In the ever-evolving construction industry, the quest for sustainable and efficient materials is a constant driving force. A recent study, conducted by Abba Fatiha of the Geomaterials Laboratory at the University of Hassiba Benbouali of Chlef (Algeria), has shed new light on enhancing the performance of recycled aggregate concrete (RAC) using supplementary cementitious materials (SCM). This research, published in the journal ‘Cleaner Materials’, offers promising insights that could revolutionize the way we approach concrete production, particularly in energy-intensive sectors.
The study focuses on the substitution of natural coarse aggregates (NCA) with recycled coarse aggregates (RCA), a practice aimed at reducing waste and preserving natural resources. However, RCA is often of poor quality due to old mortar attached to its surface, leading to issues like low density, high absorption, and a poor interfacial transition zone (ITZ). These factors result in a lower quality concrete, which can be a significant drawback in high-strength applications, such as those found in the energy sector.
Fatiha and her team set out to mitigate these issues by incorporating SCMs into RCA-based concrete. In their experiments, they replaced ordinary cement with various SCMs, including natural pozzolan (NP), limestone powder (LP), ground granulated blast furnace slag (GGBFS), and fumed silica (SF). The results were striking.
“The use of SCMs not only improved the mechanical strength of the concrete but also enhanced its durability and microstructure,” Fatiha explained. “In the long term, RAC concrete with SCMs showed a significant reduction in shrinkage strain, ranging from 20% to 44%.”
One of the most compelling findings was the impact of different SCMs on the compressive strength of RAC. While RAC concrete typically exhibits a 12% lower strength than ordinary aggregate concrete (OAC), the use of limestone powder reduced this decrease to just 3%. Even more impressively, GGBFS and SF resulted in 9% and 28% higher strengths, respectively.
The implications of these findings are far-reaching. For the energy sector, where concrete is often used in large-scale projects like power plants and wind farms, the enhanced performance of RAC could lead to more durable and cost-effective structures. The ability to use recycled aggregates without compromising on strength or durability is a game-changer, particularly in regions where natural aggregates are scarce or environmentally sensitive.
Moreover, the reduced shrinkage strain observed in RAC with SCMs could have significant benefits for long-term structural integrity. In energy infrastructure, where structures are often exposed to extreme conditions, minimizing shrinkage is crucial for maintaining structural stability and longevity.
This research opens up new avenues for the construction industry, particularly in the energy sector, where sustainability and efficiency are paramount. By leveraging SCMs, engineers and builders can create more resilient and environmentally friendly structures, paving the way for a more sustainable future. As the demand for green construction solutions continues to grow, the insights from Fatiha’s study, published in ‘Cleaner Materials’, could shape future developments in the field, driving innovation and sustainability in the construction industry.