scholarly journals Enhancing corrosion resistance of RC pipes using geopolymer mixes when subjected to aggressive environment

2022 ◽  
Vol 69 (1) ◽  
Author(s):  
Lamiaa M. Omer ◽  
Mohamed S. Gomaa ◽  
Waleed H. Sufe ◽  
Alaa A. Elsayed ◽  
Hany A. Elghazaly

AbstractThe durability of reinforced concrete (RC) pipes depends upon the corrosion resistance of the reinforcing steel and the resistance of concrete mixes against an aggressive environment. This research paper aims to compare the performance of R.C. pipes made of ordinary Portland cement (OPC) concrete mixtures with others made of two different geopolymer concrete mixes based on different ratios of granulated blast furnace slag (GBFS), fly ash (FA), and pulverized red brick (RB) subjected to three different environments, ambient, tap water (TW), and an aggressive environment, and a solution of 10% magnesium sulfates + 5% chloride (MS-CL). An accelerated corrosion setup has been applied to accelerate the corrosion process in the tested samples. The evaluation of change of compressive strength of concrete and microstructure of different mixes was investigated too. Fourier transform infrared (FTIR) spectroscopy has been studied on all pipes. Geopolymer concrete mixes based on 90% GBFS and 10% RB show better results in all cases. Geopolymer concrete mixes based on 63% GBFS, 27% FA, and 10% RB increase the concrete compressive strength in the magnesium sulfate and chloride environment by 5% compared to tap water. It can be concluded that the geopolymer concrete mixes produced of 90% GBFS and 10% RB perform well under all environments, and its microstructure shows stable behavior in an aggressive environment.

This paper aims to investigate the influence of alkaline activators solution i.e, Na2SiO3 / NaOH on compressive strength of geopolymer concrete mixed with Ground Granulated Blast furnace slag (GGBS) for constant molarity 8 M. The ratio of alkali to binder ratio is taken as 0.5 and the ratio of Na2SiO3 / NaOH is 2.5. The geopolymer mix is based on pervious sutdies. As per Indian standard size moulds for the cube, cylinder and prism are cast, cured and tested.The specimens were tested for fresh concrete properties such as slump cone test and hardened properties such as compressive strength for cubes, split tensile strength for cylinders and flexural strength for prism different days of curing under ambient temperature. Also, a microstructural study is done by using Scanning electron microscopy (SEM), Energy dispersive X-ray (EDX) for the tested sample. It is found from the test results that, with the aid of alumino-silicate solution, early strength is achieved by geopolymer concrete within 7 days under ambient condition due to the presence of ground granulated slag.


2017 ◽  
Vol 79 (3) ◽  
Author(s):  
Habeeb Lateef Muttashar ◽  
Mohd Warid Hussin ◽  
Mohd Azreen Mohd Ariffin ◽  
Jahangir Mirza ◽  
Nor Hasanah ◽  
...  

Millions of tons of spent garnet, a by-product of surface treatment operations, are disposed of in landfills, oceans, rivers, and quarries, among others every year, thus it causes environmental problems. The main objective of this study is to evaluate spent garnet as a sand replacement in concrete prepared with ground granulated blast furnace slag (GGBS)-based self-compacting geopolymer concrete (SCGC). Concrete mixtures containing 0%, 25%, 50%, 75% and 100% spent garnet as a replacement for river sand were prepared with a constant Liquid/Binder (L/B) mass ratio equal to 0.4. Compressive, flexural and splitting tensile strengths as well as workability tests (slump, L-box, U-box and T50) were conducted on concrete containing spent garnet. As per specification and guidelines for self-compacting concrete (EFNARC) standard, the test results showed that the concrete’s workability increased with the increase of spent garnet, while all the other strength values were consistently lower than conventional concrete (SCGC) at all stages of replacement. The results recommended that spent garnet should be used in concrete as a sand replacement up to 25% to reduce environmental problems, costs and the depletion of natural resources.


