Increase of aggregative and sedimentation stability of slag suspensions by ultrasound

Increase of aggregative and sedimentation stability of slag suspensions by ultrasound

Ivan Petrov^{1 [0000-0002-8898-2883]}

¹Moscow State University of Civil Engineering, Yaroslavskoye shosse, 26, 129337, Moscow, Russia, IvanPetrov@mail.ru

Abstract.The paper discusses the relevance of the use of metallurgical wastes crushed to a fine state in the production of building materials. Domain granulated slag (DGS) was used as a research object. It was used to obtain a finely ground additive by grinding in a laboratory jet mill. Grinding of slag was carried out with the restriction of the upper limits of grinding to a particle size of 1 micron. The predominant particle size of the slag after grinding was 0.5 - 1 micron. A method for introducing fine ground slag (FGS) into the cement composition in the form of a slag suspension instead of mixing water has been developed. To establish the uniform distribution of FGS particles in the cement matrix, the behavior of slag particles in an aqueous dispersion medium was previously studied. It is established that FGS particles in suspension form micelles of two types with negative (micelle 1) and positive (micelle 2) surface charges. The presence of a double electric layer in the slag particles causes the aggregative and sedimentation stability of the FGS suspension due to the electrostatic factor of the aggregative stability. To increase the aggregative and sedimentation stability of the slag suspension, it was subjected to ultrasonic treatment (UST). The optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is 44 kHz; temperature of dispersion - 25±2°C; dispersion time - 15 min. It has been established that the application of UST to slag suspensions with the observance of optimal dispersion parameters can increase the aggregative and sedimentation stability of the FGS suspension by 2–3 times as compared with mechanical mixing, accelerate the micelle formation process, and enhance the electrostatic factor of aggregative stability. The strength of samples with FGS suspensions prepared using UST under recommended dispersion conditions increased by 19 – 39% for the first day; for 28 days of hardening - by 19 - 36%. It is noted that when deviating from the optimal dispersion parameters, the acceleration of coagulation of slag particles, the formation of aggregates, the reduction of aggregative and sedimentation stability of FGS suspensions, and the deterioration of the strength characteristics of cement stone are observed.

Keywords: development, stability of interaction, proportionality

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