KALK:

Since ancient times people use lime as a binder for his constructions. The oldest concrete on the basis of lime dating from 5600 BC were discovered in Lepenski-Vir in the Balkans Serbian. The Romans acquired knowledge of ancient civilizations and have perfected it. The most striking example is the dome of the Pantheon in which the concrete was made from lime and puzzolana sands! What would have been the medieval architecture without lime? The Gothic cathedrals, with their pointed arches reaching heaven, are only possible thanks to the flexibility and processability which lime - in particular air lime - offers. The earliest example of soil treatment with lime is the Via Appia, built on a lime stabilized soil, dating from Roman times and still in use. Closer to home was in the '70s and '80s with lime abundant soil improvement used in the construction of many motorways in Belgium. Nowadays, the use of lime for its properties and clay loam soils to improve, is still in full evolution. The development of machinery, research and innovative developments in geotechnical laboratories of the lime industry, this process is again increasing significance. Whether it's for major projects (motorways, high speed trains, airports), or less important projects (car parks, industrial platform systems and local roads), technical, economic and ecological benefits of stabilizing the soil with lime are much appreciated by investors and contractors. The systematic increase in costs associated with the disposal of surplus land and the increased awareness of the environment brings this technique increasingly in the spotlight.

 

The effect of lime.

Mixing a small percentage of lime in a wet, plastic forefront cause both "immediate" as "medium-term responses". Immediate impact: crumbling (soil improvement) and drying (dehydration)!

Crumble: the mixing of lime modifies the electrostatic fields between the clay particles. As a result the particles get a grain structure.

Drying: When mixing lime reacts with moist soil and brings it directly caused a strong heat (exothermic hydration reaction). The result is a reduction of the natural water content of the soil by evaporation and hydration. This dryness is exacerbated by the aeration of the soil while mixing. Depending on the weather, the water content decreases by 2 to 3% per percent added calcium.

 

These two phenomena translate into geotechnical terms by:

• The reduction of the plasticity index. The soil is transferred abruptly from a plastic state (deformation and adhesive) to a solid state (stiff and grainy). In this state it is easier to dig, load, unload, to condense and smooth.

• Improving the compaction properties of soil. The maximum dry density decreases, while the optimum water content increases so that the soil moisture comes in an area where a good compaction is possible. This effect is clearly an advantage when working in wet grounds, something that in The Netherlands is often the case. Using lime allows a plastic, sticky and difficult condensable soil, to be formed into a stiff , grainy and easy to use constructing material in only a few minutes. Once treated and compacted, the soil has an excellent bearing capacity and accessibility.

• Increasing the baring capacity. In most cases, the CBR index (Californian Bearing Ratio index) of a treated soil, is 2 hours after treatment, already 4 to 10 times higher than that of an untreated soil. This reaction increases the direct transportation opportunities at a construction site.