scholarly journals Microstructural and Mechanical Properties of Alkali Activated Materials from Two Types of Blast Furnace Slags

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2089 ◽  
Author(s):  
Jun Xing ◽  
Yingliang Zhao ◽  
Jingping Qiu ◽  
Xiaogang Sun
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Blast Furnace ◽  
Thermal Stabilization ◽  
Hydration Process ◽  
Reaction Products ◽  
Basic Oxide ◽  
X Ray ◽  
Physical And Chemical ◽  
Alkali Activated

This paper investigated the effect of blast furnace slags (BFS) characteristics on the properties achievement after being alkali activated. The physical and chemical characteristics of BFS were determined by X-ray fluorescence (XRF), X-ray Diffraction (XRD) and laser granulometry. Multi-technical characterizations using calorimetry, XRD, Fourier Transform Infrared Spectroscopy (FTIR), Thermogravimetry (TG-DTG), scanning electron microscope (SEM), nitrogen sorption and uniaxial compressive strength (UCS) were applied to give an in-depth understanding of the relationship between the reaction products, microstructure and BFS characteristics. The test results show that the microstructure and mechanical properties of alkali activated blast furnace slags (BFS) highly depend on the characteristics of BFS. Although the higher content of basic oxide could accelerate the hydration process and result in higher mechanical properties, a poor thermal stabilization was observed. On the other hand, with a higher content of Fe, the hydration process in alkali activated BFS2 lasts for a longer time, contributing to a delayed compressive strength achievement.

scholarly journals Mechanical properties and permeability of red mud-blast furnace slag-based geopolymer concrete

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Xiangzhou Liang ◽  
Yongsheng Ji
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Blast Furnace ◽  
Red Mud ◽  
Blast Furnace Slag ◽  
Construction Materials ◽  
Geopolymer Concrete ◽  
Reaction Products ◽  
Alumina Production ◽  
Furnace Slag

AbstractRed mud, a by-product of alumina production, has a great impact on the environment due to its high alkalinity. In this paper, two-part geopolymer mortar was synthesized by combining red mud and blast furnace slag (BFS) to obtain optimized compressive strength and flexural strength for construction materials. Geopolymer concrete was prepared with the cementitious material in the concrete replaced by geopolymer mortar. Mechanical properties, permeability and microscopic properties of geopolymer concrete were measured. The results showed that the compressive strength grade of concrete prepared with geopolymer concrete can reach 54.43 MPa indicating that the geopolymer concrete can be used as materials for load-bearing members in structures. Due to lower total porosity and better pore structure, the permeability resistance of geopolymer concrete was significantly better than ordinary concrete. Microscopic analysis indicated that a large amount of aluminosilicate reaction products was generated in a geopolymer by the reaction of OH− with the aluminosilicate components in red mud and BFS in a strongly alkaline environment. The surface [SiO4]4− and [AlO4]4− tetrahedrons form chemical bonds through dehydroxylation, which is the direct reason for their high strength and determines their excellent physical and chemical properties.

scholarly journals Physical and Chemical Relationships in Accelerated Carbonation Conditions of Alkali-Activated Cement Based on Type of Binder and Alkali Activator

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 671
Author(s):  
Yuto Yamazaki ◽  
Jihoon Kim ◽  
Keisuke Kadoya ◽  
Yukio Hama
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Accelerated Carbonation ◽  
Chemical Changes ◽  
Physical Changes ◽  
Physical And Chemical ◽  
Furnace Slag ◽  
Alkali Activated

Alkali-activated cements prepared from aluminosilicate powders, such as blast furnace slag and fly ash, are rapidly attracting attention as alternatives to cement because they can significantly reduce CO2 emissions compared to conventional cement concrete. In this study, we investigated the relationship between the physical and chemical changes by accelerated carbonation conditions of alkali-activated cements. Alkali-activated cements were prepared from binders composed of blast furnace slag and fly ash as well as alkali activators sodium silicate and sodium hydroxide. Physical changes were analyzed from compressive strength, pH, and neutralization depth, and chemical changes were analyzed from XRD, TG-DTG, and 29Si MAS NMR. The C–(N)–A–S–H structure is noted to change via carbonation, and the compressive strength is observed to decrease. However, in the case of Na-rich specimens, the compressive strength does not decrease by accelerated carbonation. This work is expected to contribute to the field of alkali-activated cements in the future.

