2 research outputs found
The influence of metakaolin substitution by slag in alkali-activated inorganic binders for civil engineering
V tĂ©to studii byl zkoumán účinek náhrady metakaolĂnu mletou vysokopecnĂ struskou v alkalickĂ©m geopolymernĂm pojivu z pohledu jejich reologickĂ˝ch a mechanickĂ˝ch vlastnostĂ. Bylo prokázáno, Ĺľe pĹ™idávánĂ strusky do pojiva mĹŻĹľe zlepšit mechanickĂ© vlastnosti koneÄŤnĂ˝ch produktĹŻ. Naše zkoumánĂ bylo zaměřeno na širokĂ˝ interval substituce metakaolinĹŻ v rozmezĂ od 100 do 40 objemovĂ˝ch procent metakaolinu, kdy objem pevnĂ˝ch látek v koneÄŤnĂ©m pojivu zĹŻstal konstantnĂ. PĹ™ipravená pojidla byla aktivována alkalickĂ˝m roztokem kĹ™emiÄŤitanu draselnĂ©ho s kĹ™emiÄŤitanovĂ˝m modulem 1,61. AnalĂ˝zy velikosti částic byly provádÄ›ny pro stanovenĂ distribuce velikosti částic. ReologickĂ© vlastnosti byly stanoveny v souladu s prĹŻtokovĂ˝mi vlastnostmi měřenĂmi na FordovÄ› vĂ˝tokovĂ©m poháru a oscilaÄŤnĂm měřenĂm procesu vytvrzovánĂ. Pro zkoumánĂ procesu vytvrzovánĂ byla v geometrii rovinnĂ˝ch desek pouĹľita oscilaÄŤnĂ reometrie s malou amplitudou Ĺ™Ăzená deformacĂ. Pro stanovenĂ aplikaÄŤnĂch mechanickĂ˝ch vlastnostĂ byly pojiva plnÄ›na keramickĂ˝m ostĹ™ivem v rozmezĂ zrnitosti 0-1 mm. PlnÄ›nĂ bylo udrĹľováno konstantnĂch 275 objemovĂ˝ch procent vzhledem k suchĂ©mu pojivu. MechanickĂ© vlastnosti byly zkoumány po 1, 7 a 28 dnech a mikrostruktura byla dokumentována rastrovacĂ elektronovou mikroskopiĂ. VĂ˝sledky ukazujĂ, Ĺľe pĹ™Ădavek strusky má pĹ™ĂznivĂ˝ účinek nejen na mechanickĂ© vlastnosti tvrzenĂ©ho pojiva, ale takĂ© na tokovĂ© vlastnosti ÄŤerstvĂ© geopolymernĂ pasty a následnĂ© kinetiky vytvrzenĂ alkalicky aktivovanĂ˝ch pojiv.In this study the effect of metakaolin replacement by milled blast furnace slag in alkali-activated geopolymeric binder was investigated in accordance to their rheological and mechanical properties. It was demonstrated that slag addition into the metakaolin binder can improve mechanical properties of final products. Our investigation was focused on broad interval of metakaolin substitution in the range from 100 to 40 volume per cents of metakaolin so that the volume content of solids in final binder was maintained constant. Prepared binders were activated by alkaline solution of potassium silicate with silicate module of 1.61. The particle size analyses were performed for determination of particle size distribution. The rheological properties were determined in accordance to flow properties by measurements on Ford viscosity cup and by oscillatory measurements of hardening process. For the investigation of hardening process, the strain controlled small amplitude oscillatory rheometry was used in plane-plate geometry. For determination of applied mechanical properties were binders filled by ceramic grog in the granularity range 0-1 mm. The filling was maintained constant at 275 volume per cents in accordance to ratio of solids in dry binder. The mechanical properties were investigated after 1, 7 and 28 days and microstructure was documented by scanning electron microscopy. The results indicate that slag addition have beneficial effect not only on mechanical properties of hardened binder but also on flow properties of fresh geopolymer paste and subsequent hardening kinetics of alkali-activated binders