scholarly journals Cement Kiln By-Pass Dust: An Effective Alkaline Activator for Pozzolanic Materials

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1770 ◽  
Author(s):  
Lukáš Kalina ◽  
Vlastimil Bílek ◽  
Tomáš Kiripolský ◽  
Radoslav Novotný ◽  
Jiří Másilko
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Autogenous Shrinkage ◽  
Cement Industry ◽  
Strength Development ◽  
Cement Kiln ◽  
Binder Phase ◽  
Fine Grained ◽  
Furnace Slag ◽  
Alkali Activated

Cement kiln by-pass dust (CKD) is a fine-grained by-product of Portland clinker manufacturing. Its chemical composition is not suitable for returning back into feedstock and, therefore, it has to be discharged. Such an increasing waste production contributes to the high environmental impact of the cement industry. A possible solution for the ecological processing of CKD is its incorporation into alkali-activated blast furnace slag binders. Thanks to high alkaline content, CKD serves as an effective accelerator for latent hydraulic substances which positively affect their mechanical properties. It was found out that CKD in combination with sodium carbonate creates sodium hydroxide in situ which together with sodium water glass content increases the dissolution of blast furnace slag particles and subsequently binder phase formation resulting in better flexural and compressive strength development compared to the sample without it. At the same time, the addition of CKD compensates the autogenous shrinkage of alkali-activated materials reducing the risk of material cracking. On the other hand, this type of inorganic admixture accelerates the hydration process causing rapid loss of workability.

Strength and Porosity of Materials on the Basis of Blast Furnace Slag Activated by Liquid Sodium Silicate

2016 ◽  
Vol 851 ◽  
pp. 45-50 ◽  
Author(s):  
Vlastimil Bílek Jr. ◽  
Ladislav Pařízek ◽  
Petr Kosár ◽  
Jiří Kratochvíl ◽  
Lukáš Kalina
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Liquid Sodium ◽  
Cement Kiln ◽  
Early Age ◽  
Fluidized Bed Combustion ◽  
Shrinkage Reducing Admixture ◽  
Kiln Dust ◽  
Furnace Slag ◽  
Alkali Activated

This study investigates the effect of different admixtures on strength and porosity development of mortars and pastes based on alkali activated blast furnace slag (AABFS). Fluidized bed combustion fly ash and by-pass cement kiln dust were used to replace slag in the binder by 5%wt. and 10%wt., respectively. Pure slag mortar was also modified by a shrinkage reducing admixture. The use of all the admixtures resulted in a reduction in early age strength, while only shrinkage reducing admixture had significant impact on pore size distribution. Properties of AABFS based specimens were compared to those of specimens based on ordinary Portland cement (OPC).

scholarly journals Compressive Strength and Microstructure Properties of Alkali-Activated Systems with Blast Furnace Slag, Desulfurization Slag, and Gypsum

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Bong-Suk Cho ◽  
Kyung-Mo Koo ◽  
Se-Jin Choi
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Construction Material ◽  
Steel Slag ◽  
Steel Production ◽  
Value Added ◽  
Cement Industry ◽  
Furnace Slag ◽  
Alkali Activated

This study investigates the effect of desulfurization slag (DS) and gypsum (G) on the compressive strength and microstructure properties of blast furnace slag-(BFS-) based alkali-activated systems. DS is produced in a Kambara reactor process of molten iron produced in a steel production process. DS contains CaO, SiO2, Fe2O3, and SO3 and is composed of Ca(OH)2 and 2CaO·SiO2 as main compounds. In this investigation, the weight of BFS was replaced by DS at 5, 10, 15, 20, 25, and 30%. In addition, G was also applied at 9, 12, and 15% by weight of BFS to improve the compressive strength of the alkali-activated system with BFS and DS. According to this investigation, the compressive strength of the alkali-activated mixes with BFS and DS ranged from 14.9 MPa (B95D5) to 19.8 MPa (B90D10) after 91 days. However, the 28 days compressive strength of the alkali-activated mixes with BFS, DS, and G reached 39.1 MPa, 45.2 MPa, and 48.4 MPa, respectively, which were approximately 78.8 to 97.5% of that of O100 mix (49.6 MPa). The main hydrates of the BFS-DS (B80D20) binder sample were Ca(OH)2, CaCO3, and low-crystalline calcium silicate hydrates, while the main hydration product of BFS-DS-G (B75D10G15) binder was found as ettringite. The use of BFS-DS-G binders would result in the value-added utilization of steel slag and provide an environmentally friendly construction material, and contribute to a reduction of CO2 in the cement industry.

