scholarly journals Multi-scale analysis on soil improved by alkali activated binders

2019 ◽  
Vol 92 ◽  
pp. 11003 ◽  
Author(s):  
Enza Vitale ◽  
Giacomo Russo ◽  
Dimitri Deneele
Keyword(s):  
Engineering Properties ◽  
Test Results ◽  
Compression Tests ◽  
X Ray Diffraction ◽  
Multi Scale ◽  
Time Test ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Initial Reactivity ◽  
Mineralogical Phases

In the present paper, the use of alkali activated binders to improve engineering properties of clayey soils is presented as an alternative to traditional binders such as lime or cement. An alkali-activated fly ash and its chemo-physical evolution has been monitored at increasing curing times by means of X-Ray Diffraction and Scanning Electron Microscopy. Alkali-activated binder has been mixed with soil for evaluating the improvement of its mechanical behaviour. One-dimensional compression tests on treated samples have been performed with particular reference to effects induced by binder content and curing time. Test results showed a high initial reactivity of the alkali activated systems promoting formation of new mineralogical phases responsible of the mechanical improvement of the treated soil.

scholarly journals Effect of CaSO4 Incorporation on Pore Structure and Drying Shrinkage of Alkali-Activated Binders

Materials ◽  
2019 ◽  
Vol 12 (10) ◽  
pp. 1673 ◽  
Author(s):  
Hyeongmin Son ◽  
Sol Moi Park ◽  
Joon Ho Seo ◽  
Haeng Ki Lee
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Phase Changes ◽  
X Ray Diffraction ◽  
Activated Slag ◽  
Capillary Tension ◽  
Alkali Activated Binders ◽  
Internal Pore Structure ◽  
Alkali Activated

This present study investigates the effects of CaSO4 incorporation on the pore structure and drying shrinkage of alkali-activated slag and fly ash. The slag and fly ash were activated at a 5:5 ratio by weighing with a sodium silicate. Thereafter, 0%, 5%, 10%, and 15% of CaSO4 were incorporated to investigate the changes in phase formation and internal pore structure. X-Ray Diffraction (XRD), thermogravimetry (TG)/derivative thermogravimetry (DTG), mercury intrusion porosimetry (MIP), nuclear magnetic resonance (NMR), and drying shrinkage tests were carried out to find the correlation between the pore structure and drying shrinkage of the specimens. The results showed that CaSO4 incorporation increased the formation of thenardite, and these phase changes affected the pore structure of the activated fly ash and slag. The increase in the CaSO4 content increased the pore distribution in the mesopore. As a result, the capillary tension and drying shrinkage decreased.

Experimental Research on the Engineering Properties of Foam-Improved Red Clay Soil

2011 ◽  
Vol 261-263 ◽  
pp. 1831-1835
Author(s):  
Guo Gang Qiao ◽  
Da Jun Yuan ◽  
Bo Liu
Keyword(s):  
Experimental Research ◽  
Clay Soil ◽  
Soil Improvement ◽  
Engineering Properties ◽  
Screw Conveyor ◽  
Test Results ◽  
X Ray Diffraction ◽  
Shield Tunneling ◽  
Red Clay ◽  
Improvement Measures

Red clay soil is widely distributed in south China, the microstructure of red clay soil was studied applying scanning electron microscopy (SEM), and the X-ray diffraction analysis (XRD) test found that a large number of swelling inducing minerals, for example, montmorillonite, illite-montmorillonite or chlorite-smectite were contained in the red clay soil. Shield tunneling in this kind of stratum is prone to arising “cake” and “arch” phenomena and it prone to lead screw conveyor device unsmooth dumping, so soil improvement measures must be taken. Foam as the most advanced soil conditioner has been widely used in shield construction. Using self-developed foam agent, experimental research on foam conditioning red clay soil was carried out, test results show that foam can not only significantly reduce the soil shear strength, but also can greatly enhance the soil's compressibility and fluidity, which is significant for the smooth dumping and excavation face stability maintenance.

