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Obstojnost betonov različnih sestav s kontroliranim razvojem lastnosti : magistrsko delo
Kvrgić, Sanja (Author), Bokan-Bosiljkov, Violeta (Mentor) More about this mentor... This link opens in a new window, Reščić, Lojzka (Co-mentor)

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Abstract
Namen magistrske naloge je preverjanje obstojnosti različnih betonov in malt, ki so podvrženi agresivnim pogojem okolja, z vzporednim nenehnim preverjanjem nekaterih mehanskih in fizikalnih lastnosti (s kontroliranim razvojem lastnosti). Kontrolirane mehanske lastnosti betonov in malt zajemajo tlačno, upogibno in cepilno natezno trdnost ter dinamični modul elastičnosti. Skupno betonom in maltam so enake sestavine in vodo-cementno razmerje, ki znaša 0,45, pri čemer malta ne vsebuje grobega agregata. V ta namen smo v okviru magistrske naloge preučevali vpliv kemijske alkalno-karbonatne reakcije (ACR) na mehanske lastnosti, spremembo mase in dolžine maltnih vzorcev. Malte so bile pripravljene iz štirih različnih karbonatnih agregatov nazivne frakcije 0/4 mm v kombinaciji z dvema različnima cementoma. Preizkušanci v obliki prizem (40x40x160 mm) so bili skozi obdobje 14 mesecev izpostavljeni različnim pospešenim pogojem staranja (deionizirani vodi ali 1 M raztopini natrijevega hidroksida pri temperaturi 20 °C ali 60 °C). Na betonih smo preverjali njihovo odpornost v primeru ciklične obtežbe zmrzovanja in tajanja, vse do 250 ciklov. Vzporedno smo določili tudi njihovo tlačno trdnost, cepilno natezno trdnost in odpornost proti prodoru vode, vendar v tem primeru samo pred začetkom obremenjevanja s cikli zmrzovanja/tajanja, katerih vpliv smo preverjali s pomočjo določitve dinamičnega modula elastičnosti betona. Ugotovili smo, da ACR vpliva na mehanske lastnosti dolomitnih malt, ne pa tudi na njihovo spremembo mase in dolžine, zato smo zaključili, da ACR ni ekspanzijska reakcija. Prav tako smo pokazali, da imajo vsi obravnavani betoni visoko odpornost proti zmrzovanju/tajanju in visoko vodotesnost, kar pomeni, da smo zasnovali betonske mešanice, ki so sposobne zagotavljati dolgo življenjsko dobo armiranobetonskih elementov – tudi 200 let in več.

Language:Slovenian
Keywords:obstojnost betonov in malt, alkalno-karbonatna reakcija (ACR), notranja odpornost proti zmrzovanju/tajanju (NOZT), tlačna trdnost, upogibna trdnost, cepilna natezna trdnost, dinamični modul elastičnosti
Work type:Master's thesis/paper (mb22)
Tipology:2.09 - Master's Thesis
Organization:FGG - Faculty of Civil and Geodetic Engineering
Year:2017
Publisher:[S. Kvrgić]
UDC:691.32+691.53(043.3)
COBISS.SI-ID:8214369 Link is opened in a new window
Views:602
Downloads:822
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Secondary language

Language:English
Title:Durability of concretes of different mixture designs with controlled development of its properties : Master's thesis
Abstract:
The purpose of the master's thesis is to verify the durability of concretes and mortars that are exposed to aggressive environmental conditions, with controlled development of their physical and mechanical properties. Controlled mechanical properties of concretes and mortars are compressive, bending and splitting tensile strength and dynamic modulus of elasticity. What the concretes and mortars have in common are the same components and a water-cement ratio of 0,45, where mortars do not contain coarse aggregates. In this thesis, we try to establish the impact of the chemical alkali-carbonate reaction (ACR) on mechanical properties, weight and length of mortar samples. The mortars were made with four different carbonate aggregates with the nominal fraction 0/4 m, and by combining two different cements. The prism-shaped samples (40x40x160 mm) were exposed to different accelerated ageing conditions over a period of 14 months (a solution of deionised water or 1 mol sodium hydroxide, and a temperature of 20 °C or 60 °C). We also tested the resistance of the concrete samples in the case of a cyclic freezing and thawing load, up to 250 cycles. Before the freezing/thawing test, we also tested their mechanical properties. We determined their pressure strength, splitting tensile strength and resistance to water penetration. However, we performed these tests before the start of loading freeze/thaw cycles, the influence of which was checked by determining the dynamic modulus of elasticity of concrete. The results have shown that ACR affects mechanical properties of dolomite mortar samples, but not their mass and length. Therefore, we have concluded that ACR is not an expansion reaction. We have also determined a high resistance to freezing/thawing and high watertightness of all concrete samples. This means that we have designed concrete mixtures that are capable of providing a long lifespan of reinforced concrete elements, even up to 200 years and more.

Keywords:concrete and mortars durability, alkali-carbonate reaction (ACR), internal resistance to freezing/thawing, compressive strength, flexural strength, splitting tensile strength, dynamic modulus of elasticity

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