Durability and stability performance of compressed earth blocks (CEB) made with sediment and FA

Purpose This study aims to evaluate the mechanical behavior and durability of sediment-based compressed earth blocks (CEB), linking the evaluation to the ability of CEB to resist weathering and physical attack while retaining the desired mechanical properties through compressive strength tests, behavior under drying-wetting cycles and the evolution of drying shrinkage. Design/methodology/approach The stabilization was achieved by partial substitution of sediments for fly ash (FA) with six different percentages 0, 10, 20, 30, 40 and 50% of the sediment by volume. The curing temperatures of all the mixtures were at 50°C for 7 days in an autogenous condition. All the CEB samples were characterized in terms of mechanical and durability properties. Findings The results show that the dosage of sediment-FA has a significant impact on CEB properties, as the FA dosage increased, the porosity decreased and the compressive strength increased. When the FA dosage increased from 0 to 50%, the CEB drying shrinkage decreased by 67%. The CEB containing at least 20% FA are well adapted to load-bearing wall applications in buildings in terms of mechanical performance, thermos-hydric stability, volumetric stability and environmental acceptability. Originality/value Dredged sediments without binders generally have poor mechanical properties. In order to improve the geotechnical characteristics and mechanical performance of these sediments, the addition of a geopolymeric binder “stabilizer” based on sodium hydroxide (NaOH)-activated FA is an effective solution. This geopolymeric binder improves cohesion between sediment grains by means of a chemical effect, involving the hydration of FA and a physical effect, reducing voids to obtain lower compressibility and better mechanical strength as well as durability.