Instytut Podstawowych Problemów Techniki

Abstract:
The paper presents a laboratory investigation into the influence of power ultrasound treatment on the reactivity of diatomite in cement-based materials. Diatomite powder was used as a partial replacement of Portland cement in paste and mortar produced using power ultrasound with acoustic energy up to 61 J. The effects of sonication were evaluated in terms of diatomite pozzolanic reactivity, cement hydration kinetics, mechanical properties, and microstructural features of hardened cement paste and mortar. The sonofragmentation of diatomite particles increased with increasing sonication exposure time. The modified Chappelle test revealed that the sonication of diatomite increased Ca(OH)2 consumption by up to 1984 mg/g. As a result of sonication for 10 min. the best-performing diatomite + cement paste exhibited a considerably increased early compressive and flexural strength, by 180 % and 34 %, respectively, also an increased specific surface area (by 69 %), and reduced substitute setting times (by about 35–40 %). The strength activity index of diatomite increased from 57-65 % to 84–90 % due to sonication, showing its efficiency in improving both the early and late strength of diatomite + cement mortar. Such effectiveness is linked to the sonofragmentation and diatomite particle breakage induced by power ultrasound. Results of the study contribute to the development of sonication-assisted manufacturing of low-carbon cement-based materials

Keywords:
Diatomite, Early strength development, Power ultrasound treatment, Portland cement, Pozzolanic activity, Sonofragmentation, Ultrasound mediated particle breakage