Impact of clay on infrastructure

 
Certain types of clay minerals (montmorillonite) within clay soils have the potential to adsorb large amounts of water into their mineral structure due to the very weak bonds between the adjacent silicate sheets. Given an abundance of water, clay soils will swell and increase in volume. The likely magnitude of volume increase is directly related to the plasticity of the clay, with high plasticity clays showing greater volume change potential due to the fact they contain a greater proportion of montmorillonite.
 
Shrinkage is caused as water is lost from the soil via suction forces, which is due to evapotranspiration from the soil to the atmosphere which is facilitated by plants, bushes and trees as well as by the structure of the clay soil itself. The process of evapotranspiration primarily occurs in the spring and summer, when plants and trees are growing, which causes clay soil to shrink and then to swell in the autumn and winter when the recharge from rainfall replenishes the summer water deficit.
 

This issue impacts all types of infrastructure

Rail

On rail networks the shrink-swell behaviour of high plasticity clays can cause significant differential movement of the sub grade on which the trackbed is constructed. These differences in level caused by the shrink-swell behaviour compromise track stability and alignment causing [track faults] which are significant safety risks. The immediate solution to this are emergency speed restrictions, which lead to long delays and a substantial impact on the operational schedule, which have substantial consequential financial impacts.


Railway Embankment

Railway embankments constructed of reworked high plasticity clay are particularly vulnerable to shrink-swell behaviour, with differential movements not only affecting the sub grade on which the trackbed is constructed but also the slopes of the embankment which can destabilised and degraded by decades of seasonal shrink-swell behaviour.

infra case study svr

 

Infra highwasy pavement cracks

 

Buildings and Structures

The foundations of buildings, bridges, bridge abutments, retaining walls, and other critical assets which are cast in high plasticity clays are also at risk from differential ground movement caused by clay shrink-swell behaviour.

Roads

The shrink-swell behaviour of high plasticity clays can also cause differential movement of  the sub grade below the pavement construction layers which support roads and highways. This causes loosening and potentially voiding of the previously compacted construction layers; which manifests as cracking of the surface wearing course. This cracking can develop into potholes and other surface defects which can damage vehicles and cause safety hazards. The traditional solution to these defects would be to either patch the road or relay the surface causing major disruption and delays  to road users.

Utilities

Buried utilities like water pipes, gas lines, and electrical cables are highly vulnerable to differential ground movement, such as that caused by clay shrink-swell behaviour.  The  movement, if large enough, can shear pipes and cables, causing leaks, bursts, and widespread service interruptions.

Business & Community Impact

The consequences of clay shrinkage and swelling are profound for infrastructure managers. The likelihood of extreme shrink-swell behaviour of clays soils is linked to high and prolonged soil moisture deficits, which are entirely unpredictable in nature. Consequently, the required repairs to maintain infrastructure integrity are most likely to be unbudgeted. Beyond the financial cost, failures lead to service disruptions that directly impact the community, from traffic jams caused by road closures to travel chaos from rail delays. Unexpected service failures can also pose a serious risk to public safety.

At Geobear, we act as a responsible contracting partner, helping solve these problems without the need for disruptive, time-consuming excavation. Our solutions are up to 70% faster than traditional methods, helping you maintain operations and get infrastructure back in service quickly and safely.

Traffic jam

 

What is Geobear's clay solution?

Geobear's Clay Shrinkage Treatment is an ideal, non-excavation alternative to traditional methods. Instead of constructing new deeper foundations or replacing loosened material above the subgrade by excavation or retamping railway trackbeds, we use geopolymer injection to stabilise the ground from below. Our non-disruptive method has a number of benefits:

1

Improves the ground

Our geopolymer method stabilizes the clay sub grade on which infrastructure assets are constructed. It does this by reducing the rate at which moisture can be lost from or entering the soil by reducing the bulk permeability. In addition to this it greatly reduces the ability of trees and other plant roots from removing water from the soil.

infra a323 injection tubes
2

Is up to 70% faster

Our solutions can be completed in hours or days, not weeks or months. This dramatically reduces downtime, helping you protect your operational integrity.

Geobear team injecting geopolymer while checking laser level measurements
3

Has a 75% lower carbon impact

Our approach is significantly more sustainable than digging and replacing soil, helping you meet your environmental commitments.

CO2 assesssed
4

Offers a wide portfolio of expertise

We have a proven track record as a contracting partner, with our teams and engineering expertise available to support you on projects of any scale. For issues requiring significant load transfer, we also offer a structural support treatment.

Geobear employees standing for a group photo on a sunny day

Contact Geobear

To discuss a site affected by clay shrinkage, contact us today.

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