Author(s): Turco, Chiara ; Teixeira, Marta Sofia Aguiar Carvalho Oliveira ; Teixeira, Elisabete Rodrigues ; Mateus, Ricardo
Date: 2025
Persistent ID: https://hdl.handle.net/1822/97099
Origin: RepositóriUM - Universidade do Minho
Subject(s): Earthen constructions; Compressed earth blocks; Agro-industrial by-products; Mechanical properties; Durability; Non-destructive testing
The construction industry urgently needs engineering solutions that reduce embodied carbon and promote circular material flows. Compressed earth blocks (CEBs) represent a promising low-carbon alternative, but their large-scale use is challenged by issues of mechanical strength and durability, particularly when natural materials are incorporated to improve thermal performance. Due to the inherent variability of natural products, their interactions within mixtures are still poorly understood, and quality control of the resulting materials is lacking. This study provides a comprehensive investigation of CEBs incorporating two agro-industrial by-products, wheat straw (WS) and cork granules (CGs), sourced locally from Portuguese production chains. The experimental program evaluates mechanical properties (compressive strength, tangent stiffness, flexural strength, fracture energy) and water absorption behaviour (capillary absorption, total immersion), and integrates non-destructive testing (NDT) techniques, including ultrasonic pulse velocity (UPV) and electrical resistivity, to outline practical guidelines for optimising additive content while ensuring mechanical performance and durability. Results indicate that the lowest 5% volumetric addition of WS yields the best balance between enhanced mechanical performance and acceptable water resistance. In contrast, CG additions must be limited to 3–5% by volume to avoid significant losses in strength and water resistance. The study demonstrates the diagnostic and predictive capacity of NDTs for the materials tested, with UPV correlating well with strength and stiffness, and electrical resistivity effectively reflecting capillarity. NDTs offer scalable, field-applicable tools for quality control, supporting a broader and more confident use of bio-based materials in modern construction.
