Effect of parameters on the compressive strength of fly ash based geopolymer concrete

In this study, mechanical, visual, and microstructure changes of geopolymer concrete exposed to sulfate and salt effects were investigated. Elazı g ferrochrome slag (EFS) and blast furnace slag (BFS)-based geopolymer concretes which completed curing time were immersed in 5% sodium sulfate (Na 2 SO 4 ), magnesium sulfate (MgSO 4 ), sodium chloride (NaCl), and magnesium chloride (MgCl 2 ) solutions for 12 weeks. The compressive strength values, ultrasonic pulse velocities, visual inspections, weight, and length changes of the samples were determined in this investigation. In addition, scanning electron microscopy was performed for the microstructure analysis of the samples removed from the solutions. Sulfate solutions had a more negative effect on the samples than salt solutions. As the EFS ratio in the mixture increases, the loss rate in the strength of the samples exposed to sulfate and salt solutions decreased. While samples exposed to sodium chloride, sodium sulfate, and magnesium sulfate solutions occurred weight gain, samples exposed to magnesium chloride occurred weight loss. The samples in salt solutions shrank, while the samples in sulfate solutions expanded. No deterioration occurred on the surfaces of the samples exposed to the solutions for 12 weeks. K E Y W O R D S blast furnace slag, chemical resistance, ferrochrome slag, geopolymer concrete, salt effect, sulfate effect

Section: Introductionmentioning

confidence: 99%

Evaluation of sulfate and salt resistance of ferrochrome slag and blast furnace slag‐based geopolymer concretes

Özcan

Karakoç

2019

“…Research findings over the past 10 years revealed that fresh and hardened properties of GP concrete were affected the composition of alkaline activators and their content relative to binding materials, aggregates contents, and sodium hydroxide molarity as well as curing temperature and period . The type and composition of base materials or their blend have crucial impacts upon the polymerization extent of GP composites, hence its internal structure .…”

Section: Generalmentioning

confidence: 99%

“…The above outlined literature works revealed that the potential of using OSA, as a base material in the production of GP composites, was merely investigated, if none . This work aimed at studying the potential of producing geopolymer mortar (GPM) using Jordanian OSA; considering inherent key parameters, namely concentration of catalysis materials, and alkaline/binder ratios; where the binder (B) represents the solid consistent of sodium hydroxide (NH), sodium silicate (NS), and OSA, and water represents the sum of water in alkaline solutions and water added to maintain consistency.…”

Section: Generalmentioning

confidence: 99%

Producing geopolymer composites using oil shale ash

Haddad

Ashteyat

Lababneh

2018

The potential of producing geopolymer (GP) composites using Jordanian oil shale ash (OSA) was investigated. Twelve GP mortar mixtures were prepared using OSA and different proportions of commercially available alkaline activator, composed of sodium silicate and sodium hydroxide. Prismatic specimens (40 × 40 × 160 mm), attained satisfactory workability, were left at laboratory air for 24 hr, then demolded and dry cured at different practical temperatures (60-100 C) for 24 and 48 hr before left in laboratory air and finally tested for strength and capillary porosity. Furthermore, SEM analysis was carried out on matured GP mortar samples to determine the extent of OSA polymerization and status of pore system. The results indicated the potential of producing GP mortar using OSA with strength grades of as high as 20 MPa. Dry curing at 60 C for 24 hr imparted the best mechanical and durability properties of OSA-based GP mortar. The internal pore structure showed excellent correlation with mechanical and durability properties of produced GP composites. K E Y W O R D S concrete, geopolymer, OSA, porosity, SEM, strength

“…Plastic shrinkage refers to the volume change due to the evaporation of water from the concrete paste in the fresh state during the hardening process, and drying shrinkage is caused by internal water evaporation from the matrix due to low external environmental humidity of the cement‐based materials after hardening of cement . For the last two decades, there have been numerous published studies on the use of admixtures as a supplementary cementitious material to improve the mechanical performance and resist shrinkage ability of concrete . It could be concluded that cement with admixtures has a lower permeability due to the formation of calcium silicate hydrate (C‐S‐H) than that of Portland cement .…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the compressive strength and shrinkage of concrete containing fly ash and ground granulated blast‐furnace slag

Zhang

2019

This paper presents an experimental investigation on the compressive strength and shrinkage (drying shrinkage and plastic shrinkage) property of concrete specimens with fly ash (FA) and ground granulated blast-furnace slag (GGBS), and moreover, the content level and curing age were considered in this experiment. The resultsshow that the addition of FA and GGBS has a significant effect on the compressive strength and shrinkage properties of concrete. It indicated that the compressive strength of specimens decreases gradually due to the reduction of cement hydration products, when the curing age is less than 14 days. Nevertheless, once the curing time exceeds 7 days, the compressive strength increases initially and then decreases. Similarly, the compressive strength of concrete with GGBS increases slightly at first and then decreases, when the content level exceeds the critical value. The variety rule of plastic shrinkage cracks with FA and GGBS is similar to that of compressive strength; however, the variety rule of drying shrinkage strain is contrary to the above experimental results. Furthermore, in the early stage of curing, the GGBS is the main factor on improving strength and drying shrinkage properties, though for the later stage, the FA becomes the main factor instead of GGBS. K E Y W O R D S compressive strength, drying shrinkage, fly ash, ground granulated blast-furnace slag, plastic shrinkage