scholarly journals Durability Analysis of Sludge Solidified with Soda Residue Subjected to Dry-Wet and Freeze-Thaw Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Jun He ◽  
Lei Zhang ◽  
Chi Zhang
Keyword(s):  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Durability Test ◽  
Cycle Number ◽  
Freeze Thaw ◽  
Industrial Solid Waste ◽  
Filling Materials ◽  
Granulated Blast Furnace Slag ◽  
Durability Analysis ◽  
Furnace Slag

Soda residue (SR), ground-granulated blast-furnace slag (GGBS), and quicklime (QL) were employed for solidifying sewage sludge, which is a technique for sustainable development by transforming industrial solid waste and sludge into engineering fill material such as backfill material in mine or abandoned caverns. The durability of solidified sludge against dry-wet and freeze-thaw cycles was investigated by unconfined compressive strength (UCS), X-ray diffraction, scanning electron microscopy, and nuclear magnetic resonance tests. The results demonstrated that the SR-GGBS-QL solidified sludge had good dry-wet and freeze-thaw durability. In general, UCS increased at first, but then it decreased to some degree with the increase in dry-wet and freeze-thaw cycles. The cycle number for peak UCS depended on the durability test types and SR content. The UCS values after seven dry-wet cycles or ten freeze-thaw cycles were higher than the initial values before cycles. The main products detected in SR-GGBS-QL solidified sludge were ettringite, hydroaluminite, and calcium silicate hydrate (C-S-H). In addition, some pollutants such as copper, arsenic, and chromium were stabilized. The weakening effect on the microstructure of the solidified sludge occurred after dry-wet or freeze-thaw cycles. However, the hydration reaction continued with the increase of dry-wet and freeze-thaw cycles, leading to an increase in the amount of hydration products (especially C-S-H) and compact microstructure. These contributed to high UCS values and good dry-wet and freeze-thaw durability. The strength and failure strain of solidified sludge still met the requirement of filling materials after dry-wet or freeze-thaw cycles.

scholarly journals Synergistic Excitation Mechanism of CaO-SiO2-Al2O3-SO3 Quaternary Active Cementitious System

2021 ◽  
Vol 8 ◽  
Author(s):  
Fusheng Niu ◽  
Yukun An ◽  
Jinxia Zhang ◽  
Wen Chen ◽  
Shengtao He
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Cementitious Materials ◽  
Test Block ◽  
Hydration Reaction ◽  
Alkaline Environment ◽  
Granulated Blast Furnace Slag ◽  
Cementitious System ◽  
Furnace Slag

In this study, the influence of steel slag (SS) content on the strength of the cementitious materials was investigated. The quaternary active cementitious material (CaO-SiO2-Al2O3-SO3) was prepared using various proportions of steel slag (SS), granulated blast furnace slag (BFS), and desulfurized gypsum (DG). The mechanism of synergistic excitation hydration of the cementitious materials was examined using various techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectrometry (FTIR). The strength of the mortar test block was initially increased and decreased later with the increase of the SS content. Mortar test block with 20% steel slag, 65% granulated blast furnace slag, and 15% desulfurized gypsum with 0.35 water-binder ratio showed the highest compressive strength of 57.3 MPa on 28 days. The free calcium oxide (f-CaO) in the SS reacted with water and produced calcium hydroxide (Ca(OH)2) which created an alkaline environment. Under the alkaline environment, the alkali-activated reaction occurred with BFS. In the early stage of hydration reaction, calcium silicate hydrate (C-S-H) gel and fibrous hydration product ettringite (AFt) crystals were formed, which provided early strength to the cementitious materials. As the hydration reaction progressed, the interlocked growth of C-S-H gel and AFt crystals continued and promoted the increase of the strength of the cementitious system.

scholarly journals Utilization of Calcium Carbide Residue Using Granulated Blast Furnace Slag

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3511 ◽  
Author(s):  
Joonho Seo ◽  
Solmoi Park ◽  
Hyun No Yoon ◽  
Jeong Gook Jang ◽  
Seon Hyeok Kim ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Calcium Carbide ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
X Ray Diffraction ◽  
Granulated Blast Furnace Slag ◽  
Calcium Carbide Residue ◽  
Angle Spinning ◽  
Furnace Slag

The solidification and stabilization of calcium carbide residue (CCR) using granulated blast furnace slag was investigated in this study. CCR binding in hydrated slag was explored by X-ray diffraction, 29Si and 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy, and thermodynamic calculations. Mercury intrusion porosimetry and and compressive strength tests assessed the microstructure and mechanical properties of the mixtures of slag and CCR. C-A-S-H gel, ettringite, hemicarbonate, and hydrotalcite were identified as the main phases in the mixture of slag and CCR. The maximum CCR uptake by slag and the highest volume of precipitated solid phases were reached when CCR loading in slag is 7.5% by mass of slag, according to the thermodynamic prediction. This feature is also experimentally observed in the microstructure, which showed an increase in the pore volume at higher CCR loading.

