Development of fly ash/slag based self-compacting geopolymer concrete using nano-silica and steel fiber

• Published in: Construction & building materials Vol. 211; pp. 271 - 283
• Main Authors: Gülşan, Mehmet Eren, Alzeebaree, Radhwan, Rasheed, Ayad Ali, Niş, Anıl, Kurtoğlu, Ahmet Emin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.06.2019; Reed Business Information, Inc. (US)
• Subjects: Bonding strength; Fiber reinforced concrete; Flexural toughness; Fly ash; Fresh state properties; Mechanical properties; Nano silica; Polymer concrete; Self-compacting geopolymer concrete (SCGC); Silicon dioxide; Steel fiber; Bonding strength; Steel fiber; Fresh state properties; Flexural toughness; Nano silica; Self-compacting geopolymer concrete (SCGC)
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2019.03.228

•Simultaneous use of nanosilica(NS) and steel fiber(SF) improves flexural properties.•All self compacting geopolymer concrete mixes (SCGC) were in VS2/VF2 viscosity class.•Mixes including NS were observed to be more cohesive than mixes without NS.•Simultaneous use of NS and SF did not reduce compressive strength of SCGC specimens.•Statistical analysis showed amount of influence of SF and NS on properties of SCGC. This study investigates the simultaneous effect of nano-silica and steel fiber on the fresh and hardened state performance of self-compacting geopolymer concretes (SCGC). For this purpose, self-compacting geopolymer concretes without and with nano-silica (0, 1% and 2%), and without and with steel fiber (0, 0.5% and 1%) were produced. Hooked-end steel fibers were used with a length of 30 mm and an aspect ratio of 40. Self-compacting geopolymer mixes were produced using 50% fly ash (FA) and 50% ground granulated blast furnace slag (GGBFS) with a constant alkaline activator to binder ratio of 0.5. For the alkaline activator, sodium silicate solution (Na2SiO3) and sodium hydroxide solution (NaOH) were utilized with a ratio (Na2SiO3/NaOH) of 2.5. Fresh state experiments were carried out via slump flow, L-Box, and V-funnel tests, while hardened state experiments were conducted using compressive strength, flexural strength, and bonding strength tests to estimate the effects of nano-silica and steel fiber together on the resulting performances of SCGC specimens. Test results were also evaluated statistically in order to clarify the contributions of the important parameters on the resulting performance. Moreover, correlations between the experimental data were studied to investigate the relationships between the fresh and hardened state performances. The results demonstrated that incorporation of nano-silica and steel fiber affected the fresh state properties adversely; however, a combined utilization of them improved bond strength and flexural performance of the SCGC specimens significantly. In addition, the effect of nano-silica was found to be dominant on fresh state properties and compressive strength, while the effect of steel fiber was found to be superior on flexural performance and bonding strength.