A retaining wall is an external wall constructed for the main purpose of containing a mass of earth on a slope. It is constructed to withstand the pressure from the earth that tends to slide downwards on a slope. Its design features and materials are picked to suit the load it is meant to withstand. There are different types of retaining walls based on the materials used and their design features. Among them include Cantilever retaining walls and mass retaining walls.
Read about typical retaining wall construction by clicking here.
The construction of retaining walls follows the construction and design principles similar to that of a typical retaining wall though it incorporated sustainability either in terms of the materials used or the construction approach.
Sustainability is a key consideration when designing or retrofitting walls because it can help reduce the environmental impact of a construction project. With climate change being one of the most pressing issues of our time, sustainable construction is at the forefront of current construction trends.
Players in the construction industry are challenged to come up with sustainable methods of construction both in terms of technique and material. Among them include the Use of biodegradable materials, recycling of none biodegradable materials, use of locally available construction materials rather than factory manufactured materials, and using resource-conserving methods of construction among others.
This article looks at the different kinds of retaining walls including wooden retaining walls, rammed earth retaining walls, reusable glass retaining walls, and gabions.
Wooden retaining wall; Wooden retaining walls are an environmentally-friendly and cost-effective way to build a wall. Unlike concrete, which requires large amounts of water and energy to produce, wooden retaining walls require only a small amount of wood and can be built quickly using simple construction methods.
The best kind of lumber for these walls is Douglas fir pressure treated with preservatives to discourage rot. These retaining walls are less likely to cause environmental damage because of they are biodegradable.
The downside of this type of retaining wall is that exposure to moisture causes wood rot reducing the longevity of the retaining wall. This is remedied by installing a layer of waterproof sheeting applied to the back side of the timber retaining wall to separate it from direct contact with fill.
There is also gravel packing behind the wall, particularly at the bottom where water accumulates during rainy conditions. This is done for better drainage and to reduce the negative impact of water on wood.
Rammed earth retaining wall; This type of retaining wall is designed by ramming a mixture of soil, gravel, sand, silt, and a small amount of clay into a compact block between formwork panels. The formwork can be made from wooden panels, metal, or plastic sheets. The ramming is done using a wooden pole to compress the mixture.
Modern technology replaces the wooden pole with a mechanical ram. Typical rammed earth retaining walls can be constructed largely from clay, sand, and a little cement which can be mixed in a ratio of 60%, 30%, and 10% respectively. The materials are mixed with a little water to make it workable.
Earthbag retaining wall: These types of retaining walls are constructed using bags filled with earth. The earth is sorted for any plant matter like grass and leaves then packed into polythene bags and sacks. The earth is rammed slightly to make it compact, then filled and the bag/sack sealed. The resultant bag is firm and rigid and used as a building block for the retaining wall. The bags are arranged in layers, one over the other.
They rely on their mass for their retaining wall properties. These walls are sustainable because of two reasons; They reuse polythene bags–which would have otherwise been a pollutant when disposed of in the environment–and they use an environmentally friendly material which is natural earth.
Reusable glass retaining wall; These are built using used glass bottles that are intact. The glass bottles are arranged horizontally in layers from down upwards. The glass bottles are bound using mortar. The hardness of the glass gives it sufficient strength to be used in the place of bricks.
This retaining wall is environmentally friendly because it makes use of glass bottles which are potential pollutants when disposed of in the environment. The bottles also do not require further processing processes like burning bricks which is hazardous to the environment.
The downside of this type of wall is the danger it poses when the brittle glass is damaged. Broken glass is very sharp and can easily cause injury, especially the bits and pieces that chip off and could fall along a path and cut a passerby.
This can be remedied by using a lot of mortar as a binding material to cover and plaster most of the class such that very little or none of the glass is exposed.
Gabions; These are retaining walls made up of stones and gravel, enclosed by a wire mesh. The mesh holds the stone and gravel together into a mass that constitutes the wall. This type of retaining wall is very simple to construct and is less expensive.
Moreover, since the stones are held together by a wire mesh, there’s no need for another binding agent like cement. they also have very good water drainage properties. This is because they are made of stones, arranged to be porous such that water can easily sip through. They are also easy to maintain.
The downside of this type of retaining wall is that it has a limited load-bearing capacity since its strength relies not only on the mass of the rocks but also on the strength of the wires.
In conclusion, sustainably-built retaining walls are an environmentally-friendly and cost-effective way to keep your property safe and secure. While sustainability is not always easy to achieve, it is definitely worth considering when planning a wall project. By using recycled materials and designing wall systems that are resilient to environmental changes, your wall project can be a valuable part of a sustainable community.