“Egyptian feldspar” enhances the strength of concrete and promises a green future sciences

A recent scientific study revealed that the use of feldspar, which is widely available in the Egyptian desert, can bring about a qualitative shift in the performance of alkali-activated concrete, which is one of the most important low-emission alternatives to traditional concrete, by improving its durability and reducing its water permeability.

The study, prepared by a research team from the National Center for Housing and Building Research, and recently published in the Journal of Engineering and Applied Science, sought to exploit local resources to enhance the efficiency of concrete, which is one of the most consumed materials in the world and alone contributes about 8% of global carbon emissions.

Feldspar is a group of rock minerals, consisting mainly of aluminum silicates that contain potassium, sodium, or calcium. It is considered one of the most widespread minerals in the Earth’s crust, as it constitutes about 60% of its composition. It is a major component in igneous rocks (such as granite and basalt), as well as in some metamorphic and sedimentary rocks.

Partial replacement

According to the research, different proportions of feldspar were tested as a partial replacement for “slag” in alkali-activated concrete, a material commonly used to improve its mechanical properties. Replacement rates ranged between 10 and 50%, with the effect measured on flexural strength, corrosion resistance, water permeability, and drought shrinkage.

The results showed that adding only 10% of feldspar achieved the best equilibrium performance of concrete, as the bending strength increased by about 24.5% during the first week of hardening compared to traditional concrete. The surface corrosion rate also decreased by more than 10%, and water permeability decreased by 15%, which means that the concrete has become more resistant to water leakage and harsh environmental factors.

The research team explained that feldspar in this ratio acts as a “fine filler” that fills the voids in the concrete structure and makes it more cohesive. This directly reflects on its durability and longevity, while also helping to reduce shrinkage resulting from drought, which usually causes cracks in structures over time.

Special type concrete

However, the study warned that increasing the percentage of feldspar to more than 20% leads to adverse results, as the properties of concrete begin to gradually decline, its resistance to bending decreases, and its susceptibility to water leakage increases, which is attributed to the decrease in the amount of effective binder in the cement mixture.

The researchers believe that this approach not only provides an environmental solution that reduces the emissions of the concrete industry, but also carries economic benefits, as it reduces dependence on imported materials by adopting local raw materials that are widely available in Egypt, such as feldspar, which opens the door to the development of more sustainable and less expensive building materials.

Alkali-activated concrete is one of the most promising alternatives in the world of green construction, due to its ability to reduce emissions by up to 80% compared to traditional concrete, which makes improving its properties an essential step in the construction sector’s endeavors towards sustainability. The study confirms that a simple addition of a locally available metal could make a big difference in the future of building materials, at a time when global pressures are increasing to move to lower carbon production patterns that are more compatible with climate goals.