Analysis of Strength Gain by Precast Concrete Elements in Winter Conditions

Despite the significant dominance of monolithic construction over prefabricated construction, the latter method remains relevant for infrastructure, industrial and public construction in Ukraine. Given the challenges of today, military operations, energy difficulties, there is a growing need to accelerate the pace of construction of buildings and structures, including in winter conditions. This can be achieved through the use of precast concrete structures, the assembly of which requires minimal energy and logistics. Given the need to speed up the precast manufacturing cycle at construction plants as much as possible, finished products (precast concrete elements) are delivered to construction sites within 10-15 days, when they have reached 50-70% of their design strength. Further aging and strength gain is predicted under conditions that differ from the normative ones, which can reduce the rate of strength gain. As part of the study, the strength of precast concrete elements was measured, which were installed and aged in winter conditions. The measurement was performed by a non-destructive mechanical method (spring rebound method) with an electronic sclerometer, on more than 50 reinforced concrete structures (slabs). The strength of the elements was analysed by measuring the surface strength at 10 points (for each element), with the exclusion of obvious erroneous values, calculating the average strength, determining the coefficient of variation and the root mean square error. It was found that the strength of some elements decreased as a result of exposure to negative temperatures until the design strength was reached. A list of measures has been compiled to avoid a decrease in strength and restore the process of gaining design strength.