Prospects of using metallized pellets as aggregates for heavy concretes

Abstract

Purpose. Analyzing possibilities of using various types metallized pellets as a large aggregate for the heavy concrete production for radiation protection particularly. The methods. The existing agglomeration technologies are analyzed. They are following: briquetting, pelletizing and high-temperature processes. The pellets production technology (the most rational non-firing) allows to obtain a fractionated spherical material from finely dispersed materials containing iron (about 60 - 68%). Replacing part of the coarse aggregate using metallized pellets will increase the strength and density of concrete, which is proportional to its ability to absorb γ-radiation. Samples are concrete cubes (size of 10 × 10 × 10 cm), made according to ДСТУБВ.2.7-114-2002 and exposured during 28 days to acquire a grade strength. Findings. For the experiment 2 batches of concrete mixture were made. For preparing the batch, the required amount of M400 cement, sand and coarse aggregate for testing was weighed using an electronic balance.Crushed stone was used as coarse aggregate for the first batch, and for the second batch crushed stone and pellets were used. The mixture’s reserve ratio was 20%, the fraction of crushed stone was 20-40 mm, pellets of “Poltava Mining and Processing Plant (Ferrexpo Poltava Mining)” with an average diameter of 15 mm were also used. The originality. It is proposed to replace part of the coarse aggregate using metallized pellets, which gave the so-called "uniform heterogeneity" of the concrete mixture, increased the density, which is proportional to the concrete ability to absorb γ-radiation, and improved the strength properties of concrete samples as a result. Practical significance. It was found that replacing a part of the coarse aggregate using pellets increases the strength of hardened concrete by 36%, and a sufficiently high pellets’ Ferum content (65%) allows us to consider the prospect of their use for radiation protection concrete the construction of structural elements of strategic facilities. Using pellets obtained from waste (sludge and slag) will expand not only the range of building materials, but also the areas of their use, and reduce the burden on the environment.