Improvement of shrinkage and expansive soil properties using nano-copper

Nanoparticles are now becoming a common material and currently produced in bulk worldwide to warrant possible use in construction and for improvement of infrastructures. This paper presents an experimental study on the use of nano-copper to enhance the shrinkage and expansive behaviour of soils. This behaviour is the result of loss of soil water content which develops matric suction in soil that increases the shrinkage strain in the soil and normally results in cracks. The term desiccation is also normally used to describe this phenomenon which will cause high hydraulic conductivity in soils leading to failure of slopes, retaining walls and landfills. In the past, sand, lime, and fibres were used to arrest shrinkage. However, at the same time hydraulic conductivity increases significantly. Tests were conducted on four types of soils mixed with nano-copper of different amounts. The soil specimens were compacted under the condition of maximum dry unit weight and optimum water content using the standard compaction test. It was found that there was a significant improvement by nano-copper in terms of expansive and shrinkage strain. This is possibly because the particle density of nano-copper is high which increases the specific gravity of the soil–nanomaterial mixture leading to increase in the maximum dry density of the mixture. The results also showed that nano-copper decreases the development of desiccation cracks on the surface of compacted samples without increasing the hydraulic conductivity.