The article presents an analysis of objects with concrete-filled steel tube columns. Also the article describes methods for solving the concomitant disadvantages and describes ways to increase the effectiveness of this solution. Prospects for studies of increasing the adhesive component of the mutual work of the concrete core and steel shell are presented. The analysis allows you to give recommendations on the following issues: improving the technological level of concrete-filled steel tube columns, the convenience of joining the column with the frame.
Keywords: concrete-filled steel tube columns, combined steel and reinforced concrete structures, tubular section, fixed formwork, steel cage, concrete core, adhesion of materials, side compression effect, frame building, construction in the low-temperature conditio
The composition, basic properties and application scope of the two main types of expanding binders historically most widespread in Russia such as gypsum-alumina expansive cement and expansive cement Type M are given. The expansion kinetics of the binders ranging from gypsum-alumina expansive cement to expansive cement Type M is observed. The role of lime as a supplement and as a hydration product of the Portland cement in the expansion process is shown: as a supplement in small values (2-4%) to gypsum-alumina expansive cement with higher gypsum concentration stabilizes the hardening and expansion process, in higher values boosts the expansion process to self-destruction. Optimization criteria of the expansion kinetics aimed at obtaining project expansion in 10 days of hardening without any additional chemical additives are proposed.
Keywords: gypsum-alumina expansive cement, expansive cement type M, expansion kinetics, lime