This paper presents the results of tests of selected physical and mechanical properties as well as the chemical composition of two types of natural aggregates: porphyry and diabase, as well as artificial aggregate based on steel slags. Based on the conducted tests, it was established that the physical and mechanical properties of the artificial aggregate exhibit slightly lower parameters as compared to the results obtained for porphyry and diabase aggregates. However, this does not limit the possibility of using the aggregate based on steel slags, as according to the applicable WT-4 and WT-5 standards, it can be used in mixtures unbound to the improved subsoil and layers of the road foundation as well as road mixtures with hydraulic binders for each category of traffic load. The chemical composition of the aggregate based on steel slags differs from the chemical composition of the tested natural aggregates. The slags contain lower amounts of SiO2 and Al2O3, while the concentration of CaO and Fe2O3 is greater. Additionally, heavy metals have also been exhibited in the slags. However, it was established that the alkaline nature of the slags, which is affected by low sulphur content and a significant proportion of CaO, as well as the way the metals occur limit the possibility of heavy metals release and migration from slags. The tested steel slags may constitute a prospective material used in road construction.
This paper deals with issues related to tribological processes occurring as a result of excessive wear of the surface of scraper conveyor components caused by the impact of the mined material created during drilling of development or exploitation galleries. One of the most common types of tribological wear is abrasive wear. W ear tests were carried out for hard coal – based abrasive using dry carbon abrasive and a hydrated mixture with 76 and 58% hard coal. Based on the conducted research, it was established that the effects of wear processes are associated with damage typical of wear mechanisms: micro-scratching and micro-fatigue. For the wear variant in the presence of dry coal abrasive, individual scratches caused by the abrasive grains were observed on the surface of the samples. The main reason for this type of damage was the aggregation of quartz, which is one of the basic components of the mineral substance present in the tested hard coal. When hydrated carbon mixtures were used as an abrasive, the surface of the samples also displayed scratches characteristic of the aggregate quartz. A small part of the carbon abrasive was pressed into the scratches. Under the influence of the wear caused by friction, small depressions were also formed, where coal penetrated. The effect of coal pressing into micro-scratches is related to its plastic properties. T ests of the abrasive conducted after the conclusion of wear tests have shown that under the influence of the local increase in temperature and pressure, the hard coal contained in the abrasive can undergo transformations. In the abrasive transformed under friction, small, but measurable changes in the content of the C element in relation to the initial hard coal sample were exhibited.