Application of nitrogen gas adsorption for analysis of cemetntitious composites

Metoda apsorpcije dušika (eng. nitrogen gas adsorption) je ispitivanje koje se vrši kod analize cementnih kompozita. Dvije su osnovne primjene za analizu: 1) specifične površine i veličine čestica rastresitih materijala, poput cementa, 2) strukture pore poroznih materijala, poput očvrsnule cementne paste, morta ili betona. Kod prve primjene metoda apsorpcije dušika alternativna je Blaineovoj metodi koja je najraširenija i najkorištenija u cementnoj industriji. Međutim Blaineova metoda ima dosta ograničenja koja mogu utjecati na točnost podataka koje daje. Kod druge primjene, alternativna metoda za analizu strukture pora je živina porozimetrija, pri čemu je ograničenje sigurnost korištenja, te nemogućnost mjerenja prodiranja žive u pore manje od nekoliko nanometara. U ovome radu pobliže je objašnjena metoda apsorpcije dušika i prikazane su njene prednosti i nedostatci u odnosu na druga ispitivanja koja se uobičajeno koriste za istu svrhu. Posebno je objašnjena tehnika pripreme uzoraka i ispitivanja, ali i teoretska pozadina s odgovarajućim pojašnjenjima svih pojava i elemenata.The nitrogen gas adsorption method is a test performed in the analysis of cement composites. There are two basic applications for analysis: 1) specific surfaces and particle sizes of fine grained materials, such as cement, 2) pore structures of porous materials, such as hardened cement paste, mortar or concrete. In the first application, the nitrogen absorption method is an alternative to the Blaine method, which is the most widespread and most widely used in the cement industry. However, Blaine's method has many limitations that can affect the accuracy of the data it provides. In another application, an alternative method for analyzing the structure of the pores is mercury porosimetry, where the limitation is the safety of use, and the inability to measure the penetration of mercury into the pores of less than a few nanometers. In this thesis, the method of nitrogen absorption is explained in more detail and advantages and disadvantages in relation to other tests used for the same purpose are presented. The technique of sample preparation and testing is especially explained, but also the theoretical background with appropriate explanations of all phenomena and elements