Civil Engineering

Civil Engineering

Lime improves the workability and mechanical performance of soils for rail tracks, roads, highways, hydraulic works, airports and industrial platforms. Hydrated lime contributes to the durability of all asphalt structures, like roads, highways, walkways, etc.

Proviacal
Asphacal

Lime for soil treatment in earth works

Improvement

In the presence of water, quicklime spontaneously hydrates to form calcium hydroxide. The heat released during this reaction rapidly dries out damp soil. Lime also dissolves the clayey particles in the soil into their component parts, and forms pozzolanic cements by combining calcium with the silica and alumina from clays. 

Our quicklime Proviacal® products provide long-lasting improvements to soil’s mechanical performance, improving resistance to traffic and adverse weather conditions. It supports effective on-site usage so you can construct embankments, platforms and pavement layers for roads, railway tracks, airports, warehouses, etc. using local soils at low financial and environmental cost.

Stabilization

By adding the appropriate quantity of lime to soils which are suitable for lime stabilization, the engineering properties of these soils can be upgraded.  Soils from temperate to tropical regions (including lean to fat clays, lateritic to non-lateritic classifications) can be stabilized permanently using lime.  

The improved engineering properties include:

  • reduced shrink – swell (volume change) potential,
  • increased compressive, tensile and flexural strength
  • increased stiffness or resilient modulus.

These enhancements improve the performance of the lime-treated layers in the pavement system. The stronger, stiffer and more volumetrically stable lime treated subgrade, subbase or base layers provide protection for weak and deformation-susceptible natural subgrades.  The result is,  better support for unbound aggregate bases and asphalt surfaces, which enhances their performance.

Our Proviacal®product

  • reduces the extraction of primary aggregates
  • eliminates disposal of excavated soils
  • decreases work site traffic by up to 95%, saving the local road network
  • reduces construction times and costs.

With our very low dust emission quicklime Proviacal® RD, soil in urban areas can be more easily treated. To deal with clayey soils in dry climate conditions, we have also developed products in liquid form.

Quicklime improves soft soils in the deep soil stabilization process (lime-treated columns), reducing settling and increasing stability.

Hydraulic road binders

Lime valorizes and speeds up the reaction of puzzolanic raw materials (fly ash, cement, slags, etc.). Hydraulic road binders comppsed of a significant amount of lime are used for a wide range of soils as they offer greater flexibility in terms of soil quality. They combine the water reduction of the natural soil with the hydraulic reaction of the puzzolanic raw materials.

Hydraulic binders in which lime is incorporated create high performance foundations for roads and rail tracks.

Trenches

Earthwork activities, trench cutting and roadwork excavations produce spoil or aggregates which are often dumped. Environmental regulations and cost pressures seek to limit this landfill disposal and the associated heavy truck traffic. We have developed both dry and liquid solutions to enable the reuse of excavated soil on site by making it suitable for backfilling or road construction.

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Dry process

We have developed a solution that enables onsite upgrading of excavated soil on sites. It comprises a dry treatment process that involves the mixing of dosed quantities of Proviacal® DS (usually 0.5% to 3% by dry weight of soil) to render the resulting material suitable for conventional backfilling and compaction. Lhoist has proven logistics arrangements for just-in-time deliveries. We can also recommend to the best mechanical equipment for soil treatment (mobile units and fixed installations) for specific applications. 

Liquid soil

Lhoist has developed Proviacal® LS RSS-FB that treats and conditions excavated soils to allow their reuse as backfill material. In cooperation with PROV mbH (Leipzig, Germany), we have developed a formulation that combines Proviacal® LS RSS®-FB with excavated soils, a hydraulic component, a mineral clay compound and water. The resulting RSS® Liquid Soil is temporarily flowable and self-compacting. It makes pipe placement in trenches much easier. Compaction time, cost and the need for additional equipment are also reduced and pipes are less likely to be damaged. The lifespan of the sewer lines is increased substantially by the use of liquid soil.

Recycling

Lime improves unsuitable and heterogeneous by-products from excavations. They can then be used to backfill trenches and other urban excavations. This process can be implemented in situ, close to the site or in a central plant increasing resource efficiency. It therefore enables conformance more readily to new sustainable environmental policies.

To optimize the use of lime and facilitate recycling, a proprietary on-site system developed by Lhoist allows lime to be dosed directly from big bags/super sacks into a screening bucket.

Aggregate improvements

Proviacal® improves aggregates using a dry technique rather than a washing operation (with all its inherent disadvantages). Some quarried materials and/or recycled products contain useful aggregates, but they are difficult to process in the crusher/screener due to their extremely sticky clay content. As a result, they are removed at the primary crushing stage. The processability of such clay-clogged materials is even more difficult in wet conditions (see pictures before and after treatment). Proviacal® produces better aggregate quality which makes them more valuable in the market. It also results in a higher yield of commercialized quarry output. Proviacal® products are available in powdered form. They can be delivered in bulk or in big bags/super sacks.

Suitable mixing equipment can be installed to complement or complete existing quarry primary crusher/screener processing units (fixed or mobile). With Proviacal®, material flow is simply side-conveyed to the mixer, after which it rejoins the usual process route. Together with external partners, we have developed different types of mixing equipment to treat, recycle and upgrade difficult materials. The lime-enriched parts of these materials, after screening aggregates, can be used as an ideal filling material that features excellent mechanical compaction properties.

Tunnels

Mortars 

In tunnel construction, in addition to the calcium that is used as filler, hydrated lime (Proviacal® BT) improves the rheology of mortars, reducing the amount of expensive special organic additives required and lowering the cost of grout formulation. It also creates binders for injection works.

Dredging sludges

Quicklime dries out the drilling mud that comes from excavation process, making handling easier. It improves soft soils, reduces settling and increases stability.

Synergies between clay and lime provide opportunities for recycling.

Hydraulic works

Proviacal® DD, our lime-based product for hydraulic works, such as dikes and dams, is proven to improve erosion resistance while maintaining soil permeability. The enhanced workability and mechanical stability of wet and clayey treated soils helps reduce financial and environmental costs. 

Landscaping (hydraulic engineering)

We produce large stone sizes from many of our quarries that are used for decoration. In hydraulic engineering, they control erosion of riverbanks and reduce drainage from lakes.

Asphalt

Asphacal®, the solution for longer-lasting roads

As a road manager or professional in the paving industry, you are always looking for new long-lasting and economical techniques to build roads and walkways. Lhoist has created the Asphacal® line of products for hot and cold mixed asphalts used for road construction and maintenance.

Asphacal® H

Asphacal® H is a hydrated lime product that improves the performance of asphalt mixes in roads and pavements. Tailor-made mixtures with fillers are also available. They require no modification of the dosing installation at the customer site. Improvements to asphalt quality in terms of resistance to water stripping, frost-thaw cycles, de-icing salts, age-hardening and rutting are the result.

Hydrated lime added to asphalt mixtures has been proven to increase pavement durability by 25 % or more.

Asphacal® TC

Asphacal® TC prevents tack coats from being damaged by construction traffic (tires and caterpillars).

Tack coat integrity needs to be preserved to:

  • ensure the durability of the road structure; it has been proven that lack of adhesion between asphalt layers reduces durability by up to 5 times.
  • keep the area around the job site clean, leaving construction equipment and neighboring road markings free from bitumen marks.

Road authorities’ studies have shown that the impact Asphacal® TC has on the adhesion of tires maintains bonding between road structure layers.

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