Potential of Natural and Recycled Concrete Aggregate Mixtures for Use in Pavement Structures

This study investigates the feasibility of using recycled concrete aggregate (RCA) as a partial substitution of natural aggregate in pavement engineering. Despite RCA’s good properties, such as polishing value and freeze-thaw resistance, its use is limited by low resistance to fragmentation and high-water absorption. This paper parent the experimental results of mineralogical-petrographic and physical-mechanical properties of RCA, natural stone (dolerite) and their combination (RCA content—15%, 30%, 45%, and 60%). The tested granular mixtures showed good resistance to fragmentation and wear (LA 22–27%, MDE 14–15%), as well as satisfactory Polished Stone Value of 55–57, which means they can be used in different layers of pavement structures. According to the obtained testing results, the application of RCA is possible in different flexible and rigid pavement layers and for various traffic loads.Special Issue: "Minerals and Other Phases in Constructional Geomaterials

Copper Slag of Pyroxene Composition as a Partial Replacement of Natural Aggregate for Concrete Production

Copper slag, a by-product of the pyrometallurgical process used for obtaining copper from copper ore in Bor, Serbia, contains mainly silicon, iron, calcium, and aluminium oxides. Due to such properties, it is disposed of in landfills. Despite the favourable technical properties copper slag aggregates possess, such as low-water absorption (WA24 0.6%), low resistance to fragmentation (LA 10%), and low resistance to wear (MDE 4%), its use in the construction industry is still limited. The results of testing the technical properties of copper slag aggregates (CSAs) as a potential replacement for natural river aggregate (RA) are presented in this paper. The experiments included tests on three concrete mixtures with partial replacement of coarse natural aggregate with copper slag. The replacement of RA particle sizes of 8/16 mm and 16/31.5 mm with CSA in the amount of 20% + 50% and 50% + 50% resulted in an increase in the compressive strength of 12.4% and 10.5%, respectively. The increase of CSA content led to a decrease in water penetration resistance and salt-frost resistance of concrete, whereas the resistance to chloride ion penetration did not change significantly.This article belongs to the Special Issue Applied Petrography of Construction Material

Large myomas as a complicating factor necessitating cesarean myomectomy followed by cesarean hysterectomy

Introduction. Although uterine myomas are becoming more common in pregnancies due to advanced maternal age, the literature lacks reports on complications, such as hysterectomy following cesarean myomectomy (CM). The aim of this work was to describe when CM is inevitable, complicated by severe intrapartum hemorrhage and requiring a hysterectomy. Case outline. A pregnant, with a term pregnancy and large multiple myomas, was referred for elective cesarean section (CS). During the CS, forced enucleation of a 100 mm anterior and left myoma previa (pre-fetal extraction) was necessary, and a 2,800 g neonate was delivered through the lower uterine segment incision. After the delivery and another CM, it was necessary to stop a massive hemorrhage from the myometrial myoma bed. Following provisory suturings of the hysterotomies, an urgent hysterectomy was performed with left salpingo-oophorectomy, due to a large hematoma in the left retroperitoneal space. The patient’s further recovery was uneventful and she was discharged with her baby on the sixth postoperative day. The histopathology report revealed a 135 × 190 × 150 mm uterus, weighing together with the enucleated myomas and left adnexa 5,000 g in total. The weight of the enucleated myomas was 1,670 g. The histopathological examination also showed 12 intramural and subserous myomas in the myometrium, ranging 30–190 mm. Conclusion. Large myomas, especially previa, may present a serious problem for fetal extraction during a CS. Therefore, the authors suggest an informed consent for CM, in patients who should undergo a CS. Additionally, such patients should be counseled about the possibility of an intrapartum hysterectomy