The existing hot water supply system of a 17-storey apartment building commissioned in 2010 is considered and its scheme is described. A laboratory study of the dismantled sections of the defective pipeline was carried out. It is shown that the entire inner surface of the pipe is covered with longitudinal cracks of uneven shape, different lengths and depths. A microscopic examination of the pipe section revealed areas of insufficient adhesion of the reinforcing layer with the inner layer of the polypropylene pipe. It is established that the main reason for the appearance of pipe defects in the form of numerous cracks, the formation of bubbles and fracture with a short service life is associated with the formation of a rupture of bonds between layers and the use of low-quality polypropylene pipes.
Keywords: pipe, polypropylene, defect, crack, swelling, water supply, reinforcing layer, technology, construction, aluminum
The main features of the technology of continuous basalt fiber production at the «NPO Vulkan» (LLC, Perm, Russia) are given. As raw materials the study has been used CEM I 42,5 N (activity 45,1 MPa), natural sand with a fineness modulus of 2.3, gravel of dense gabbro-igneous rocks (size up to 20 mm), basalt fiber length of 6 mm and diameter 11 microns production "NPO Vulcan" (LLC, Perm, Russia). The results of determining the ultimate strength in compression and bending of fine-grained and heavy concrete without the addition of basalt fiber (control composition) and with the addition of fiber 0.1-0.9% by weight of cement are described. It is shown that the optimal limits of the introduction of fiber into the mixture of sand concrete can be considered 0.1-0.2% by weight of cement, which leads to an increase in compressive strength up to 70% and bending strength up to 35%. A further increase in the fiber content to 0.9% leads to a decrease in compressive strength to 27% compared to the control values.
Keywords: basalt fiber, sand concrete, heavy-weight concrete, fiber concrete, continuous fiber, optimization, disperse reinforcement
Results of researches of a ceramic brick are presented. Durability of a brick makes: at compression – more than 10 N/mm2, at a bend – more than 3 N/mm2, water absorption of 10,3%. According to the obtained data the brick conforms to requirements of standards of the Russian Federation. The hypothesis of peeling of a front layer of a brick because of low frost resistance is offered. By results of a X-ray phase research minerals have been identified: quartz, white mica, hydrowhite mica, illit, calcite; existence in a ceramic brick of minerals sillimante and mullite as a result of the phase analysis isn't revealed. Results of the phase analysis are confirmed by data of the thermal analysis. The received results allow to approve about insufficient for formation of minerals sillimante and mullite to temperature of roasting of a ceramic brick. It has exerted impact on decrease in its durability in the conditions of sign-variable temperatures (low frost resistance).
Keywords: face brick, research, brickwork, peel, defect, strength, frost resistance, water absorption, test, mineral