Department of Architecture and Civil Engineering

A low-cost field test kit for earth construction applications

At a glance

Funding body: Institution of Civil Engineers (ICE) Research and Development fund, University of Bath
Principal investigator: Andrew Heath
Researcher: Natalie Price
Dates: 2011-2012

Abstract

This project consisted in the development of a low-cost, portable field laboratory/test kit to determine the material properties relevant to earth construction, thereby allowing reliable quality control.

Compressed earth blocks (CEBs) and other forms of earth construction are extensively used in developing and disaster areas as a replacement for fired bricks and concrete blocks in small building construction.

There are a number of NGOs and other development organisations involved with this form of construction around the world.

Unfortunately the quality control on these projects is often limited to visual inspection of materials to determine their suitability for use, without knowledge of their engineering properties. This can lead to inefficient or unsafe use of materials.

Research over the years has confirmed the required soil properties for both stabilised and unstabilised earth construction, but the tests normally have to be undertaken in a soils laboratory not available in many developing and disaster areas.

Therefore the project aimed to develop a low-cost, portable field laboratory/test kit to allow for reliable quality control of earth construction.

The following requirements were determined for a field test kit:

  • Acceptable accuracy for earth construction
  • Lightweight for transport to relatively remote sites
  • Robust and easily repairable
  • Use without access to a reliable power supply
  • Low-cost and sourced from non-specialist suppliers
  • Equipment for soil identification and finished product quality control included.

The test methods are based on existing laboratory methods to aid acceptance by funders and to ensure compatibility with research. It is therefore important that operators are familiar with these tests and training is required for operators who are unfamiliar with the standard tests.

The result is a field test kit which costs £380 (plus three days workshop time) to assemble, with a total mass of 23.2kg (10.6kg for soil identification only).

This is considerably lighter than the soil which would have to be transported to a central laboratory for testing.