scholarly journals The Incorporation of Steel Slag into Belite-Sulfoaluminate Cement Clinkers

2021 ◽  
Vol 11 (4) ◽  
pp. 1840
Author(s):  
Lea Žibret ◽  
Katarina Šter ◽  
Maruša Borštnar ◽  
Mojca Loncnar ◽  
Sabina Dolenec
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Rietveld Method ◽  
Isothermal Calorimetry ◽  
Steel Slag ◽  
Hydration Kinetics ◽  
Two Phase ◽  
Calcium Sulfoaluminate ◽  
Cement Clinkers ◽  
Potential Use

The potential use of steel slag from treated steel slag in belite-sulfoaluminate cements was investigated in this study. Cement clinkers with two phase compositions were synthesized, allowing the incorporation of different amounts of steel slag. The phase composition and microstructure of cement clinkers at three different sintering temperatures were studied by X-ray powder diffraction and the Rietveld method, as well as scanning electron microscopy with energy dispersive spectrometry. The results showed that the targeted phase composition of clinkers was achieved at a sintering temperature of 1250 °C. However, a higher amount of perovskite instead of ferrite was detected in the clinker with a higher content of Ti-bearing bauxite. Apart from the main phases, such as belite, calcium sulfoaluminate, and ferrite, several minor phases were identified, including mayenite, perovskite, periclase, and alkali sulfates. In both clinker mixtures, a higher content of MgO in the steel slags resulted in the formation of periclase. Furthermore, the hydration kinetics and compressive strength at 7 and 28 days were studied in two cements prepared from clinkers sintered at 1250 °C. As evidenced by the results of isothermal calorimetry, the hydration kinetics were also influenced by the minor clinker phases. Cement with a higher content of calcium sulfoaluminate phase developed a higher compressive strength.

scholarly journals The Influence of Superabsorbent Polymers and Nanosilica on the Hydration Process and Microstructure of Cementitious Mixtures

Materials ◽  
2020 ◽  
Vol 13 (22) ◽  
pp. 5194
Author(s):  
Gerlinde Lefever ◽  
Dimitrios G. Aggelis ◽  
Nele De Belie ◽  
Marc Raes ◽  
Tom Hauffman ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Isothermal Calorimetry ◽  
Autogenous Shrinkage ◽  
Hydration Process ◽  
Microstructural Development ◽  
Self Healing ◽  
Hydration Kinetics ◽  
Superabsorbent Polymers ◽  
Water To Cement Ratio ◽  
Supplementary Material

Superabsorbent polymers (SAPs) are known to mitigate the development of autogenous shrinkage in cementitious mixtures with a low water-to-cement ratio. Moreover, the addition of SAPs promotes the self-healing ability of cracks. A drawback of using SAPs lies in the formation of macropores when the polymers release their absorbed water, leading to a reduction of the mechanical properties. Therefore, a supplementary material was introduced together with SAPs, being nanosilica, in order to obtain an identical compressive strength with respect to the reference material without additives. The exact cause of the similar compressive behaviour lies in the modification of the hydration process and subsequent microstructural development by both SAPs and nanosilica. Within the present study, the effect of SAPs and nanosilica on the hydration progress and the hardened properties is assessed. By means of isothermal calorimetry, the hydration kinetics were monitored. Subsequently, the quantity of hydration products formed was determined by thermogravimetric analysis and scanning electron microscopy, revealing an increased amount of hydrates for both SAP and nanosilica blends. An assessment of the pore size distribution was made using mercury intrusion porosimetry and demonstrated the increased porosity for SAP mixtures. A correlation between microstructure and the compressive strength displayed its influence on the mechanical behaviour.

Effect of Steel Slag on Shrinkage Characteristics of Calcium Sulfoaluminate Cement

2021 ◽  
Vol 1036 ◽  
pp. 263-276
Author(s):  
Hao Ran Huang ◽  
Yi Shun Liao ◽  
Siraj Ai Qunaynah ◽  
Guo Xi Jiang ◽  
Da Wei Guo ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Relative Humidity ◽  
Cement Paste ◽  
Steel Slag ◽  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Chemical Shrinkage ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Slag Content

The effects of steel slag with 0, 10%, 20 % and 40% content on the chemical shrinkage, autogenous shrinkage, internal relative humidity, and drying shrinkage of calcium sulfoaluminate cement paste were studied. The results show that the compressive strength of calcium sulfoaluminate cement paste at an early stage decreases gradually when the content of steel slag increases. When the steel slag content is 0 and 10%, the compressive strength of hardened cement pastes gradually decreases at 90 and 180 days, but the samples with steel slag content of 20% and 40% maintain the compressive strength growth within 180 d. With the extension of curing period, the gap of compressive strength is gradually narrowed. The autogenous shrinkage decreases with the increase of steel slag content and has a good linear relationship with the relative humidity inside the paste. The proportion of autogenous shrinkage to chemical shrinkage is deficient, and most chemical shrinkage occurs in the form of the pore volume. Although the trends of drying shrinkage and autogenous are consistent, the former is more severe than the latter.

