Оцінювання якості крупного заповнювача, отриманого з подрібнених бетонних залізничних шпал

Abstract

UA: У статті наведено результати оцінювання якості вторинних заповнювачів, отриманих із подрібнених залізобетонних шпал, за гранулометричним складом, лещадністю і стиранням. Проведено порівняння результатів визначення за стандартними методами і запропонованим методом обробки зображень. Установлено, що останній дає більш точні і швидкі результати. Уточнено середній розмір частинок щебеню переважальної фракції, ступінь окатаності, час стирання. Використання перероблених заповнювачів зменшить потребу будівельної галузі в природних ресурсах, знизить вартість виробництва бетонних конструкцій і скоротить площу земель, зайнятих будівельним сміттям.

EN: The increasing urgency of reusing debris from demolished concrete structures is a global issue, not just confined to Ukraine. Current strategies for resource reuse involve crushing concrete waste into recycled aggregate to replace natural aggregate, or into recycled powder to substitute for cement in mortar and concrete. Utilizing construction waste as secondary materials helps reduce the demand for natural resources, decrease carbon footprint, and clears areas of accumulated remains. The aim of the work is to evaluate the quality of aggregates obtained from crushed concrete of railway sleepers. To achieve the goal, the following tasks were set: to determine the particle sizes of aggregate fractions by the standard and accelerated methods; to determine the content of plate-shaped (flaky) and needle-shaped grains by the standard method and the accelerated method; to determine the abrasion time of crushed stone; to compare the obtained data with the standard requirements for concrete aggregates; to give recommendations on the application of the accelerated method for assessing the properties of coarse aggregate. The most representative fraction of coarse aggregate based on the results of sieving is the fraction with an average particle size of 30 mm, while a more accurate image processing method yields an average size of 22.6 mm. Such a discrepancy will lead to errors in calculating concrete compositions and excess cement consumption or obtaining concrete of lower strength. Based on the content of plate-shaped (flake) and needle-shaped grains, determined by the standard method over several hours of measurements, secondary crushed stone belongs to the cubic group of concrete aggregates. An assessment by the image processing method over several minutes yields a circularity of 0.78, which characterizes a greater degree of grain circularity after mechanical processing. The highest percentage of old cement-sand mortar removal occurs in the first 1-1.5 hours, which will form the basis for developing a technology for using aggregates from concrete residues. Subsequent studies will be aimed at establishing the quality of sand using the proposed methods for developing express methods for assessing the quality of coarse and fine aggregates, which will allow determining their properties directly at construction sites.