scholarly journals Clayey Soil Strength Improvement by Using Alkali Activated Slag Reinforcing

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1076
Author(s):  
Darius Žurinskas ◽  
Danutė Vaičiukynienė ◽  
Gediminas Stelmokaitis ◽  
Viktoras Doroševas
Keyword(s):  
Shear Stress ◽  
Shear Strength ◽  
Clayey Soil ◽  
Fluorescence Analysis ◽  
Friction Angle ◽  
Soil Strength ◽  
Alkali Activated Slag ◽  
X Ray ◽  
Activated Slag ◽  
Alkali Activated

There are many studies related to using alkali activated binders for the improvement of clayey soil mechanical properties. In this study, alkali activated slag (AAS) for the improvement of clayey soil strength was used and it reinforced the clay. This paper presents results of an investigation on the utilization of ground-granulated blast-furnace slag in the reinforcement of clay soils. Therefore, significant cost savings could be achieved by using alkali activated slag as binding material. These samples were analyzed by X-Ray fluorescence analysis (XRF), X-Ray diffraction (XRD), scanning electron microscopy (SEM) and strength tests after the curing. The clay samples reinforced with AAS showed higher shear stress, cohesion and internal friction angle compared with the samples without reinforcement. The highest shear strength was achieved by using the highest amount of AAS (30%). This shear stress of the unreinforced clay samples could be increased from 63.2 to 137.4 kPa (117.4%) and from 123.2 to 257.4 kPa (108.9%) when the normal stress value of 100 and 500 kPa was used, respectively. The increase in shear strength is closely related to the compact contact zone between AAS and clay. Moreover, the new formed cementitious compounds of AAS had a positive influence on the shear strength of samples as well.

scholarly journals The Effect of Biochar on the Properties of Alkali-Activated Slag Pastes

2021 ◽  
Vol 2 (1) ◽  
pp. 1-14
Author(s):  
Joshua Prabahar ◽  
Babak Vafaei ◽  
Elvis Baffoe ◽  
Ali Ghahremaninezhad
Keyword(s):  
Computed Tomography ◽  
Autogenous Shrinkage ◽  
Absorption Kinetics ◽  
Effective Solution ◽  
Micro Computed Tomography ◽  
Alkali Activated Slag ◽  
X Ray ◽  
Void Structure ◽  
Activated Slag ◽  
Alkali Activated

This paper examines the influence of biochar on the properties of alkali-activated slag pastes using two activator solutions, namely NaOH and Na2CO3. The biochar demonstrated different absorption kinetics in the mixture of slag and the two activator solutions. The pastes with biochar showed a delay in the heat flow peak, compared to the pastes without biochar, but the cumulative heat release in these pastes at later hours was increased, compared to the pastes without biochar. It was found that the use of biochar reduced autogenous shrinkage in the pastes and the reduction in autogenous shrinkage was more pronounced in the alkali-activated slag with NaOH, compared to Na2CO3. The void structure of the pastes was investigated using x-ray micro-computed tomography. It was found that refined pore structure due to reduced effective solution/slag in the pastes with biochar was able to compensate for the decreasing effect of biochar voids on compressive strength. The electrical resistivity was shown to be lower in the pastes with biochar.

scholarly journals Strength Development and Microstructure of Alkali-activated Slag-MgO in Air Curing Condition

2018 ◽  
Vol 186 ◽  
pp. 02003
Author(s):  
Chao-Lung Hwang ◽  
Duy-Hai Vo ◽  
Mitiku Damtie Yehualaw ◽  
Vu-An Tran
Keyword(s):  
Compressive Strength ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Alkali Activated Slag ◽  
X Ray ◽  
Binder Ratio ◽  
Curing Condition ◽  
Activated Slag ◽  
Water To Binder Ratio ◽  
Alkali Activated

The aim of this study is to analysis the effect of MgO on strength development and microstructure of alkali-activated slag (AAS) in air curing condition. Four mixtures of AAS are prepared using different MgO content (0%, 5%, 10%, and 15 % by weight of slag) at water to binder ratio of 0.4. The flow, compressive strength, scanning electron microscopy, and X-ray diffraction are tested under relevant standards. The addition of MgO significantly accelerated the hydration rate of AAS. AAS with adding MgO tended to increase the compressive strength and to reduce the flow. The higher adding MgO content was associated with higher hydrotalcite-like phase (Ht) formation which improved the microstrure of AAS in the air curing condition.

scholarly journals Effects of CO2 Curing on Alkali-Activated Slag Paste Cured in Different Curing Conditions

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3513 ◽  
Author(s):  
Yubin Jun ◽  
Seong Ho Han ◽  
Tae Yong Shin ◽  
Jae Hong Kim
Keyword(s):  
Compressive Strength ◽  
Co2 Concentration ◽  
Strength Development ◽  
X Ray Diffraction ◽  
Curing Conditions ◽  
Alkali Activated Slag ◽  
X Ray ◽  
Compressive Strength Development ◽  
Activated Slag ◽  
Alkali Activated

The effect of CO2 curing on alkali-activated slag paste activated by a mixture of sodium hydroxide and sodium silicate solutions is reported in this paper. The paste samples after demolding were cured in three different curing environments as follows: (1) environmental chamber maintained at 85% relative humidity (RH) and 25 °C; (2) 3-bar CO2 pressure vessel; and (3) CO2 chamber maintained at 20% CO2 concentration, 70% RH and 25 °C. The hardened samples were then subjected to compressive strength measurement, X-ray diffraction analysis, and thermogravimetry. All curing conditions used in this study were beneficial for the strength development of the alkali-activated slag paste samples. Among the curing environments, the 20% CO2 chamber was the most effective on compressive strength development; this is attributed to the simultaneous supply of moisture and CO2 within the chamber. The results of X-ray diffraction and thermogravimetry show that the alkali-activated slag cured in the 20% CO2 chamber received a higher amount of calcium silicate hydrate (C-S-H), while calcite formed at an early age was consumed with time. C-S-H was formed by associating the calcite generated by CO2 curing with the silica gel dissolved from alkali-activated slag.

Experimental studies on shear strength characteristics of alkali activated slag concrete mixes

2020 ◽  
Vol 27 ◽  
pp. 275-279
Author(s):  
R. Manjunath ◽  
Mattur C. Narasimhan ◽  
M. Shashanka ◽  
S.D. Vijayanand ◽  
J. Vinayaka
Keyword(s):  
Shear Strength ◽  
Experimental Studies ◽  
Strength Characteristics ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

Influence of Polymer Admixtures on the Rheological Properties and Heat of Hydration of Alkali Activated Slag Pastes

2018 ◽  
Vol 276 ◽  
pp. 217-222
Author(s):  
Olesia Mikhailova ◽  
Pavel Rovnaník
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Heat Of Hydration ◽  
Hydration Process ◽  
Alkali Activated Slag ◽  
Activated Slag ◽  
Alkali Activated

The purpose of this study is to investigate the rheological properties of alkali-activated slag prepared as a paste modified by various amount of polymer admixtures. Four commercial admixtures VINNAPAS®5023 L, 5111 L, 7016 F and 7220 E were used as polymer admixture in this study. These admixtures were incorporated to alkali activated slag pastes in quantities between 0.5 and 2% by mass of slag. Rheological properties as shear stress and viscosity of fresh pastes were examined by Discovery HR-1. Another main focus of this paper is the effect of selected admixtures on the heat of hydration of an alkali activated slag. Results indicate that addition of polymer admixtures affects the viscosity of the pastes and hydration process.

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