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

Abstract

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.