Utilization of Ground Granulated Blast-Furnace Slag Seed Crystal in Eco-Cement

2011 ◽  
Vol 250-253 ◽  
pp. 870-874
Author(s):  
Hong Mei Ai ◽  
Jing Wei ◽  
Jun Ying Bai ◽  
Pu Guang Lu
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Sintering Temperature ◽  
Seed Crystal ◽  
Cement Clinker ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
Granulated Blast Furnace Slag ◽  
Lower Temperature ◽  
Furnace Slag

Eco-cement produced from waste concrete was proved to be feasible in early research. The seed crystal of ground granulated blast furnace slag (GGBS) was utilized in this research to lower the sintering temperature of eco-cement clinker. The mineral compositions of clinker with GGBS seed crystal was analyzed by X-ray diffraction (XRD), and the mechanical properties of eco-cement with GGBS seed crystal was also tested. Four main cement minerals were all observed in eco-cement clinker and the compressive strength of the eco-cement pastes can approach to about 66 MPa at 28 curing days. The results showed that GGBS seed crystal was favourable for the formation of cement minerals at a lower temperature. It can help reduce by about 50~100°C for the sintering process of cement clinker. Content of GGBS seed crystal should better be in the rage of 5%~8%, and the suitable sintering temperature should be 1350°C.

Influence of SiO2/Al2O3 Content on Structure and Hydration Activity of Granulated Blast Furnace Slag

2014 ◽  
Vol 633 ◽  
pp. 240-244 ◽  
Author(s):  
Su Ping Cui ◽  
Ling Ling Liu ◽  
Jing Chen ◽  
Ya Li Wang ◽  
Jian Feng Wang ◽  
...  
Keyword(s):  
Absorption Spectrum ◽  
Blast Furnace ◽  
Mechanical Testing ◽  
Infrared Radiation ◽  
Blast Furnace Slag ◽  
Actual Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

Granulated blast furnace slag (GBFS) is a by-product of manufacturing iron. Samples of GBFS with different ratio of SiO2/Al2O3 were prepared by simulating the actual process of GBFS in laboratory. This study investigated the influence of SiO2/Al2O3 content on structure and hydration activity of GBFS which were characterized by X-ray fluorescence (XRF), powder X-ray diffraction (XRD), infrared radiation (IR) and mechanical testing. It is found that the vitreous content of each sample is above 97% and the hydration activity indexes of 7d and 28d of samples significantly decrease with the increase of SiO2/Al2O3 ratio. The IR characteristic absorption spectrum shows that the silicates mainly exist in [SiO4]-tetrahedra and the aluminum atoms are in different coordination states and the bonding strengths rise with the increase of SiO2/Al2O3 ratio.

Kinetics of Hydration and Hardening Processes in Clinkerless Slag-Alkaline Binder Materials

2015 ◽  
Vol 725-726 ◽  
pp. 499-504 ◽  
Author(s):  
Tatyana Petrova ◽  
Valentina Prokofieva
Keyword(s):  
Portland Cement ◽  
Early Stage ◽  
Concrete Strength ◽  
Heat Emission ◽  
Hydration Reaction ◽  
Active Centers ◽  
Granulated Blast Furnace Slag ◽  
Alkaline Component ◽  
Kinetics Of ◽  
Furnace Slag

<p>The purpose of the present work is to research the process of hardening clinkerless slag-alkaline binder materials during the early stage of interaction between the ground granulated blast-furnace slag and the alkaline component by the thermokinetic method. The amount of heat emitted during the interaction between slag and alkaline component, and the influence of the duration of slag pre-hydration period upon this process have been assessed. These values were compared to similar values for binder materials based on portland cement. It was shown that ageing has significantly larger influence on heat emission during hydration of portland cement and on concrete strength.<br />We have elaborated in more detail the mechanism of hydration reaction of slag-alkaline binder materials starting at the level of active centers on the surface in accordance with the process of self-decelerating forming of crystallization centers. As slag grains are covered with a layer of hydrates, kinetics of hydration till the end of reaction is regulated by the process of diffusion that depends on the degree of structural irregularity.</p>

scholarly journals Mechanical and Microstructural Properties of Copper Slag Based Blended Geopolymer Concrete

2021 ◽  
Author(s):  
Vijayasarathy RATHANASALAM ◽  
Jayabalan PERUMALSAMI ◽  
Karthikeyan JAYAKUMAR
Keyword(s):  
Fly Ash ◽  
Mechanical Characterization ◽  
Copper Slag ◽  
Fine Aggregate ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Granulated Blast Furnace Slag ◽  
Mechanical And Microstructural Properties ◽  
Furnace Slag

This work presents a novel way to examine the characteristics of fly ash, copper slag (CPS) along with the addition of Ultrafine Ground Granulated Blast Furnace Slag (UFGGBFS) based Geopolymer Concrete (GPC) for various molarities (10M, 12M and 14M). In GPC, fly ash was replaced with UFGGBFS (5 %, 10 % and 15 %) and copper slag was used as fine aggregate. Mechanical Characterization such as split tensile, flexural strength, workability and water absorption were conducted . GPC characterization and microstructural behaviour was studied  by examining X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). From experimental results this study concludes that with a rise in molarity of GPC, along with incorporation of UFGGBFS, improved the performance, densification and strength of GPC.

Sign in / Sign up

Export Citation Format

Share Document