Sandbag construction
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The Sandsackbau is a cost effective method of construction is used in the most locally available soil or rock as filler. The structures built with it are both stable and quick to construct.
The construction of building structures from sandbags has its origins in military bunker construction techniques and was further developed using techniques from, among other things, flood dike construction. The construction technology only requires simple, mostly locally available and very inexpensive building materials.
Filled sandbags have an inner stability. Either moist subsoil is used, which contains enough clay to become cohesive when tamped , or a water-resistant, angular gravel or crushed volcanic rock. Walls are gradually built up by laying the bags in layers and with an offset similar to classic masonry . The walls can be curved or straight, the roof can also be covered with sandbag vaults or conventional roofs. Curved walls offer good lateral stability, so the round rooms and / or vaulted ceilings that are often found are similar to an igloo .
Buildings with longer straight walls require crossing walls or bracing buttresses for stabilization. There are international standards for the size and spacing of retaining walls for earthen buildings, e.g. B. New Zealand earthquake safety standards for earthworks. Static shear tests show that sandbags filled with clay with specific soil strengths and reinforcements can achieve strengths similar to the New Zealand standards for reinforced clay bricks .
In order to improve the friction between the bags and the wall, barbed wire is usually placed between the layers. Sometimes twine is also wrapped around the bags to create a stronger bond between each layer, to hold structures under construction together, or to keep the layers well placed on the barbed tines. Corners and opening edges are reinforced in a similar way.
The structure is usually plastered with plaster of paris, either with cement plaster on a strong mesh layer or with a clay or lime plaster, this is done in addition to optical reasons, also to protect against UV damage to the fabric of the sandbags and to protect against moisture penetration.
Sandbag construction is one of the most versatile natural construction methods and can be used for benches, freestanding walls, emergency shelters, temporary or permanent shelters, or barns and commercial buildings. It is often chosen for many small to medium-sized institutional structures in developing countries or disaster areas. Underground structures such as dwellings, cisterns , spring boxes, root cellars and retaining walls can be filled with z. B. be built by cement stabilized soil filling or with additional reinforcement and water-resistant gravel or sand fill.