Durability of Alkali-Activated Fly Ash/Slag Concrete

2017 ◽  
Vol 904 ◽  
pp. 157-161 ◽  
Author(s):  
Mao Chieh Chi ◽  
Hsian Chen ◽  
Tsai Lung Weng ◽  
Ran Huang ◽  
Yih Chang Wang
Keyword(s):  
Fly Ash ◽  
Total Charge ◽  
Test Results ◽  
Mass Ratio ◽  
Modulus Ratio ◽  
Granulated Blast Furnace Slag ◽  
Alkali Activated Binders ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Better Than

This study investigated the durability of alkali-activated binders based on blends of fly ash (FA) and ground granulated blast furnace slag (GGBFS). Five fly ash-to-slag ratios of 100/0, 75/25, 50/50, 25/75, and 0/100 by mass were selected to produce alkali-activated fly ash/slag (AAFS) concrete. Sodium oxide (Na2O) concentrations of 6% and 8% of binder weight and activator modulus ratios (mass ratio of SiO2 to Na2O) of 0.8, 1.0, and 1.23 were used as alkaline activators. Test results show that the total charge passed of AAFS concrete is between 2500 and 4000 coulombs, higher than the comparable OPC concrete. However, AAFS concrete exposed to sulfate attack performed better than OPC concrete. Based on the results, 100% slag-based AAFS concrete with Na2O concentration of 8% and activator modulus ratio of 1.23 has the superior performances.

Fabrication and engineering properties of concretes based on geopolymers/alkali-activated binders - A review

2020 ◽  
Vol 258 ◽  
pp. 120896 ◽  
Author(s):  
Peng Zhang ◽  
Kexun Wang ◽  
Qingfu Li ◽  
Juan Wang ◽  
Yifeng Ling
Keyword(s):  
Engineering Properties ◽  
Alkali Activated Binders ◽  
Alkali Activated

scholarly journals Use of Iron Ore Overburden As a Precursor for the Synthesis of an Alkali-activated Binder

2020 ◽  
Author(s):  
Marina Filizzola Oliveira ◽  
Naim Sedira ◽  
Ana Cláudia Guimarães ◽  
Fernando Lameiras ◽  
João Castro-Gomes
Keyword(s):  
Iron Ore ◽  
Sodium Hydroxide Solution ◽  
Microstructural Characterization ◽  
Raw Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mining Companies ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Scanning Electron

The iron ore beneficiation process produces a large quantity of waste. Mining companies are looking for technologies that make it possible to dispose of their waste and transform it into raw material for the manufacture of products that can be applied in other areas, for example in the production of concrete, mortar, ceramics, blocks, and bricks. This study aimed at the feasibility of using a calcined iron ore overburden as a precursor of alkali-activated binders. For alkaline activation of the precursors, sodium hydroxide solution and sodium silicate were used in the atomic proportions Al / Na = 2 and Si / Al> 0,7. Mineralogical and microstructural characterization was carried out by X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). Tests of compressive strength were performed for the binders with 7, 14, 21 and 28 of curing days. The results of the analyses demonstrated that the properties of the alkali-activated binders produced with the overburden were similar to the binders obtained by precursors used traditionally. It was found, therefore, that the calcined iron ore overburden, can be considered a precursor for obtaining alkaline activated binders

scholarly journals Leaching of alkali-activated tungsten mining waste materials by electrical conductivity and DRX

2019 ◽  
Vol 274 ◽  
pp. 02002
Author(s):  
Ana Fernandes ◽  
Manuel Magrinho ◽  
João Castro-Gomes
Keyword(s):  
Electrical Conductivity ◽  
Portland Cement ◽  
Research Work ◽  
High Energy ◽  
Mining Waste ◽  
Ftir Analysis ◽  
Compression Tests ◽  
Chemical Leaching ◽  
Alkali Activated Binders ◽  
Alkali Activated

The production of Portland cement leads to high energy and natural resource consumption, as well as relevant emission of CO2 into the atmosphere. Thus, this research work intends to contribute to the study of Portland cement alternative alkali activated binders, which utilization can contribute to counteract to this status. Different samples of alkaline activated binders using different combinations of tungsten mining waste from Panasqueira Mines, milled glass and metakaolin were made. Compression tests were performed at 3, 7, 14 and 28 days of curing. For evaluating reactivity chemical leaching was measured. For such, conductivity tests were carried out simultaneously with pH measurement, SEM-BSE and ATR-FTIR analysis. Electrical conductivity tests enabled to preliminary identify the chemical leaching for different precursors. Additionally, by SEM-BSE it was possible to observed reacted and nonreacted particles, and the reactivity extend was confirmed by ATR-FTIR.

scholarly journals Effects of EAF-Slag on alkali-activation of tungsten mining waste: mechanical properties

