to further strengthen the soil. This reaction is dependent on time in the fact that the longer a specimen is allowed to cure, the more the clay reacts with the lime and the higher the strength [ 1 , 14 ].

The objective of this study was to evaluate and compare the stabilization effectiveness of different percentages 0, 2. Performance evaluation experiments included: Atterberg limits, compaction, unconfined compression tests UCT , California bearing ratio CBR , swelling potential using CBR instrument and hydraulic conductivity. All samples were collected in their disturbed state and from a sufficient depth below the ground surface i. It is a natural reddish brown soil Fig. The quick and hydrated limes used in the study are the industrial grade available Fig.

To preserve them from carbonation, each bag of lime was double bagged with black plastic bags that were securely tied. Prior to lime treatment quick and hydrated limes , the soil sample was air dried and pulverized in a crusher to less than 4. In order to stabilize the soil, appropriate amount 0, 2. Atterberg limits of specimens were determined in general accordance with BS and BS [ 4 , 5 ] standard test methods for liquid limit, plastic limit, and plasticity index of soils. Treated soil specimens were delayed for 24 h after mixing before compaction.

Specimens for unconfined compression UC testing were prepared with appropriate dosages of quick and hydrated limes at optimum water content.

The moist room curing minimizes any loss of moisture from sample, while the plastic bags prevent transfer of moisture from outside. Unconfined compression tests were conducted on a strain-controlled triaxial testing frame Fig. CBR tests were conducted on compacted natural lateritic soil and specimens containing different amounts of quick and hydrated limes prepared at the optimum moisture content.

Specimens stabilized with the two types of lime were cured for 28 days in the same conditions as in specimens for UC test. At the end of curing period, the unsoaked CBR of the untreated soil and those treated with quick and hydrated limes was measured. To obtain the soaked CBR values, perforated base plate was attached to the bottom of the CBR mould to allow for the ingress of water during soaking. Specimens were placed in a CBR soaking tank for 96 h.

At the end of 96 h soaking period, CBR of soaked specimens, untreated soil and those stabilized with quick and hydrated limes was measured by a CBR equipment Fig. Specimens for CBR swell test were however, soaked for an extended period of 28 days before measurements were taken to ensure that all swelling has ceased. At the end of this period, calipers were used to measure the change in specimen height.

While the specimens were in the compaction moulds, they were placed in resealable plastic bags and cured for 28 days in the same conditions as in specimens for UC test.

Immediately after the curing, soil specimens were saturated under free-swell conditions by immersing them in water bath. Once swelling reached equilibrium, the saturated soil specimens were subjected to hydraulic conductivity measurements using the falling-head hydraulic system Fig. The measurement was continued until the stabilisation of hydraulic conductivity.

The key characteristics of the untreated natural lateritic soil selected for testing, including Unified Soil Classification System USCS and AASHTO classifications, grain size analysis, and plasticity data, are summarized in Table 1 , while the oxide composition of the lateritic soil used in the study is reported in Table 2. Figure 6 provides information on Atterberg limits of the studied soil treated with the two types of lime and each showed distinct response in modifying the soil. The addition of lime characteristically led to a reduction of liquid limit for both quicklime and hydrated lime specimens.

However, more liquid limit reduction occurred in quicklime treated soil rather than soil sample treated with hydrated lime. Variation in Atterberg limits with lime content for the soil stabilized with quicklime and hydrated lime.

In contrast, the test results show that the plastic limit increased though slightly on addition of the two types of lime. In this case, similar values at the various percentages of the two types of lime were obtained. The overall effect of treatment with lime on plasticity characteristics is a reduction of plasticity index PI of soil mixtures.

Like the liquid limit, the data in Fig. On the whole, increased lime content resulted in increased plasticity reduction. Similar results have been reported by Dash and Hussain [ 10 ], Okoro et al.