Pre-treatment of volcanic tuff for use in high volume cement replacement: Fid-Bau Portal

Pre-treatment of volcanic tuff for use in high volume cement replacement

Ababneh, Ayman / Matalkah, Faris / Aqel, Ruba

The poor reactivity is the major limitation of the use of high replacement levels of volcanic tuff in concrete mixtures. The primary focus of this study is to develop a systematic methodology to identify an effective activation technique that enhances the reactivity of volcanic tuff for its application in large-volume concrete applications. Realizing the application of low-reactivity volcanic tuffin cement mortars, various activation methods such as dry-milling, wet-milling, and calcination have been used to improve the reactivity of raw volcanic tuff powder. Practical size distribution, specific surface area, XRD, TG/DTA, SEM, and Chappelle test were employed to assess the chemical and physical changes in the raw volcanic tuff particles after performing different activation methods. Mortars with 50% replacement are characterized by measuring compressive strength, strength activity index (SAI), mass loss, and residual strength after exposure to elevated temperatures, XRD, TGA/DTA, and SEM of all mortar mixes were investigated. The results showed that the compressive strength of specimens with 50% replacement of volcanic tuff which was activated by dry-milling, wet-milling, and calcination after curing for seven days, could reach 116%, 98%, and 77% of that of control specimens, respectively. Mixtures containing dry-milling volcanic tuff demonstrated optimal results in both compressive strength values and strength activity index. The results revealed that the activated volcanic tuff improved the mechanical properties of high-volume cement-volcanic tuff blendes due to effective physical filling led to denser microstructure and improving the pozzolanic reaction led to the production of higher amounts of Calcium-Silicate-Hydrate.