Microstructure, strength, and reaction products of ground granulated blast-furnace slag activated by highly concentrated NaOH solution

1994 ◽  
Vol 9 (1) ◽  
pp. 188-197 ◽  
Author(s):  
Paul J. Schilling ◽  
Amitava Roy ◽  
H.C. Eaton ◽  
Philip G. Malone ◽  
Newell W. Brabston
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Reaction Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulated Blast Furnace Slag ◽  
Naoh Solution ◽  
Concentrated Solution ◽  
Furnace Slag

Ground granulated blast-furnace slag was reacted in 5 M (pH 14.7) and 1.5 M (pH 14.2) NaOH solutions at a water/slag ratio of ∼0.4, and characterized by unconfined compressive strength testing, scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction. The reacted material consisted of a dense layered matrix interspersed with unreacted glass particles and regions of reaction products with higher porosity. CSH(I) and (C, M)4AH13 were identified by x-ray diffraction. The C-S-H (calcium silicate hydrate) phase is proposed to consist mainly of structurally imperfect layers of tobermorite, interleaved with layers of (C, M)4AH13. Other cations, most significantly Na+, are incorporated into the structure. Use of the highly concentrated solution (5 M) produced a higher degree of reaction and, consequently, higher compressive strength (38 MPa after 28 days for 5 M solution vs 21 MPa for 1.5 M).

scholarly journals The Effect of Activators on the Mechanical Properties and Microstructure of Alkali-Activated Nickel Slag

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Liwei Xu ◽  
Xuefang Wang ◽  
Can Guan ◽  
Wenda Wu ◽  
Lingling Zhang
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Energy Dispersive Spectrometer ◽  
Engineering Application ◽  
X Ray ◽  
Different Types ◽  
Lower Porosity ◽  
Infrared Spectrometer ◽  
Mercury Analyzer ◽  
Alkali Activated

In order to mitigate problems associated with environmental pollution, alkali-activated nickel slags (AANSs) may be used as an alternative to cementitious material. However, the understanding of their mechanical properties and microstructure is currently very limited. This paper therefore explores the influence of different types and contents of three solid alkali activators, Na2SiO3, NaOH, and Na2SiO3/Na2CO3, on the compressive strength of one-part AANS. Their microstructure, hydration components, and pore structure are analyzed by means of a scanning electron microscope, an energy-dispersive spectrometer, an X-ray diffractometer, an infrared spectrometer, and a mercury analyzer. The results show that the AANS with an Na2SiO3/Na2CO3 activator has a denser microstructure, lower porosity, and a smaller pore size when compared with the AANS with the Na2SiO3 or NaOH activators. Consequently, the compressive strength of the Na2SiO3/Na2CO3 sample reached a higher compressive strength (96 MPa) than that activated by Na2SiO3 or NaOH. This strength is optimal as well as more economical as Na2O, which increased from 0.107 mol to 0.123 mol, contributes little to compressive strength. The final part of the article discusses an optimal design for the engineering application of one-part AANS.

scholarly journals Alkali-Activated Binders Based on Tungsten Mining Waste and Electric-Arc-Furnace Slag: Compressive Strength and Microstructure Properties

CivilEng ◽  
2020 ◽  
Vol 1 (2) ◽  
pp. 154-180
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Compressive Strength ◽  
Electric Arc ◽  
Mining Waste ◽  
Arc Furnace ◽  
Reaction Products ◽  
X Ray ◽  
Eaf Slag ◽  
Electric Arc Furnace Slag ◽  
Furnace Slag ◽  
Alkali Activated

