What Is The Difference Between Cohesive And Non-Cohesive Soils?

by | Dec 8, 2020

For many people, soil is exactly that. The stuff that gets on your children’s new clothes, your Sunday League shorts or your fingers whilst gardening. Most of us don’t give soil much thought beyond it being, well, soil. However when carrying out a ground investigation this isn’t the case. The reality, however, is that soil is far from being some uniform substance, and it can vary in type massively. The team here at Borehole Solutions Ltd, who offers various geotechnical and site investigation services, wanted to look at the difference between cohesive and non-cohesive soils.


Cohesive Soils

Cohesive soils are fine grained soils and are those whose particles aggregate or clump together. In layman’s terms, the stuff that sticks together! These soils are characteristically soft and can hold a large moisture content. Upon drying they obtain almost cement-like hardness. Cohesive soils (largely due to their ability to hold water) are also prone to both shrinkage and expansion.


Examples Of Cohesive Soils Include:


  • Silt
  • Clay
  • Peat
  • Most loam


Non-Cohesive Soils

Unlike cohesive soils, purely non-cohesive soils do not clump together in any way . Their grains, in other words, remain separate from one another. Another way of looking at it is as a ‘free-running’ kind of soil. These soils can be prone to the process of liquefaction. The structural strength is dependent on the moisture content – think building sand-castles on the beach!


Examples Of Non-Cohesive (Or Granular) Soils Include:


  • Sand
  • Gravel
  • Some sandy loam


Why Does It Matter?

It matters because different soil types require different geotechnical services and engineering solutions. Looking at cable percussion drilling, for instance, the type required depends on the soil’s characteristics. In cohesive soils, for example, apparatus known as a ‘cutter’ should be used. In granular, non-cohesive soils, on the other hand, a piece of equipment known as a ‘bailer’ is most often used. The type of soil can also cause certain drilling problems. When drilling in cohesive clays, for instance, there’s the risk of the soil binding or ‘sticking’ to the drilling stem; essentially clogging it up. That’s why initial research is so vital to firms such as ours in determining what we’re dealing with, ground-wise.


What Services Do We Offer?

Whatever the ground you’re looking to have worked, the team here at Borehole Solutions Ltd can help! We’re proud to offer the following services:

  • Rotary Drilling
  • GSHP Installation
  • And More!


Contact Us

Next time you see your kids mucking about in the garden, ask them whether the soil is cohesive or non-cohesive. They’ll look at you and probably say “what are you talking about and what’s for tea? Can we get takeaway?” but at least you know a bit more about your garden and the ground beneath our feet, now! So, if you’d like to find out more about our site investigation services, then get in touch! Contact Borehole Solutions Ltd today on 01733 200 501 or by emailing us at info@boreholesolutions.com. Why not head over to our Instagram and see what other projects we get up to.