scholarly journals Modification of Alkali Activated Blast Furnace Slag for Pothole Repairs

2019 ◽  
Vol 274 ◽  
pp. 04003
Author(s):  
Minna Sarkkinen ◽  
Kauko Kujala ◽  
Seppo Gehör
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Negative Impact ◽  
Positive Impact ◽  
Optimization Method ◽  
Strength Development ◽  
The Impact ◽  
Furnace Slag ◽  
Alkali Activated

Potholes denote small, typically sharp edged holes in the pavement. The aim of this research was to study the usability of alkali activated (AA) blast furnace slag based material in the repair of paved roads, especially during the cold winter and spring seasons when such repairs are needed most and the use of hot asphalt is not possible. The objective was to a find material which is both more cost-efficient and durable than plain cold asphalt. Properties like rapid strength development, good bonding with old paving material, weather resistance, abrasion resistance, and low shrinkage were required. The influence of the chosen factors on the performance of the material was studied applying the multi-attribute optimization method. The impact of different additives, such as Portland cement, fibers and crushed tire rubber were studied. The results indicated that the AA slag based materials studied can be improved by suitable additives to make them reach desired performance. According to the tests, adding Portland cement increased compressive strength threefold after 3 hours and reduced shrinkage by 34% but should be a negative impact on higher levels related to freeze-thaw resistance. In addition, crushed rubber was indicated to have a positive impact related to all the studied performance properties.

scholarly journals Influence of Steel Slag-Superfine Blast Furnace Slag Composite Mineral Admixture on the Properties of Mortar and Concrete

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Zhenguo Liu ◽  
Zongxian Huang
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Steel Slag ◽  
Autogenous Shrinkage ◽  
Mineral Admixture ◽  
Strength Development ◽  
Adiabatic Temperature Rise ◽  
Solid Ratio ◽  
Composite Mixture ◽  
Furnace Slag

A composite mineral admixture was prepared by steel slag and superfine blast furnace slag. The influence of superfine blast furnace slag content of the composite mixture on the mortar and concrete was investigated. The results show that the composite mineral admixture may decrease the strength of concrete at the early age but improve the strength development over time. Increasing the content of superfine blast furnace slag can reduce the degradation of the early strength. The reduction of the autogenous shrinkage and adiabatic temperature rise is significant when the composite mineral admixture is added. The reduction is more obvious when the water-to-solid ratio (w/s) is low. The results show that with steel slag and superfine blast furnace slag playing as complementary parts in the composite mineral admixture, it can be used as an effective substitute of cement.

scholarly journals Control of the setting reaction and strength development of slag-blended volcanic ash-based phosphate geopolymer with the addition of boric acid

2021 ◽  
Author(s):  
Jean Noël Yankwa Djobo ◽  
Dietmar Stephan
Keyword(s):  
Blast Furnace ◽  
Boric Acid ◽  
Blast Furnace Slag ◽  
Volcanic Ash ◽  
Strength Development ◽  
Main Process ◽  
Reaction Products ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

AbstractThis work aimed to evaluate the role of the addition of blast furnace slag for the formation of reaction products and the strength development of volcanic ash-based phosphate geopolymer. Volcanic ash was replaced by 4 and 6 wt% of ground granulated blast furnace slag to accelerate the reaction kinetics. Then, the influence of boric acid for controlling the setting and kinetics reactions was also evaluated. The results demonstrated that the competition between the dissolution of boric acid and volcanic ash-slag particles is the main process controlling the setting and kinetics reaction. The addition of slag has significantly accelerated the initial and final setting times, whereas the addition of boric acid was beneficial for delaying the setting times. Consequently, it also enhanced the flowability of the paste. The compressive strength increased significantly with the addition of slag, and the optimum replaced rate was 4 wt% which resulted in 28 d strength of 27 MPa. Beyond that percentage, the strength was reduced because of the flash setting of the binder which does not allow a subsequent dissolution of the particles and their precipitation. The binders formed with the addition of slag and/or boric acid are beneficial for the improvement of the water stability of the volcanic ash-based phosphate geopolymer.

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