Evaluation of the effect of enrichment of slag aggregate for pavement subbase by grains density on its physical and mechanical characteristics

Laboratory evaluation of a complex treatment technology for reducing water absorption of the pavement subbase aggregate from the blast-furnace slag

“…There is approximately 500 kg of blast-furnace slag per ton of produced cast iron. This is approximately 500 million tons of BFS in the world for each year which requires recycling [1].…”

“…A large number of scientific studies have been devoted to the problems of recycling industrial wastes of metallurgical production, including BFS [1][2][3][4][5][6]. A special place among the areas of research in the field of recycling blast-furnace and steel-smelting slags is occupied by the possibility of use these materials in construction and civil engineering [7][8][9][10][11][12][13][14][15][16][17][18][19][20], including production of cement [7][8][9], mortars, slag-alkaline binders [10,11], concrete [12][13][14], fine and coarse aggregates [15][16][17], mineral wool [18], ceramic paving stones [19], geopolymers [20].…”

“…Due to the limited demand for BFS in regions with metallurgical production, despite the recycling of most of this material by the methods described above, a significant part of slag is still sent to dumps that occupy huge areas and require disposal. For example, according to data for 2023, more than 30 million tons of air-cooled blast furnace slag (ACBFS) have been accumulated in the dumps of Qarmet JSC (figure 1) [1]. The area occupied by this blast furnace slag dump alone is more than 700 thousand square meters.…”

“…Most of the current research [21][22][23][24][25][26][27][28][29] in the field of ACBFS recycling is devoted to the issue of its use as coarse aggregate in the construction of structural pavement layers instead of the natural stone aggregate, including clay subgrade strengthening [1,21]. For example, the authors of articles [21][22][23][24][25][26][27][28][29] considered the environmental friendliness of BFS use in road construction is assessed, the use of this material both for the pavement base layer and as aggregate of asphalt concrete mixture, as well as the possibility of complex use of a mixture containing slag with granite aggregate [27].…”

“…Literature review of BFS recycing methods shows, that the main problem preventing the full replacement of natural stone aggregate with slag aggregate (SA) based on ACBFS in base pavement layers is different porosity of this material grains. Studies [1] have shown that ACBFS contains both high-porosity and low-porosity grains. It was also experimentally proved in [1] that high-porosity grains have significantly higher water absorption, low bulk density, low frost resistance and a higher aggregate crushing value (ACV) compared with low-porosity grains.…”