The valorization and reusing of mining waste has been widely studied in recent years. Research has demonstrated that there is great potential for reusing mining waste for construction applications. This work experimentally investigated the strength development, pore structure, and microstructure of a binary alkali-activated binder. This is based on tungsten mining waste mud (TMWM) and electric-arc-furnace slag (EAF-Slag) using different proportions of TMWM (10, 20, 30, 40, and 50 vt.%). The precursors were activated using sodium silicate (Na2SiO3) and potassium hydroxide (KOH 8M) as alkaline activator solution with solid:liquid weight ratio = 3. Pastes were used to assess the compressive strength of the blended binder and their microstructure. The reaction products were characterized by X-ray diffraction (XRD), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS), and Fourier transform infra-red (FT-IR) spectroscopy, while the porosity and the pores size properties were examined by mercury intrusion porosimetry (MIP). The results show that the partial replacement of TMWM with EAF-Slag exhibited better mechanical properties than the 100TM-AAB. A maximum strength value of 20.1 MPa was obtained in the binary-AAB sample prepared with 50 vt.% TMWM and EAF-Slag. The pastes that contained a higher dosage of EAF-Slag became more compact with lower porosity and finer pore-size distribution. In addition, the results obtained by SEM-EDS confirmed the formation of different types of reaction products in the 100TM-AAB, 100FS-AAB, and the binary-AABs mixtures such as N-A-S-H, C-A-S-H and (N, C)-A-S-H gels frameworks in the system as the major elements detected are Si, Al, Ca, and Na.

Properties of Environmental Friendly Concrete Containing Recycled Coarse Aggregate and Fly Ash

2013 ◽  
Vol 368-370 ◽  
pp. 957-962
Author(s):  
Xiao Shuang Shi ◽  
Qing Yuan Wand ◽  
Lang Li ◽  
Tao Long
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Compressive Strength ◽  
Coarse Aggregate ◽  
Recycled Concrete ◽  
Reaction Products ◽  
X Ray ◽  
Transition Zones ◽  
Environmental Friendly ◽  
Scanning Electron

Six mixtures with different ratios (0%, 50% and 100%) were designed to investigate the compressive strength, elastic modulus and Poissons ratio of geopolymeric recycled concrete (GRC). The mechanical properties and failure mechanism of recycled concrete (RAC) and GRC were tested and discussed by scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). The results show that, GRC concretes are stronger than RAC concretes due to different reaction products and better microstructure in interfacial transition zones (ITZs). The EDX results show that the higher compressive strength with higher Si/Al ratio.

scholarly journals The Effect of Different Types of Internal Curing Liquid on the Properties of Alkali-Activated Slag (AAS) Mortar

2021 ◽  
Vol 13 (4) ◽  
pp. 2407
Author(s):  
Guang-Zhu Zhang ◽  
Xiao-Yong Wang ◽  
Tae-Wan Kim ◽  
Jong-Yeon Lim ◽  
Yi Han
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Deionized Water ◽  
Internal Curing ◽  
Control Group ◽  
Alkali Activated Slag ◽  
Different Types ◽  
Naoh Solution ◽  
Activated Slag ◽  
Alkali Activated

This study shows the effect of different types of internal curing liquid on the properties of alkali-activated slag (AAS) mortar. NaOH solution and deionized water were used as the liquid internal curing agents and zeolite sand was the internal curing agent that replaced the standard sand at 15% and 30%, respectively. Experiments on the mechanical properties, hydration kinetics, autogenous shrinkage (AS), internal temperature, internal relative humidity, surface electrical resistivity, ultrasonic pulse velocity (UPV), and setting time were performed. The conclusions are as follows: (1) the setting times of AAS mortars with internal curing by water were longer than those of internal curing by NaOH solution. (2) NaOH solution more effectively reduces the AS of AAS mortars than water when used as an internal curing liquid. (3) The cumulative heat of the AAS mortar when using water for internal curing is substantially reduced compared to the control group. (4) For the AAS mortars with NaOH solution as an internal curing liquid, compared with the control specimen, the compressive strength results are increased. However, a decrease in compressive strength values occurs when water is used as an internal curing liquid in the AAS mortar. (5) The UPV decreases as the content of zeolite sand that replaces the standard sand increases. (6) When internal curing is carried out with water as the internal curing liquid, the surface resistivity values of the AAS mortar are higher than when the alkali solution is used as the internal curing liquid. To sum up, both NaOH and deionized water are effective as internal curing liquids, but the NaOH solution shows a better performance in terms of reducing shrinkage and improving mechanical properties than deionized water.

