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.

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.

Mechanical properties of alkali activated blast furnace slag pastes reinforced with carbon fibers

2016 ◽  
Vol 116 ◽  
pp. 63-71 ◽  
Author(s):  
J.L. Vilaplana ◽  
F.J. Baeza ◽  
O. Galao ◽  
E.G. Alcocel ◽  
E. Zornoza ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Blast Furnace ◽  
Carbon Fibers ◽  
Blast Furnace Slag ◽  
Furnace Slag ◽  
Alkali Activated

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).

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