Flexural optimization of slag-based geopolymer concrete beams modified with corn cob ash

Abstract

This study investigated the flexural strength of geopolymer concrete (GPC) beams produced with ground granulated blast furnace slag (GGBFS) and corn cob ash (CCA). The design of experiment (DOE), Box-Behnken design (BBD) of the response surface methodology (RSM), was used to optimize the strength. GGBFS was replaced at 0, 20, and 40 wt. % of CCA. The mixes were activated with 14 molar concentration (14 M) of both sodium silicate (Na2SiO3) and sodium hydroxide (NaOH) solutions. The mix design properties such as alkaline liquid to binder ratio, binder to aggregate ratio, binder ratio, and curing time were statistically applied as continuous (independent) variables to optimize the response factor (flexural strength). Compared with the control sample (Portland cement concrete), GPC exhibited higher compressive and flexural strengths at up to 40 wt. % of CCA replacement. The models predicted the response of flexural strength with less than 5% variability. Besides, the correlation between the experimental and the optimized flexural strength yielded a high precision with 99.6% "R 2 ". Therefore, this study's response models would be advantageous in the optimization of mix design proportions for obtaining target flexural strength of GPC beams produced with GGBFS and CCA.

Effect of Artificial Fibers and Corn Cob Ash on Mechanical Behavior of High Performance Concrete

“…It has been observed that the PS4 mix enhanced flexural strength about 37.02%, 11.78% and 17.10% at 7, 14 and 28 days, respectively. This enhancement in flexural strength attribute due to the coupling effect of CCA and fibers, which leads to even distribution fibers inside cement matrix and arrests crack of HPC [7,24].…”

“…The replacement of 15% CCA and 0.4% of PS fiber was enhanced the split tensile strength about 10.63%, 0.26% and 18.20% at age of 7, 14 and 28 days, respectively. This mainly attributed due to the inclusion of CCA and artificial fibers can reduce the interconnectivity of pores in cement matrix [40][41][42] and also enhance denser microstructure through even distribution of fibers [18,24]. Consequently, this process enhanced friction coefficient between fiber and cement matrix, which leads to improve the tensile strength by arrests cracks and interlocking of slip planes.…”

“…The replacement of CCA was improved the durability characteristics of self-compacting concrete [9,23]. CCA replacement increased the flexural strength of geopolymer concrete beams [24]. Still, now only few studies were available in the usage of CCA in HPC.…”

Cement-Based Concrete Modified with Vitellaria Paradoxa Ash: A Lifecycle Assessment

“…The concrete compressive strength (fc) was tested at 28 days of curing, following the BS EN 12390-3 [72] 's procedure and relevant studies [73][74][75] via the 2000 kN maximum capacity compressive testing machine, Model: YES 2000. For the analysis, an average of three samples crushed was used.…”

Influence of Rice Straw Ash on Workability and Strength of Concrete

“…These wastes include but are not limited to corn cob, anacardium occidentale nutshell, groundnut shell, rice husk and straw which are used as pozzolanas in concrete production. Study by [17][18][19][20][21][22][23] has confirmed the suitability of corn cob ash, anacardium occidentale nutshell ash, and groundnut shell ash as pozzolanas in Concrete production. Also, studies by [24][25][26][27] have shown the effectiveness of rice husk ash (RHA) as Ordinary Portland cement substitute for making durable concrete.…”