The Effect of Cellulose Fibers Recovered from Primary Sludge on Concrete Performance

The construction industry faces urgent pressure to adopt sustainable, low-carbon materials. Fiber reinforced concrete appears as a more sustainable alternative to conventional concrete due to its improved mechanical properties and durability. Commonly tested synthetic fibers do not provide holistic economic and environmental benefits. Wastewater treatment plants (WWTP) are emerging as resource recovery hubs for biopolymers like cellulose, offering an eco-friendly alternative to synthetic fibers. However, the application of sewage-derived cellulose fibers in cementitious composites remains under-explored. This study evaluates the integration of cellulose fibers, extracted from primary sludge of a WWTP as an alternative to synthetic fibers in concrete applications. We incorporated recovered cellulose fibers at a 0.2% w/w into concrete (0.5% v/v) and evaluated the fresh and hardened properties of this fiber reinforced concrete. While fiber addition reduced workability due to high water absorption, it significantly improved mechanical performance. Compressive strength increased by 5% at 7 days and 6% at 28 days. These improvements are attributed to internal curing effects and enhanced fiber-matrix bonding. This research demonstrated a viable pathway for upcycling sewage-derived cellulose into sustainable construction materials within a circular economy framework.