scholarly journals The Effect of Ordinary Portland Cement Substitution on the Thermal Stability of Geopolymer Concrete

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2501 ◽  
Author(s):  
Hongen Zhang ◽  
Lang Li ◽  
Tao Long ◽  
Prabir Sarker ◽  
Xiaoshuang Shi ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Residual Strength ◽  
Geopolymer Concrete ◽  
Sem Images ◽  
Sodium Aluminosilicate ◽  
Residual Properties ◽  
Original Strength ◽  
Sodium Aluminosilicate Hydrate ◽  
Heating Up

The influence of using cement on the residual properties of fly ash geopolymer concrete (FAGC) after exposure to high temperature of up to 800 °C was studied in terms of mass loss, residual compressive strength and microstructure. The mass loss was found to increase with the increase of exposure temperature, which is attributed to vaporization of water and dehydroxylation of sodium aluminosilicate hydrate (N-A-S-H) gels. The dehydroxylation of calcium silicate hydrate (C-S-H) gels and the disintegration of portlandite were responsible for higher mass loss ratio of FAGCs containing cement. The results showed that cement could increase compressive strength of FAGCs up to 200 °C, after which a significant reduction in residual strength was observed. It was found that FAGCs without cement yielded higher residual strength than the original strength after heating up to 600 °C. The observed increase of compressive strength up to 200 °C was attributed to the secondary geopolymerization which was evidenced in the scanning electronic microscopy (SEM) images.

scholarly journals The Effect of Alkaline Activator Types on Strength and Microstructural Properties of Geopolymer from Co-Combustion Residuals of Bamboo and Kaolin

2018 ◽  
Vol 18 (3) ◽  
pp. 397 ◽  
Author(s):  
Aprilina Purbasari ◽  
Tjokorde Walmiki Samadhi ◽  
Yazid Bindar
Keyword(s):  
Compressive Strength ◽  
Water Glass ◽  
Curing Temperature ◽  
Sem Images ◽  
Homogeneous Microstructure ◽  
Sodium Aluminosilicate ◽  
Naoh Solution ◽  
Alkaline Activator ◽  
Xrd Patterns ◽  
Sodium Aluminosilicate Hydrate

Geopolymer as a Portland cement substitute had been synthesized from alkaline activation of co-combustion residuals of bamboo and kaolin. Types of used alkaline activators were NaOH solution, KOH solution, a mixture of NaOH solution-water glass, and a mixture of KOH solution-water glass. Geopolymer with NaOH solution as activator had a compressive strength which was higher compared to geopolymer with KOH solution as an activator. However, geopolymer with NaOH solution-water glass as activator had a compressive strength which was lower compared to geopolymer with KOH solution-water glass as activator either at room temperature curing or at a curing temperature of 60 °C. The use of water glass with NaOH or KOH solution as activator could increase the compressive strength of geopolymer and yielded geopolymer having more dense and more homogeneous microstructure seen from SEM images. XRD patterns revealed the presence of sodium aluminosilicate hydrate in geopolymer with NaOH solution and NaOH solution-water glass as activators, and potassium aluminosilicate hydrate in geopolymer with KOH solution and KOH solution-water glass as activators. Furthermore, FTIR spectra indicated asymmetrical vibration of Si(Al)-O at around 1008 cm-1 related to geopolymer product.

scholarly journals Assessment of the Rheological and Mechanical Properties of Geopolymer Concrete Comprising Fly Ash and Fluid Catalytic Cracking Residue as Aluminosilicate Precursor

2021 ◽  
Vol 11 (7) ◽  
pp. 3032
Author(s):  
Tuan Anh Le ◽  
Sinh Hoang Le ◽  
Thuy Ninh Nguyen ◽  
Khoa Tan Nguyen
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Fly Ash ◽  
Flexural Strength ◽  
Catalytic Cracking ◽  
Fluid Catalytic Cracking ◽  
High Alumina ◽  
Geopolymer Concrete ◽  
Sem Images

