Contractors and Engineers don’t always work in ideal situations. So what they need are ideal solutions. Carmeuse answers the call with lime products for Soil improvement and Subgrade Stabilization.
Lime for Soil Improvement and Subgrade Stabilization
Wet, weak, fine grain soil can prove to be a major challenge at many construction sites. Muddy site conditions make for difficult working conditions. Access is difficult for construction vehicles. It’s difficult to reach the soil moisture and compaction requirements established by the project civil or geotechnical engineer. Wet, poorly compacted soil makes for poor pavement support and embankment/fill. At a construction site, lost time means lost money.
Lime quickly improves the soil condition during construction and can add long term improvements to key soil properties. Adding lime can cause three major soil improvements:
- Soil Drying – Reducing the soil moisture content
- Soil Modification – Reducing soil plasticity, aiding compaction and increasing early strength
- Lime Stabilization – Increasing long term strength and reducing swell potential
Lime can be used to stabilize pavement subgrade soil containing clay. Lime stabilization generates a long term pozzolanic strength-gaining reaction between lime and the silica and alumina minerals solubilized at high pH from the clay, forming calcium silicates and calcium aluminates. If the subgrade soil or aggregate base lacks suitable reactive clay, it is advantageous to add a coal fly ash pozzolanic material along with the lime.
In addition to the benefits provided by lime modification, the benefits of stabilization include:
- Greater strength improvements than from soil modification.
- Increase in CBR penetration resistance and resilient modulus stiffness.
- Freeze-thaw resistance.
- Long-term retention of strength improvements.
As a general rule, authorities on soil stabilization recommend that lime be considered for all soils when the plasticity index exceeds 10 and the percent of soil smaller than the #200 mesh sieve exceeds 25%.