Chemical Activation of Cementing Properties of Granulated Blast Furnace Slags

2012 ◽  
Vol 454 ◽  
pp. 11-16
Author(s):  
Xian Jun Lu ◽  
Shu Gang Hu ◽  
Zi Qiao Jin
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Amorphous Materials ◽  
Chemical Activation ◽  
Xrd Analysis ◽  
Hydration Products ◽  
X Ray ◽  
Early Strength ◽  
Activated Slag ◽  
Alkali Activated

Using CaO, NaOH and Na2CO3 as activators, the effects of dosage and combination of the activators on the cementing property of granulated blast furnace slags were investigated, and the hydration products of the activated slags were detected by X-ray powder diffraction (XRD) analysis. Results indicate that CaO can be used as an effective activator for the slag samples and its optimum dosage is about 10%, but the CaO activated slags shows much lower early strength than the Portland cement. However, the early strength of the CaO activated slag can be remarkably improved by the addition of NaOH or Na2CO3. Under the addition of about 6% NaOH or Na2CO3, the overall compressive strength of the alkali activated slag is higher than a 42.5MPa Portland cement. XRD analysis revealed that the hydration products of the alkali activated slags are mainly amorphous materials, which is quite different from that of the Portland cement.

High Strength Alkali Activated Slag Cements with Controlled Setting Times and Early Strength Gain

2015 ◽  
Vol 1100 ◽  
pp. 44-49 ◽  
Author(s):  
Pavel Krivenko ◽  
Oleg Petropavlovsky ◽  
Vit Petranek ◽  
Vasiliy Pushkar ◽  
Grigorii Vozniuk
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Water Glass ◽  
High Strength ◽  
Strength Gain ◽  
Setting Times ◽  
Alkaline Activator ◽  
Early Strength ◽  
Activated Slag ◽  
Alkali Activated

The paper discusses approaches to compositional build-up of high strength alkali activated cements made using water glass as alkaline activator represented by commercial products in a form of powder and liquid. The purpose was to study the influence of fineness of ground granulated blast-furnace slags, admixtures and additives, compatible with alkali activated cements, water glass and mode of manufacturing technology in order to reach high compressive strength (≥ 80 MPa at standard age (28 days)) and early strength (≥ 20 MPa after 3 h of hardening in normal conditions).

scholarly journals Effects of Highly Crystalized Nano C-S-H Particles on Performances of Portland Cement Paste and Its Mechanism

Crystals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 816
Author(s):  
Yuli Wang ◽  
Huijuan Lu ◽  
Junjie Wang ◽  
Hang He
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Setting Time ◽  
Tricalcium Silicate ◽  
Strength Development ◽  
Early Age ◽  
Hydration Products ◽  
X Ray ◽  
Early Strength ◽  
Portland Cement Paste

In order to improve the early age strength of ordinary Portland cement-based materials, many early strength agents were applied in different conditions. Different from previous research, the nano calcium silicate hydrate (C-S-H) particles used in this study were synthesized through the chemical reaction of CaO, SiO2, and H2O under 120 °C using the hydrothermal method, and the prepared nano C-S-H particles were highly crystalized. The influences of different amounts of nano C-S-H particles (0%, 0.5%, 1%, 2% and 3% by weight of cement) on the setting time, compressive strength, and hydration heat of cement paste were studied. The hydration products and microstructure of the cement paste with different additions of nano C-S-H particles were investigated through thermogravimetry-differential thermal analysis (TG-DTA), X-ray powder diffraction (XRD), and scanning electron microscope (SEM) tests. The results show that the nano C-S-H particles could be used as an early strength agent, and the early strength of cement paste can be increased by up to 43% through accelerating the hydration of tricalcium silicate (C3S). However, the addition of more than 2% nano C-S-H particles was unfavorable to the later strength development due to more space being left during the initial accelerated hydration process. It is suggested that the suitable content of the nano C-S-H particles is 0.5%−1% by weight of cement.

scholarly journals Autogenous Deformation of Alkali-Activated Blast Furnace Slag Concrete Subjected to Variable Curing Temperatures

2019 ◽  
Vol 2019 ◽  
pp. 1-8 ◽  
Author(s):  
Katalin Orosz ◽  
Abeer Humad ◽  
Hans Hedlund ◽  
Andrzej Cwirzen
Keyword(s):  
Blast Furnace ◽  
Diffraction Analysis ◽  
Sodium Silicate ◽  
Blast Furnace Slag ◽  
Curing Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Activated Slag ◽  
Furnace Slag ◽  
Alkali Activated

Deformations of alkali-activated slag concrete (AASC) with high MgO and Al2O3 content, subjected to variable curing temperature were studied. Sodium silicate and sodium carbonate were used as alkali activators. The obtained results showed development of deformations consisting of both shrinkage and expansion. Shrinkage appeared not to be affected by the activator type, while the expansion developed after the cooling down phase in stabilized isothermal conditions and did not stop within the duration of the tests. X-ray diffraction analysis performed shortly after the cooling down phase indicated the formation of crystalline hydrotalcite, which was associated with the observed expansion. A mixture with a higher amount of sodium silicate showed less expansion, likely due to the accelerated hydration and geopolymerization leading to the increased stiffness of the binder matrix.

Possibilities of Processing of Slag Aggregate from Heap Koněv

2019 ◽  
Vol 292 ◽  
pp. 79-84
Author(s):  
Lukáš Procházka ◽  
Jana Boháčová
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Mechanical Parameters ◽  
Durability Properties ◽  
Subsequent Determination ◽  
Alkali Activated

The aim of this work is to find out whether the slag aggregates from heap Koněv can be used in hydraulic mixtures based on traditional Portland cement as well as in alternative binders based on alkali activated blast furnace slag.In the experiment the basic physical-mechanical parameters of prepared mixtures were determined and the durability properties of these composites were verified. The composition of the aggregate extract and its influence on the properties of the prepared mixtures and the subsequent determination of the alkaline ions in slag aggregates were also verified.

scholarly journals Geopolymer Based on Mechanically Activated Air-cooled Blast Furnace Slag

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1134 ◽  
Author(s):  
Ilda Tole ◽  
Magdalena Rajczakowska ◽  
Abeer Humad ◽  
Ankit Kothari ◽  
Andrzej Cwirzen
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Portland Cement ◽  
Sodium Silicate ◽  
Blast Furnace Slag ◽  
Ball Mill ◽  
Efficient Solution ◽  
Building Materials ◽  
Furnace Slag ◽  
Alkali Activated

An efficient solution to increase the sustainability of building materials is to replace Portland cement with alkali-activated materials (AAM). Precursors for those systems are often based on water-cooled ground granulated blast furnace slags (GGBFS). Quenching of blast furnace slag can be done also by air but in that case, the final product is crystalline and with a very low reactivity. The present study aimed to evaluate the cementitious properties of a mechanically activated (MCA) air-cooled blast furnace slag (ACBFS) used as a precursor in sodium silicate alkali-activated systems. The unreactive ACBFS was processed in a planetary ball mill and its cementing performances were compared with an alkali-activated water-cooled GGBFS. Mixes based on mechanically activated ACBFS reached the 7-days compressive strength of 35 MPa and the 28-days compressive strength 45 MPa. The GGBFS-based samples showed generally higher compressive strength values.

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