2019 ◽  
Vol 274 ◽  
pp. 01003 ◽  
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Mechanical Properties ◽  
Sodium Silicate ◽  
Mining Waste ◽  
Alkali Activation ◽  
X Ray Diffraction ◽  
Eaf Slag ◽  
Electric Arc Furnace Slag ◽  
Solid Liquid ◽  
Alkali Activated Binders ◽  
Alkali Activated

The mechanical properties of alkali-activated binders based on blends of tungsten mining waste mud (TMWM) and electric arc furnace slag (EAF-S) were investigated. The synthesis of alkali-activated binders was conducted at 60°C for 24 h with different TMWM/EAF-Slag ratios (90:10, 80:20, 70:30, 60:40, and 50:50 vt.%). Using sodium hydroxide (SH) and sodium silicate (SS) solutions as alkaline activators with ratio solid/liquid 4 by unit of volume, and the sodium silicate to NaOH (SS:SH) ratio of 2:1. The X-ray Diffraction (XRD), mercury intrusion porosimetry (MIP) were determined. The different percentages of the precursors and the alkaline activators were optimised to produce paste samples. The compressive strength of samples with 10 vt.% EAF-Slag was close to 20.7 MPa after 90 curing days. The mechanical properties were further increased up to 30 MPa by increasing the percentage of EAF-Slag to 50 vt.%. This demonstrates a new potential for re-using waste material for various constructional applications.

scholarly journals Self-Sensing Properties of Green Alkali-Activated Binders with Carbon-Based Nanoinclusions

2020 ◽  
Vol 12 (23) ◽  
pp. 9916
Author(s):  
Antonella D’Alessandro ◽  
Denny Coffetti ◽  
Elena Crotti ◽  
Luigi Coppola ◽  
Andrea Meoni ◽  
...  
Keyword(s):  
Electrical Resistance ◽  
The Self ◽  
Compression Tests ◽  
Electromechanical Properties ◽  
Sensing Properties ◽  
The Matrix ◽  
Voltage Signal ◽  
Alkali Activated Binders ◽  
Alkali Activated ◽  
Carbon Based

This paper is aimed at investigating the self-sensing properties of Portland-free alkali-activated binders doped with carbon-based nanofillers. Four different inclusions (carbon nanotubes, carbon nanofibers, carbon black and graphene nanoplatelets) were added into the matrix in the same amount. The physical and electromechanical properties were analyzed. The self-sensing capabilities of the samples were tested by applying a square wave voltage signal and measuring the variation of electrical resistance during cyclical compression tests. The results showed that the presence of nano-inclusions enhanced the sensing behavior of the materials, especially regarding the linearity and the hysteresis performances. Such results appear promising for the application of such novel and innovative nano-modified composites in the field of monitoring structures and infrastructures.

EFFECT OF CURING TEMPERATURE ON THE PROPERTIES OF 100% CLAY-BASED GEOPOLYMER CONCRETE

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Muhammad Mukhlesur Rahman ◽  
David w. Law ◽  
Indubhushan Patnaikuni
Keyword(s):  
Structural Integrity ◽  
Curing Temperature ◽  
Superior Performance ◽  
Clay Material ◽  
Geopolymer Concrete ◽  
X Ray Diffraction ◽  
X Ray ◽  
Binder Material ◽  
Alkali Activated Binders ◽  
Alkali Activated

Substantial researches have already been carried out on alkali-activated binders for the production of geopolymer concrete but studies on clay-based geopolymer concrete is still insufficient. The aim of this paper is to identify the effect of curing temperature on the properties of 100% clay-based geopolymer concrete. Clay pre-treated at 80°C and 120°C for 24 hours were selected as the source binder material. Four Activator Modulus (AM); 1.0, 1.25, 1.5 and 1.75 for each of two Sodium Oxide (Na2O) dosages of 10% and 15% were selected as the activator material for this investigation. X-ray diffraction (XRF) was applied to characterize the clay material. Specimens were cured at 80°C and 120°C for 24 hours. Specimens were tested under compression at seven, 14, 28 and 40 days. Specimens cured at 80°C took a longer duration (>28 days) to achieve structural integrity while the specimens cured at 120°C achieved structural integrity within seven days. Compressive strength of specimens prepared with AM of 1.0 for both of the Na2O dosage of 10% and 15% exhibited superior performance to other AMs investigated.

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