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

AbstractThe 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.Keywords: Volcanic tuffactivationcementwet millingcalcination Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThe authors thankfully acknowledge the financial assistance from the Deanship of Scientific Research at Jordan University of Science and Technology under grant number 2021/383.