The use of sand in construction is fundamental, serving as a key ingredient in concrete, mortar, and various other building materials. However, not all sand is created equal, and the suitability of different types of sand varies depending on their physical and chemical properties. Among the various types of sand, desert sand has been a topic of debate. Can it be used in construction? The answer is both yes and no. In this article, we’ll explore the reasons why desert sand is generally not suitable for construction, and under what circumstances it might be used.
Why Desert Sand is Generally Not Used in Construction
1. Grain Size and Shape
One of the primary reasons desert sand is not typically used in construction is due to its grain size and shape. Desert sand grains are finer and smoother compared to other types of sand, such as river sand or beach sand. This smoothness means that the surface chemistry of desert sand cannot offer a sufficient number of multi-directional chemical linkages necessary for strong concrete.
In construction, sand is used to create a solid matrix within concrete. The angular and rough surface of river sand grains allows them to interlock well, providing the concrete with strength and stability. On the other hand, the round and smooth grains of desert sand do not interlock as effectively, leading to weaker concrete. If the grain size is too small, the slurry may slip, resulting in concrete with poor structural integrity.
2. Open Structure and Poor Interlocking
Desert sand possesses an open structure, meaning that there is little interlock between sand grains. While this might not seem like a major issue at first, it becomes a significant problem when the sand is used in construction. The lack of interlocking reduces the bearing strength of the concrete, especially when the sand becomes wet.
When the sand becomes wet, these bridges soften and can collapse under load, leading to a significant reduction in the overall strength of the concrete. This is particularly problematic in regions with fluctuating moisture levels, where the concrete might be exposed to cycles of wetting and drying.
3. High Salt Content
Another critical issue with desert sand is its high salt content. Desert sand often contains large amounts of salt, which can be detrimental to concrete. When used in concrete, the salt can lead to the corrosion of steel reinforcement bars, severely compromising the structural integrity of the building.
Salt can attracts moisture from the environment. This can lead to the formation of salt crystals within the concrete, causing it to crack and deteriorate over time. Additionally, the presence of salt in concrete can lead to efflorescence, where a white, powdery substance forms on the surface of the concrete as the salt migrates to the surface. This not only affects the appearance of the concrete but also indicates underlying structural issues.
When Desert Sand Can Be Used in Construction
Despite the challenges associated with using desert sand in construction, there are circumstances under which it might be feasible to use it.
1. Mixing with Other Materials
One potential solution to the issues associated with desert sand is to mix it with other types of sand that have more favorable properties. For example, mixing desert sand with river sand or crushed stone can help improve the overall grain size distribution, leading to better interlocking and improved strength in the concrete.
In some cases, desert sand can be used as a partial replacement for traditional sand in concrete, provided that it meets certain standards and specifications. Testing for grading, fineness, absorption, and deleterious substances is essential before using desert sand in construction to ensure that it will not negatively impact the quality of the concrete.
2. Specialized Applications
In areas where there is an abundance of desert sand and a scarcity of other types of sand, it may be necessary to use desert sand in construction. In such cases, the concrete produced may have lower strength, but for certain applications, this might not be a significant concern.
For example, in non-structural applications such as landscaping, desert sand might be used without significant issues. Additionally, researchers in China and other countries have been exploring the use of desert sand in construction, and some have found ways to improve its suitability for use in concrete.
3. Washing and Treating the Sand
If desert sand is to be used in construction, it is crucial to wash it thoroughly to remove dust, salt, and other impurities. Washing the sand can help reduce the salt content, making it less likely to cause corrosion in concrete. It is also important to check the chloride and sulfate contents, especially if the desert is near the sea, as these compounds can further compromise the integrity of the concrete.
In some cases, chemical treatments might be used to improve the properties of desert sand, making it more suitable for use in construction. These treatments can help enhance the bonding ability of the sand, reduce the likelihood of corrosion, and improve the overall strength of the concrete.
4. Innovative Research and Future Potential
As the demand for construction materials continues to grow, researchers are exploring innovative ways to use desert sand in construction. Some researchers have developed techniques to modify the properties of desert sand, making it more suitable for use in concrete.
For example, researchers in China have been experimenting with adding supplementary cementitious materials (SCMs) to desert sand to improve its bonding properties. These materials, such as fly ash, silica fume, and slag, can help fill the voids between sand grains, leading to improved interlocking and greater strength in the concrete.
Additionally, some studies have explored the use of polymers and other additives to modify the surface properties of desert sand, enhancing its ability to bond with cement. While these techniques are still in the experimental stage, they hold promise for the future use of desert sand in construction.