scholarly journals Enhancing Density-Based Mining Waste Alkali-Activated Foamed Materials Incorporating Expanded Cork

CivilEng ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 523-540
Author(s):  
Imed Beghoura ◽  
Joao Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Pore Size ◽  
Physical And Mechanical Properties ◽  
Critical Parameters ◽  
Porous Structures ◽  
Foaming Agent ◽  
Al Powder ◽  
Highly Porous ◽  
Alkali Activated

This study focuses on the development of an alkali-activated lightweight foamed material (AA-LFM) with enhanced density. Several mixes of tungsten waste mud (TWM), grounded waste glass (WG), and metakaolin (MK) were produced. Al powder as a foaming agent was added, varying from 0.009 w.% to 0.05 w.% of precursor weight. Expanded granulated cork (EGC) particles were incorporated (10% to 40% of the total volume of precursors). The physical and mechanical properties of the foamed materials obtained, the effects of the amount of the foaming agent and the percentage of cork particles added varying from 10 vol.% to 40% are presented and discussed. Highly porous structures were obtained, Pore size and cork particles distribution are critical parameters in determining the density and strength of the foams. The compressive strength results with different densities of AA-LFM obtained by modifying the foaming agent and cork particles are also presented and discussed. Mechanical properties of the cured structure are adequate for lightweight prefabricated building elements and components.

scholarly journals Features of the hydration process of the modified blended cement for fiber cement panels

2018 ◽  
Vol 170 ◽  
pp. 03030 ◽  
Author(s):  
Rustem Mukhametrakhimov ◽  
Liliya Lukmanova
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Blended Cement ◽  
Physical And Mechanical Properties ◽  
Hydration Process ◽  
Cement Matrix ◽  
X Ray Diffraction ◽  
Structure Form ◽  
Silicate Phase ◽  
X Ray

The paper studies features of the hydration process of the modified blended cement for fiber cement panels (FCP) using differential thermal analysis, X-ray diffraction analysis, electron microscopy and infrared spectroscopy. It is found that deeper hydration process in silicate phase, denser and finer crystalline structure form in fiber cement matrix based on the modified blended cement. Generalization of this result to the case of fiber cement panels makes it possible to achieve formation of a denser and homogeneous structure with increased physical and mechanical properties.

Microstructural Features and Mechanical Properties of Autoclaved Saline Soil Brick: Part II: Mechanical Properties

2012 ◽  
Vol 510 ◽  
pp. 655-659
Author(s):  
Lie Qu ◽  
Jiu Jun Yang ◽  
Shou Xi Chai ◽  
Lei Guo ◽  
Su Li
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Hydrothermal Reaction ◽  
Saline Soil ◽  
Reaction Products ◽  
Quartz Powder ◽  
Water Binding ◽  
Binding Ratio ◽  
Compressive And Flexural Strengths ◽  
Optimal Material

The effects of different components, autoclaving temperature and time on the mechanical properties of saline soil bricks were investigated. The autoclaved curing schedule is optimized at autoclaving time of 3h and autoclaving temperature of 175. The optimal material formula consists of water-binding ratio 0.2, CaO 15%, finely grinded quartz powder 20 % and sand 20%, under which the compressive and flexural strengths of saline soil bricks reaches 31.9 Mpa and 7.8Mpa, respectively. Reducing water-binding ratio will effectively promote density, while increasing the amount of CaO will enhance the hydrothermal reaction products, density and the mechanical strength. In addition, adding finely grinded quartz powder and sand will further increase the hydrothermal reaction products and restrict volume shrinkage. Furthermore, elevating autoclaving temperature and extending autoclaving time are favorable to increase density and to improve mechanical properties. But autoclaving time exceeds 3h, the compressive strength will be reduced.

Sign in / Sign up

Export Citation Format

Share Document