scholarly journals Effect of alkali cation type on the plasticizing effect of ligno-sulfonate in alkali-activated systems

2021 ◽  
Vol 1205 (1) ◽  
pp. 012016
Author(s):  
V Iliushchenko ◽  
V Bilek Jr. ◽  
L Kalina ◽  
P Hruby ◽  
T Opravil ◽  
...  
Keyword(s):  
Rheological Properties ◽  
Blast Furnace Slag ◽  
Dry Matter ◽  
Oscillation Amplitude ◽  
Granulated Blast Furnace Slag ◽  
Cation Type ◽  
Alkaline Activator ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Slag Weight

Abstract The rheological properties of alkali-activated systems are significantly affected by the nature of the alkaline activator. Hydroxide-activated systems’ workability is typically lower than that of alkali-activated systems but can be improved by lignosulfonate plasticizer. However, the lignosulfonate plasticizer’s effectivity depends on the dosage of lignosulfonate, the nature of hydroxide and pH of their solutions. Therefore, in this study, the effectiveness of lignosulfonate plasticizer with respect to alkali ion type (Na+, K+, Li+) in alkali hydroxide-activated systems based on ground granulated blast furnace slag was evaluated. The concentration of the alkaline activator (NaOH, KOH and LiOH) was the same in all cases of 4M. The superplasticizer dosage was 0%, 0.5% and 1.0% of dry matter of lignosulfonate plasticizer to the slag weight. Rheological properties were determined using a rotational rheometer equipped with vane in-cup geometry working in oscillation amplitude sweep mode, from which critical strain and corresponding viscoelastic variables were obtained.

scholarly journals Décalcification resistance of various alkali-activated materials

2021 ◽  
Vol 1205 (1) ◽  
pp. 012015
Author(s):  
P Hruby ◽  
V Bilek ◽  
L Topolar ◽  
L Kalina ◽  
M Marko ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace Slag ◽  
Significant Loss ◽  
Granulated Blast Furnace Slag ◽  
Loss Of Mass ◽  
Sodium Waterglass ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Reference Samples ◽  
Slag Weight

Abstract The resistance of alkali-activated materials (AAMs) to degradation processes, particularly the decalcification, was studied in this paper. The ground granulated blast furnace slag was alkali-activated using various activators with the same activator dosage 6% Na2O by slag weight (sodium hydroxide, sodium waterglass and sodium carbonate) and subjected to testing of decalcification resistance (immersion in 6M NH4 NO3) for 84 days. The reference samples were stored in water. The progress of degradation was studied using the phenolphthalein technique, mechanical properties testing (compressive and flexural strength), and dilatometry analysis or weight measurements. The results obtained were compared to the CEM III/A 32.5R. The significant loss of mass along with the deterioration of mechanical properties were observed for all binder types, still some of the AAMs showed better durability than the cementitious one.

Effect of the Combined Using of Fly Ash and Granulated Blast Furnace Slag on Properties of Cementless Alkali-Activated Mortar

2011 ◽  
Vol 287-290 ◽  
pp. 916-921
Author(s):  
Kyung Taek Koh ◽  
Gum Sung Ryu ◽  
Si Hwan Kim ◽  
Jang Hwa Lee
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Curing Temperature ◽  
Mixture Ratio ◽  
Granulated Blast Furnace Slag ◽  
Alkaline Activator ◽  
Furnace Slag ◽  
Alkali Activated

This paper examines the effects of the mixture ratio of fly ash/slag, the type of alkaline activators and curing conditions on the workability, compressive strength and microstructure of cementless alkali-activated mortar. The investigation showed that the mixture ratio of fly ash/slag and the type of alkaline activator have significant influence on the workability and strength, whereas the curing temperature has relatively poor effect. An alkali-activated mortar using a binder composed of 50% of fly ash and 50% of granulated blast furnace slag and alkaline activator made of 9M NaOH and sodium silicate in proportion of 1:1 is seen to be able to develop a compressive strength of 65 MPa at age of 28 days even when cured at ambient temperature of 20°C.

scholarly journals Synthesis of Ambient Cured GGBFS Based Alkali Activated Binder Using a Sole Alkaline Activator: A Feasibility Study

2021 ◽  
Vol 11 (13) ◽  
pp. 5887
Author(s):  
Thandiwe Sithole ◽  
Nelson Tsotetsi ◽  
Tebogo Mashifana
Keyword(s):  
Silicate Solution ◽  
Environmental Footprint ◽  
Ambient Temperatures ◽  
Granulated Blast Furnace Slag ◽  
Naoh Solution ◽  
Alkaline Activator ◽  
Porous Morphology ◽  
Furnace Slag ◽  
Alkali Activated