The use of fluid catalytic cracking (FCC) by-products as aluminosilicate precursors in geopolymer binders has attracted significant interest from researchers in recent years owing to their high alumina and silica contents. Introduced in this study is the use of geopolymer concrete comprising FCC residue combined with fly ash as the requisite source of aluminosilicate. Fly ash was replaced with various FCC residue contents ranging from 0–100% by mass of binder. Results from standard testing methods showed that geopolymer concrete rheological properties such as yield stress and plastic viscosity as well as mechanical properties including compressive strength, flexural strength, and elastic modulus were affected significantly by the FCC residue content. With alkali liquid to geopolymer solid ratios (AL:GS) of 0.4 and 0.5, a reduction in compressive and flexural strength was observed in the case of geopolymer concrete with increasing FCC residue content. On the contrary, geopolymer concrete with increasing FCC residue content exhibited improved strength with an AL:GS ratio of 0.65. Relationships enabling estimation of geopolymer elastic modulus based on compressive strength were investigated. Scanning electron microscope (SEM) images and X-ray diffraction (XRD) patterns revealed that the final product from the geopolymerization process consisting of FCC residue was similar to fly ash-based geopolymer concrete. These observations highlight the potential of FCC residue as an aluminosilicate source for geopolymer products.

scholarly journals Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

2019 ◽  
Vol 8 (2S8) ◽  
pp. 883-887
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Geopolymer Concrete ◽  
Sem Images ◽  
Before And After ◽  
Alkaline Conditions ◽  
Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

scholarly journals Properties of Ambient-Cured Normal and Heavyweight Geopolymer Concrete Exposed to High Temperatures

Materials ◽  
2019 ◽  
Vol 12 (5) ◽  
pp. 740 ◽  
Author(s):  
Farhad Aslani ◽  
Zohaib Asif
Keyword(s):  
Mass Loss ◽  
High Temperatures ◽  
Offshore Structures ◽  
Normal Weight ◽  
Geopolymer Concrete ◽  
Coarse Aggregates ◽  
Residual Properties ◽  
New Type ◽  
Heavyweight Concrete ◽  
Underwater Structures

Ambient-cured heavyweight geopolymer concrete (HWGC) is a new type of concrete that combines the benefits of both heavyweight concrete (HWC) and geopolymer concrete (GC). HWGC provides proper protection from the sources that emit harmful radiations in medical and nuclear industries. Furthermore, HWGC may also be used in offshore structures for pipeline ballasting and similar underwater structures. In this study, heavyweight aggregates (magnetite) have been used and replaced by normal-weight coarse aggregates in GC at volume ratios of 50, 75, and 100% to attain heavyweight classification according to British standards. This study investigates the impacts of high temperatures on standard ambient-cured geopolymer concrete and ambient-cured HWGC through its residual properties regarding compressive and tensile strengths, mass loss, spalling intensity, and flexural strength. The residual properties were examined by heating 100 × 200 mm cylinder specimens to 100, 300, 600, and 900 °C. The results indicated that the maximum compressive strengths of 40.1 and 39.0 MPa were achieved by HWGC at 300 and 100 °C, respectively. The overall result shows that the strength of HWGC increases by increasing magnetite aggregate proportion, while the mass loss, intensity of spalling, and loss of strengths is proportional to temperature after a certain point. Minor spalling with holes and cracking was observed only at 900 °C in HWGC.

scholarly journals Characterization of Slag Reprocessing Tailings-Based Geopolymers in Marine Environment

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 832 ◽  
Author(s):  
Jie Wu ◽  
Jing Li ◽  
Feng Rao ◽  
Wanzhong Yin
Keyword(s):  
Compressive Strength ◽  
Marine Environment ◽  
Copper Slag ◽  
X Ray Diffraction ◽  
Strength Measurement ◽  
X Ray ◽  
Sodium Aluminosilicate ◽  
Marine Concrete ◽  
Sodium Aluminosilicate Hydrate

In this study, copper slag reprocessing tailings (CSRT) were synthesized into geopolymers with 40%, 50% and 60% metakaolin. The evolution of compressive strength and microstructures of CSRT-based geopolymers in a marine environment was investigated. Except for compressive strength measurement, the characterizations of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) were included. It was found that marine conditions changed the Si/Al ratio in the sodium-aluminosilicate-hydrate (N-A-S-H) gel backbone, promoted the geopolymerization process, led to more Q4(3Al), Q4(2Al) and Q4(1Al) gel formation and a higher compressive strength of the geopolymers. This provided a basis for the preparation of CSRT-based geopolymers into marine concrete.

scholarly journals Effect of Fiber on Residual Strength and High Temperature Burst Performance of Ultra High Performance Concrete

2021 ◽  
pp. 224-231
Author(s):  
Huijie Shang, Qianqian Peng
Keyword(s):  
Compressive Strength ◽  
High Temperature ◽  
Mass Loss ◽  
Ultrasonic Wave ◽  
Wave Velocity ◽  
Residual Strength ◽  
High Performance ◽  
High Performance Concrete ◽  
Ultra High Performance Concrete ◽  
Burst Performance

