Problems and prospects of self-compacting concrete mixes for high-strength concrete

Abstract

The prospects and problems of multilevel optimization of the dispersed composition of self-compacting concrete are considered with the aim of significantly increasing its construction and technical properties, with a minimum content of binder. Theoretical and practical principles have been developed for designing the rational composition of concrete with an increased concentration of solid phase per unit volume and operational properties with a complex organomineral additive based on the optimal ratio of finely dispersed mineral and chemical components that optimize its dispersed composition and structure. It is shown that it is advisable to use particles of the clinker phase of several geometric sizes. To study the properties and structure of concrete, we used two fractions of fine aggregate, granite-gab rubble FR. 5-10 mm, Portland cement of class CEM I 42.5N, finely dispersed granulated blast furnace slag, metakaolin, silica fume, highly dispersed cement fraction, Glenium 430 superplasticizer and highly valent hardening accelerator. Research methods: the shape and size of the dispersed particles of the components were determined by a laser analyzer, the mobility of the concrete mix in accordance with GOST 10181-2014, the compressive strength of concrete in accordance with GOST 10180-2012. The structure of the cement stone was studied using scanning electron microscopy, thermographic and X-ray phase analysis methods. The strength of concrete with an optimized dispersed composition, superplasticizer and a highly valent hardening accelerator prepared using self-compacting concrete mixtures, aged 1 day after hardening under normal conditions (NU) was 58; 67; 77, and in 28 days - 150; 186; 219 MPa with cement consumption of 650, 710, 770 kg/m3, respectively. Multilevel dispersion-granulometric analysis in combination with chemical modification of the composition of self-compacting concrete mixtures ensures the synthesis of high-strength concrete with a minimum consumption of Portland cement and high physical and mechanical properties. It is advisable to use several structural levels of particles of the clinker component.