Water absorption of ‘franka’ stone dust and its effects on mix design

Abstract

Most Maltese construction up until recently depended mainly on Globigerina limestone (‘Franka’) as a building material. However, modern environmental considerations and resource limitations have encouraged the reuse of quarry waste in reconstituted stone production. This study investigates the water absorption characteristics of ‘Franka’ stone powder with particle sizes below 2 mm and evaluates how these properties influence mix design, particularly in achieving workability and structural performance without the need for compaction load. A detailed experimental programme was conducted, including wet and dry sieve analyses, pycnometer absorption tests across multiple particle sizes, Vicat consistency and setting time tests, flow table assessments, and compressive strength tests on vibrated and hand-compacted cylinders. The mixes were designed using a fixed 12.5% cement content and a 5% admixture, with variable water content adjusted based on absorption findings. The results indicate that high absorption rates of the fine Globigerina aggregate significantly impact compressive strength because of high water demand. Optimal water content, when paired with vibration, allowed the production of castable and structurally viable blocks without increasing cement dosage. Comparisons with previous local studies show comparable compressive strengths, validating the importance of water in the mix and how it effects the cured mix.