In this paper, the effects of fiber on the residual strength and high temperature burst performance of ultra-high performance concrete are studied. This paper analyzes the performance change law of concrete after high temperature from three aspects: mass loss, ultrasonic wave velocity and compressive strength. The results show that with the increase of heating temperature, the mass loss increases and the ultrasonic wave velocity decreases. The compressive strength of concrete increases gradually before 300 ℃ and decreases gradually after 400 ℃. Mixing PVA fiber and steel fiber can not only improve the burst resistance of ultra-high performance concrete at high temperature, but also have high residual strength. This paper discusses the high temperature burst mechanism of ultra-high performance concrete, which is caused by the change of steam pressure and microstructure.

scholarly journals Influence of calcium and alumina-based pozzolanas on the strength properties of low calcium fly ash geopolymer concrete

2021 ◽  
Vol 309 ◽  
pp. 01104
Author(s):  
K Saiteja Chary ◽  
S Shrihari ◽  
V Siva Prasad Raju ◽  
V Srinivasa Reddy
Keyword(s):  
Fly Ash ◽  
Strength Properties ◽  
Main Reaction ◽  
Geopolymer Concrete ◽  
Main Reaction Product ◽  
Strength Performance ◽  
Sodium Aluminosilicate ◽  
Granulated Blast Furnace Slag ◽  
Calcium Aluminosilicate ◽  
Sodium Aluminosilicate Hydrate

This work presents the effect of Ground granulated blast furnace slag (GGBS), fly ash (FA) and metakaolin (MK) on the strength properties of geopolymer concrete (GPC). Geopolymer concrete made with FA produces calcium aluminosilicate hydrate (C-A-S-H) product due to presence of alumina and sodium aluminosilicate hydrate (N-A-S-H) gel as main reaction product of polymerization. Geopolymer concrete made with FA and GGBS, calcium silicate hydrate (C-S-H) also gets produced additionally with calcium aluminosilicate hydrate (C-A-S-H) gel and sodium aluminosilicate hydrate (N-A-S-H) gel due to presence of high content of CaO in GGBS. This additional product imparts more strength performance in GPC. In geopolymer concrete made with FA and MK, the more amount of calcium aluminosilicate hydrate (C-A-S-H) is produced due to presence of high amount of alumina in metakaolin along with sodium aluminosilicate hydrates (N-A-S-H) giving more strength to GPC. Metakaolin is recommended to be used for the development of GPC because it has high amount of alumina.

scholarly journals Residual Compressive Strength of Recycled Aggregate Concretes after High Temperature Exposure

Materials ◽  
2020 ◽  
Vol 13 (8) ◽  
pp. 1981 ◽  
Author(s):  
Francisco B. Varona ◽  
Francisco Baeza-Brotons ◽  
Antonio J. Tenza-Abril ◽  
F. Javier Baeza ◽  
Luis Bañón
Keyword(s):  
Compressive Strength ◽  
Construction Industry ◽  
Residual Strength ◽  
Raw Materials ◽  
Environmental Benefits ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Residual Properties ◽  
Negative Effect ◽  
Temperature Exposure

Sustainability requirements are gaining importance in the construction industry, which needs to take specific measures in the design and construction of concrete structures. The use of recycled aggregates in concrete may be of special interest. Recycling a construction waste will close the life cycle of the original materials (e.g., concrete). Thus, environmental benefits would come from the lower waste generation, and from a lower necessity of raw materials for new structures. The current Spanish code for structural concrete considers the use of recycled aggregates in replacement rates up to 20% by aggregate mass, assimilating their properties with those of concretes without aggregate replacement. Higher substitution percentages would require further testing. In this work, substitution of coarse aggregate for recycled aggregates (with replacement percentages of 25%, 50% and 100%) has been studied, and the concrete’s residual properties after exposure to high temperatures (between 350 °C and 850 °C) have been assessed. Compressive strength and capillary water absorption tests were made after heating, and the experiments showed higher residual strength in concretes with the greatest content of recycled aggregates. However, a statistical analysis made with additional data available in the literature seemed to predict otherwise, and the recycled aggregate replacement would have a negative effect on the residual strength.

scholarly journals Effects of heating durations on normal concrete residual properties: compressive strength and mass loss

2017 ◽  
Vol 271 ◽  
pp. 012013 ◽  
Author(s):  
Fadzli Mohamed Nazri ◽  
Shahiron Shahidan ◽  
Nur Khaida Baharuddin ◽  
Salmia Beddu ◽  
Badorul Hisyam Abu Bakar
Keyword(s):  
Compressive Strength ◽  
Mass Loss ◽  
Normal Concrete ◽  
Residual Properties
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