Ground Improvement Using Recycled Concrete Columns: A Case Study of Wind Turbine Foundation

There is a growing global trend toward reducing the consumption of natural resources and newly produced construction materials by replacing them with secondary raw materials. Concrete derived from construction and demolition waste can be recycled multiple times and is considered environmentally sustainable. This study evaluates the feasibility of reinforcing weak subsoil using crushed recycled concrete. Concrete obtained from the demolition of residential buildings was crushed under laboratory conditions to produce material with grain sizes corresponding to sands, and mixtures were subsequently prepared containing up to 30% fine fraction. The case study focuses on circular wind turbine foundations supported by symmetrically arranged columns made of four different materials, located beneath the foundation slab. The analyzed subsoil is characterized by strong stratification, low bearing capacity, and high compressibility. The calculation results indicate that the bearing capacity conditions for all foundations were met within similar ranges of the safety factor for the given loads, both for low- and high-power turbines. However, foundation deformations increased with turbine size and bending moments, and were nearly twice as large for recycled aggregates compared to recycled concrete. Numerical simulations demonstrate that recycled aggregate without fine fraction, as well as with fine fraction, and recycled concrete can provide load-bearing performance comparable to conventional concrete under low loading conditions, while offering significant environmental benefits.