2021 ◽  
Vol 11 (7) ◽  
pp. 3041
Author(s):  
Habib H. Alqamish ◽  
Adil K. Al-Tamimi

In the last decade, nanomaterials made a major breakthrough in the concrete industry by providing the concrete with unique properties. Earlier studies have shown improvement in the early strength of concrete that can accelerate the construction process. In this study, 1% and 2% of nano-silica were added to concrete mixtures that contain 30% and 70% ground granulated blast-furnace slag (GGBS). Adding 1% of nano-silica to the 30% GGBS mixture showed an increase in the compressive strength by 13.5%, 7.8%, 8.1%, and 2.2% at one day, three days, seven days, and twenty-eight days, respectively. The 2% of nano-silica increased the 30% GGBS mixture’s compressive strength less effectively by 4.3%, 7.6%, and 4.9% at three days, seven days, and 28 days, respectively, when compared to the 1%. On the other hand, adding 1% and 2% of nano-silica reduced the 70% GGBS mixtures’ compressive strength. Moreover, nano-silica reduced the deformability of the mixtures significantly, which caused the increase in the Young’s modulus. The flexural strength of the 30% GGBS mixtures had similar behavior as the 28-day compressive strength. On the other hand, the flexural strength of the 70% GGBS mixtures increased as the nano-silica increased. Nano-silica addition improved the microstructure and the interface structure of the mixtures due to its high pozzolanic activity and the nano-filler effect, which is confirmed by RCPT results and SEM images.


2020 ◽  
Vol 18 (2) ◽  
pp. 205-218
Author(s):  
A. Serag Faried ◽  
W. H. Sofi ◽  
Al-Zahraa Taha ◽  
Magdy A. El-Yamani ◽  
Taher A. Tawfik

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1279
Author(s):  
Sundaravadivelu Karthik ◽  
Kaliyaperumal Saravana Raja Mohan

In recent decades, geopolymer concrete (GPC) has been extensively researched as a potential substitute sustainable building material that may reduce CO2 emissions due to its utilization of industrial by-products. Fly ash (FA) and ground-granulated blast-furnace slag (GGBFS) are preferred geopolymer raw materials due to their obtainability and high alumina and silica concentrations. GGBFS-FA based GPC offers a clean and sustainable development technology alternative. In this study, the Taguchi method was used to optimize the mixed proportions of geopolymer concrete to achieve desired strength criteria. Four factors and four levels were considered: binder content, including four combinations of FA and GGFBS dosage, dosage of superplasticizer (0.5, 1.0, 1.5 and 2%), Na2SiO3/NaOH ratio (1.5, 2.0, 2.5 and 3), and molarity (6, 8, 10 and 12). Using these ingredients and factors, the effect of compressive strength was examined. The Taguchi approach using an L16 orthogonal array was employed to find the optimum condition of every factor while limiting the number of experiments. The findings indicated that the optimum synthesis conditions for maximum compressive strength obtained from the binder comprised 45% of FA, 45% of GGBFS and 10% of silica fume, 1.5% dosage of superplasticizer, Na2SiO3/NaOH ratio = 1.5, and 12 molar contents.


2020 ◽  
Vol 26 (4) ◽  
pp. 477-481
Author(s):  
Parthiban KATHIRVEL ◽  
Murali GUNASEKARAN ◽  
Sreenath SREEKUMARAN ◽  
Arathi KRISHNA

The study on the characteristics of geopolymer concrete (GPC) is of ultimate significance to instill assurance in builders and engineers. Abundant available literatures point towards the utilization of fly ash and ground granulated blast furnace slag (GGBFS) as source material in the production of GPC with little on other materials. India produces nearly 350 MMT of sugarcane for the production of sugar, which lies second only to Brazil in the annual production, the disposal of the bagasse creates an environmental issue needs to be effectively utilized. Hence, this work was intended to investigate the effect of utilizing sugarcane bagasse ash (SCBA) as a source material in the production of geopolymer mixes. The fresh (consistency, setting time, soundness and flow), hardened (density, compressive strength, expansion and pH) and microstructural properties (X-ray diffraction) of the tested mixes were asessed. The results infer that 20 % replacement level of GGBFS with SCBA produces superior compressive strength and all other results were within the permissible limits even at 40 % replacement level.


