Rammed earth

Construction process of rammed earth.

Drawing on knowledge that dates back over 10 centuries, and was used to build the Great Wall of China only five short centuries back, rammed earth is natural, sustainable, 100% green and extremely cost effective.  As the world buzz is green focused, Vexiflex, and other local builders, are starting to explore the applications of this building methodology that uses sand, gravel, lime and chalk.

Earth is a natural, durable, healthy and strong building material and has around 300-psi compressive strength rating.  It doesn’t require the use of toxic treatment substances that some building materials require which minimizes its carbon footprint.  The process involves the erection of steel and wood frames that are placed parallel to each other.  The damp earth mix is poured down the middle to a depth of around 10-25cm and then compacted to about 50% of its original height. 

Traditionally, thousands of years ago, lime or animal blood was used as a stabaliser, today, cement or asphalt are commonly used as a contemporary alternative.  This diagram shows the basic concept of the pouring and compacting of the earth.

The wet mixture is poured in and compacted.  More mixture is poured
over it and the procedure continues until the wall reaches the desired height.

One of the biggest attractions that rammed earth offers to our clients is the unique and stylish finish of each wall.  No wall will ever look the same and they can be left in their naked finish with no paint or plastering needed.  Depending on the materials used, each wall has a distinctive pattern or grain and becomes a focal feature in itself.

On the left is a closeup of a rammed earth wall, the right shows a wall with a door frame.
<source>

As a green builder, we have been impressed by the low embodied energy (energy and resources required to manufacture) and the thermal mass that it offers.  In the hot Boland climate the walls absorb most of the heat during the day and release it during the cool evenings.  In areas where the daytime temperatures are lower, extra insulation may be added, making rammed earth an extremely attractive alternative to clay and stock bricks.

Due to the seasonal heavy rains that we experience, rammed earth walls may be stabilised with 10% cement to assist with strength and durability against consistent and excessive rain force.

Using natural and readily available resources from local soils, Vexiflex will be able to build houses that are truly eco-system friendly.  We will be growing our knowledge base and skills in rammed earth construction and encouraging our clients to consider this for their homes.  Contact us today for more information or rammed earth construction.