Development and optimisation of curing temperature of energy-efficient geopolymer bricks

U radu prikazan je razvoj održive geopolimerne opeke primjenom maksimalno dopuštenog udjela letećeg pepela i manjom koncentracijom alkalne otopine bez cementa u mješavini, kako bi se u konačnici smanjio negativan utjecaj na okoliš i emisija stakleničkih plinova. Geopolimerne opeke razvijene su primjenom letećeg pepela klase F s korištenjem 2 do 4 M alkalne otopine. Opeka se suši tijekom jednog sata na temperaturi koja varira od 100 do 600 °C. Tlačna čvrstoća takve opeke iznosi 10,2 MPa, a postignuta je u 4 M alkalnoj otopini na temperaturi od 400 °C. Geopolimerna opeka ima kristalnu strukturu i sposobnost toplinske izolacije.Present study focuses on development of a sustainable geopolymer brick in which the use of fly ash is maximised and the concentration of an alkaline solution without cement is reduced, in order to reduce environmental burden and carbon emissions. The geopolymer bricks were developed using the Class F fly ash with 2 to 4 Molar alkaline solution. The bricks were cured for one hour at temperatures ranging from 100 to 600°C. The compressive strength of such bricks amounts to 10.2 MPa and was achieved in the 4-Molar alkaline solution at the curing temperature of 400°C. The geopolymer bricks exhibit crystalline structure and good thermal insulation properties

Sustainable pavement quality concrete containing ultra-high volume fly ash in the presence of a novel superplasticizer

The examination intends to foster a novel blend proportioning for pavement quality concrete (PQC) wherein fly ash (FA) is utilized as a total substitute to river sand (RS). The objective was to utilize FA in a lot higher extent than done in past investigations (more noteworthy than 500 kg/m3). The equivalent was gotten by developing and incorporating a novel superplasticizer (NSP) viable with higher volumes of FA in the concrete blend. In such manner, macromonomers of (poly)ethylene glycol (PEG6000) were added to an industrially accessible high (poly)carboxylate ether (PCE) superplasticizer. This was done in order to increase the adsorption capability of the NSP on to the FA, consequently giving increased strength to the mix. The replacement of river sand with FA was done at 0, 25, 50, 75, and 100 % for M40 grade of concrete and subsequent to achieving the necessary flow in terms of concrete slump, the physio-mechanical properties were evaluated in terms of compressive, flexural and split tensile strengths. Durability studies were additionally carried out in terms of rapid chloride penetrability test (RCPT) and abrasion resistance, alongside microstructural examinations. The samples containing 100 % FA showed a noticeable increase in the 28-days compressive strength of 15 % when contrasted with the control blend. By and large, every one of the preliminaries displayed worthy strength properties according to the codal prerequisites of IS 456: 2000, empowering us to reason that total substitution of river sand in concrete with FA within the sight of NSPs is a maintainable option in contrast to the conventional mix design approach