Browsing by Subject "reinforced concrete"

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Access status: Open Access ,
Atypical solution of a road tunnel Valík
(Wydawnictwa AGH, 2005) Aldorf, Josef; Ďuriš, Lukáš
The contribution informs of advancement for solving the stability of the tunnel Valik reinforced concrete abutment. This concept option was due for lowering the environmental impacts accompanying the tunnel excavation.
Access status: Open Access ,
Microstructural, mechanical and pozzolanic characteristics of metakaolin-based geopolymer
(Wydawnictwa AGH, 2020) Abiodun, Yetunde Oyebolaji; Sadiq, Obanishola Muftau; Odeosun, Samson Oluropo
The use of cement contributes to global $CO_2$ emission and this leads to the depletion of ozone layer, causing global warming. The quest to reduce or eliminate this problem has resulted in the discovery of metakaolin-based geopolymer as an alternative to the use of cement in construction work. In this study, metakaolin obtained as a result of kaolin calcination from some deposits in Nigeria, Ogun (Imeko), Edo (Okpela), Ondo (Ifon) and Ekiti (Isan-Ekiti) were characterized and used to determine the compressive and flexural strength of metakaolin-based geopolymer concrete (Mk-GPC). Cubes of 150 x 150 x 150 mm were used for the compressive strength test and reinforced concrete beams of size 150 x 250 x 2160 mm were produced to test for flexural strength. A water-absorption test was also carried out on Mk-GPC and the effect of ball-milling was assessed on the strength properties. The results from the various tests showed that 800°C for 1 hour of calcination of kaolin gives best combination of performance properties due to the presence of amorphous silica in metakaolin. Mk-GPC gave higher compressive strength and at an early age than ordinary Portland cement (OPC) concrete. The water absorption capacities of Mk-GPC were higher than the control samples. In the flexural strength test, the reinforced beams failed in flexural-shear mode and the shear capacities at 28-, 56- and 90-day curing age of the beams were between 0.656 and 0.938 MPa for Mk-GPC beams and between 0.563 and 0.844 MPa for the control beams. The moment capacities for the beams were between 19.25 and 33.25 (x10$^{3}$ kgm$^{2}$/s$^{2}$) for Mk-GPC beams and were between 22.75 and 28.0 (x10$^{3}$ kgm$^{2}$/s$^{2}$) for the control beams. The study has revealed that metakaolin-based geopolymer can serve as an alternative to cement for sustainable construction in the Nigerian construction industry.
Access status: Open Access ,
Practical application of high resolution ground penetrating radar method inside buildings
(Wydawnictwa AGH, 2012) Mazurek, Ewelina; Łyskowski, Mikołaj
An infrastructure development requires a precise indoor localization plan of cables, pipes or reinforcing elements. Due to the age of many buildings in Poland such plans often do not exist or do not contain the evidence of numerous activities carried out over years like repairs or modifications. Due to this situation demands for application of geophysical methods grow, especially with respect to the Ground Penetrating Radar (GPR) method. A possibility of precise localization of hidden objects arises with the use of high frequency antennas together and with precise measuring grid. Research carried out at the request of one of the departments of AGH University of Science and Technology in building B2 showed great potential of GPR methods in this field. The study was devoted to recognition of structure of the concrete floor. The obtained results gave very precise location of numerous objects of interest and they became a good sample of high resolution investigations. The survey was performed with ProEx unit, produced by a Swedish company - Mala Geoscience, which is in the possession of the Department of Geophysics, Faculty of Geology, Geophysics and Environmental Protection.