2017 ◽  
Vol 68 (6) ◽  
pp. 1182-1187
Author(s):  
Ilenuta Severin ◽  
Maria Vlad

This article presents the influence of the properties of the materials in the geopolymeric mixture, ground granulated blast furnace slag (GGBFS) + wheat straw ash (WSA) + uncalcined red mud (RMu), and ground granulated blast furnace slag + wheat straw ash + calcined red mud (RMc), over the microstructure and mechanical properties of the synthesised geopolymers. The activation solutions used were a NaOH solution with 8M concentration, and a solution realised from 50%wt NaOH and 50%wt Na2SiO3. The samples were analysed: from the microstructural point of view through SEM microscopy; the chemical composition was determined through EDX analysis; and the compressive strength tests was done for samples tested at 7 and 28 days, respectively. The SEM micrographies of the geopolymers have highlighted a complex structure and an variable compressive strength. Compressive strength varied from 24 MPa in the case of the same recipe obtained from 70% of GGBFS + 25% WSA +5% RMu, alkaline activated with NaOH 8M (7 days testing) to 85 MPa in the case of the recipe but replacing RMu with RMc with calcined red mud, alkaline activated with the 50%wt NaOH and 50%wt Na2SiO3 solution (28 days testing). This variation in the sense of the rise in compressive strength can be attributed to the difference in reactivity of the materials used in the recipes, the curing period, the geopolymers structure, and the presence of a lower or higher rate of pores, as well as the alkalinity and the nature of the activation solutions used.


2010 ◽  
Vol 64 ◽  
pp. 19-24
Author(s):  
H.H. Seleem ◽  
A.M. Rashad ◽  
B.A. El-Sabbagh

The current work reports the influence of synthetic seawater on some of the durability aspects of an ordinary concrete mixture (control) and six pozzolan-concrete mixtures. Three types of pozzolanic materials were employed; silica fume (SF), ground granulated blast furnace slag (GGBS) and metakaolin (MK). The pozzolanic materials were employed as an addition to cement in binary and ternary combinations. All mixtures were tested for strength deterioration ratio (SDR) after 3, 6, and 12 months of exposure to synthetic seawater, permeability was measured after 6 and 12 months of exposure. It was found through this investigation that pozzolans increase the ability of concrete to withstand aggressive environment and prevent most of the deterioration signs. The pozzolanic materials serve also to increase the strength and to minimize the strength loss (SDR) upon exposure to seawater. The pozzolanic materials led to reduce concrete permeability compared to control.


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7109
Author(s):  
Wei Yang ◽  
Pinghua Zhu ◽  
Hui Liu ◽  
Xinjie Wang ◽  
Wei Ge ◽  
...  

Geopolymer binder is expected to be an optimum alternative to Portland cement due to its excellent engineering properties of high strength, acid corrosion resistance, low permeability, good chemical resistance, and excellent fire resistance. To study the sulfuric acid corrosion resistance of geopolymer concrete (GPC) with different binding materials and concentrations of sodium hydroxide solution (NaOH), metakaolin, high-calcium fly ash, and low-calcium fly ash were chosen as binding materials of GPC for the geopolymerization process. A mixture of sodium silicate solution (Na2SiO3) and NaOH solution with different concentrations (8 M and 12 M) was selected as the alkaline activator with a ratio (Na2SiO3/NaOH) of 1.5. GPC specimens were immersed in the sulfuric acid solution with the pH value of 1 for 6 days and then naturally dried for 1 day until 98 days. The macroscopic properties of GPC were characterized by visual appearance, compressive strength, mass loss, and neutralization depth. The materials were characterized by SEM, XRD, and FTIR. The results indicated that at the immersion time of 28 d, the compressive strength of two types of fly ash-based GPC increased to some extent due to the presence of gypsum, but this phenomenon was not observed in metakaolin-based GPC. After 98 d of immersion, the residual strength of fly ash based GPC was still higher, which reached more than 25 MPa, while the metakaolin-based GPC failed. Furthermore, due to the rigid 3D networks of aluminosilicate in fly ash-based GPC, the mass of all GPC decreased slightly during the immersion period, and then tended to be stable in the later period. On the contrary, in metakaolin-based GPC, the incomplete geopolymerization led to the compressive strength being too low to meet the application of practical engineering. In addition, the compressive strength of GPC activated by 12 M NaOH was higher than the GPC activated by 8 M NaOH, which is owing to the formation of gel depended on the concentration of alkali OH ion, low NaOH concentration weakened chemical reaction, and reduced compressive strength. Additionally, according to the testing results of neutralization depth, the neutralization depth of high-calcium fly ash-based GPC activated by 12 M NaOH suffered acid attack for 98 d was only 6.9 mm, which is the minimum value. Therefore, the best performance was observed in GPC prepared with high-calcium fly ash and 12 M NaOH solution, which is attributed to gypsum crystals that block the pores of the specimen and improve the microstructure of GPC, inhibiting further corrosion of sulfuric acid.


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