Utilisation of industrial waste-based material to develop a novel binding material as an alternative to Ordinary Portland Cement (OPC) has attracted growing attention recently to reduce or eliminate the environmental footprint associated with OPC. This paper presents an experimental study on the synthesis and evaluation of alkali activated Ground granulated blast furnace slag (GGBFS) composite using a NaOH solution as an alkaline activator without addition of silicate solution. Different NaOH concentrations were used to produce varied GGBFS based alkali activated composites that were evaluated for Uncofined Compressive Strength (UCS), durability, leachability, and microstructural performance. Alkali activated GGBFS composite prepared with 15 M NaOH solution at 15% L/S ratio achieved a UCS of 61.43 MPa cured for 90 days at ambient temperatures. The microstructural results revealed the formation of zeolites, with dense and non-porous morphology. Alkali activated GGBFS based composites can be synthesized using a sole alkaline activator with potential to reduce CO2 emission. The metal leaching tests revealed that there are no potential environmental pollution threats posed by the synthesized alkali activated GGBFS composites for long-term use.

scholarly journals Microstructure Features of Ternary Alkali-activated Binder Based on Tungsten Mining Waste, Slag and Metakaolin

2020 ◽  
Author(s):  
Naim Sedira ◽  
João Castro-Gomes
Keyword(s):  
Sodium Silicate ◽  
Room Temperature ◽  
Mining Waste ◽  
Dense Matrix ◽  
Microstructural Properties ◽  
Reaction Products ◽  
Granulated Blast Furnace Slag ◽  
Alkaline Activator ◽  
Furnace Slag ◽  
Alkali Activated

This study determines the effect of ground granulated blast furnace slag (GGBFS) and metakaolin (MK) on the microstructural properties of the tungsten mining waste-based alkali-activated binder (TMWM). During this investigation, TMWM was partially replaced with 10 wt.% GGBFS and 10 wt.% MK to improve the microstructure of the binder. In order to understand the effect of the substitutions on the microstructure, two pastes were produced to make a comparative study between the sample contain 100% TMWM and the ternary precursors. Both precursors were activated using a combination of alkaline activator solutions (sodium silicate and sodium hydroxide) with the ratio of 1:3 (66.6 wt.% sodium silicate combined with 33.33 wt.% of NaOH 8M). The alkali-activated mixes were cured in oven at temperature of 60 °C in the first day and at room temperature for the next 27 days. The reaction products N-A-S-H gel and (N,M)-A-S-H gel resulted from the alkaline activation reaction process. In addition, a formation of natrite (Na2CO3) with needles shape occurred as a reaction product of the fluorescence phenomena. However, a dense matrix resulted from the alkline activation of the ternary precursors containg different gels such as N-A-S-H, C-A-S-H and (N,M)-C-A-S-H gel, these results were obtained through SEM-EDS analyses, as well FTIR tests. Keywords: Mining Waste, Alkali-activated, Microstructure, Slag, Metakaolin

scholarly journals The efficiency of plasticizing surfactants in alkali-activated cement mortars and concretes

2018 ◽  
Vol 230 ◽  
pp. 03016 ◽  
Author(s):  
Raisa Runova ◽  
Volodymyr Gots ◽  
Igor Rudenko ◽  
Oleksandr Konstantynovskyi ◽  
Oles’ Lastivka
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Chemical Nature ◽  
Granulated Blast Furnace Slag ◽  
Cement Mortars ◽  
Alkaline Component ◽  
Property Modification ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Strength In Bending

Functionality of mortar and concrete mixes is regulated by surfactants, which act as plasticizers. The molecular structure of these admixtures can be changed during hydration of alkali-activated cements (AAC). The objective was to determine the chemical nature of plasticizers effective for property modification of mortars and concretes based on AACs with changing content of granulated blast furnace slag from 0 to 100 %. The admixtures without ester links become more effective than polyesters when content of alkaline component increase. The admixtures effective in high alkaline medium were used in dry mixes for anchoring (consistency of mortar 150 mm by Vicat cone; 1 d tensile strength in bending / compressive strength of mortar 6.6 /30.6 MPa) and in ready-mixed concretes (consistency class changed from S1 to S3, S4 with consistency safety during 60 min; 3 d compressive strength of modified concrete was not less than the reference one without admixtures).

Comparison of Selected Properties of Portland Cement Based Materials and Alkali Activated Materials Based on Granulated Blast Furnace Slag

2016 ◽  
Vol 865 ◽  
pp. 107-113 ◽  
Author(s):  
Pavel Mec ◽  
Jana Boháčová ◽  
Josef Koňařík
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Water Glass ◽  
Sodium Metasilicate ◽  
Alkali Activation ◽  
Granulated Blast Furnace Slag ◽  
Cement Based Materials ◽  
One Year ◽  
Furnace Slag ◽  
Alkali Activated

Alkali activated systems are materials formed by alkali-activation of latent hydraulic or pozzolanic materials. The outcome is a polymeric structure with properties comparable to materials based on cement.The principle of the experiment is to compare selected properties of alkali-activated materials based on blast furnace slag and using various types of activator (sodium water glass, potassium water glass, DESIL AL and sodium metasilicate) to binders based on white and Portland cements of the highest quality. The samples were left for one year in environments simulating the conditions in the interior and exterior. Selected physical-mechanical properties were evaluated and compared.

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