Effect of Anhydrite on the Early Hydration Performance of Rapid Setting and Hardening Belite Sulfoaluminate Cement

2017 ◽  
Vol 898 ◽  
pp. 1990-1995 ◽  
Author(s):  
Ming Zhang Lan ◽  
Bin Feng Xiang ◽  
Jian Feng Wang ◽  
Xu Dong Zhao ◽  
Xiao Ying Wang
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
High Strength ◽  
Cement Clinker ◽  
Hydration Kinetics ◽  
Early Hydration ◽  
Free Lime ◽  
Calcium Sulfoaluminate ◽  
Setting Times ◽  
Rapid Setting

In order to investigate the early hydration behavior of rapid setting and hardening belite sulfoaluminate cements, the methods of X-ray Diffraction, Scanning Electron Microscope, Compressive Strength test and Setting Times test were used to identify and quantify the hydration kinetics and microstructure of this new-found cements in China. The results showed that the main mineral compositions of high belite sulfoaluminate cement clinker included calcium sulfoaluminate (4CaO·3Al2O3·CaSO4), belite (2CaO·SiO2), ferrite phase, free gypsum and free lime. It was found that not only the setting time and compressive strength but also the composition of hydration products were influenced by anhydrite to some extent. Meanwhile, a mass of AFt and AFm generated along with the hydration process at different ages, overlapped, crossed and penetrated through calcium silicate hydrate gel and aluminum oxide to form a relatively dense structure which could contribute to the high strength of cement.

scholarly journals Effect of the Cooling Regime on the Mineralogy and Reactivity of Belite-Sulfoaluminate Clinkers

Minerals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 910
Author(s):  
Sabina Dolenec ◽  
Katarina Šter ◽  
Maruša Borštnar ◽  
Klara Nagode ◽  
Andrej Ipavec ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Isothermal Calorimetry ◽  
Bottom Ash ◽  
Quantitative Phase Analysis ◽  
X Ray Diffraction ◽  
Cooling Regime ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
Size And Morphology

This study investigated the influence of different cooling regimes on the microstructure and consequent reactivity of belite-sulfoaluminate clinkers. The cement clinkers were synthesized by incorporating secondary raw materials, such as titanogypsum and bottom ash, to the natural raw materials. Clinker phases were determined by Rietveld quantitative phase analysis, while the distribution morphology and the incorporation of substitute ions in the phases were characterized by scanning electron microscopy using energy-dispersive X-ray spectroscopy (SEM/EDS). Clinker reactivity was studied using isothermal calorimetry and was additionally investigated through compressive strength, which was determined for the cement prepared from the synthesized clinkers. X-ray diffraction analysis showed that, as well as the three main phases (belite, calcium sulfoaluminate, and ferrite), the clinkers contained additional minor phases (mayenite, gehlenite, arkanite, periclase, and perovskite), the ratios of which varied according to the cooling regime utilized. Microscopic observations indicated that the cooling regime also influenced the crystal size and morphology of the main phases, which consequently affected clinker reactivity. Furthermore, a smaller amount of substitute elements was incorporated in the main phases when cooling was slowed. Results showed that, in comparison to clinkers cooled at slower rates, air quenched clinkers reacted faster and exhibited a higher compressive strength at 7 days.

scholarly journals Development of a New Ecological Material Based on Moroccan Industrial Wastes for Road Construction

2020 ◽  
Author(s):  
Achraf Harrou ◽  
El Khadir Gharibi ◽  
Yassine Taha ◽  
Nathalie Fagel ◽  
Meriam El Ouahabi
Keyword(s):  
Compressive Strength ◽  
Steel Slag ◽  
Road Construction ◽  
Pozzolanic Reaction ◽  
Industrial Wastes ◽  
X Ray Diffraction ◽  
Hydration Kinetics ◽  
Hydrated Calcium Silicate ◽  
Pozzolanic Reactivity ◽  
Kinetics Of

The Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they were incorporated into bentonite (B) mixed with lime (L). The studied mixtures (BLW, BL-PG-W and BL-PG-Ss-W) were analyzed by X-ray diffraction, Infrared spectroscopy, Raman spectroscopy and SEM/EDX analysis. Compressive strength tests were performed on hardened specimens. The results obtained show that the hydration kinetics of the B-L-W and B-L-PG-W mixtures are slow. The addition of PG to a bentonite-lime mixture induces the formation of new microstructures such as hydrated calcium silicate (C-S-H) and ettringite, which increases the compressive strength of the cementitious specimens. The addition of the Ss to a mixture composed by 8%PG and 8%L-B accelerates the kinetics of hydration and activates the pozzolanic reaction. The presence of C2S in the slag helps to increase the mechanical strength of the mixture B-L-PG-Ss. The compressive strength of the mixtures BL-W, BL-PG-W and BL-PG-Ss-W increases from 15 to 28 days of setting. After 28 days of setting, 8% of Sc added to the mixture 8% PG-8%L-B is responsible for an increase of the compressive strength to 0.6 MPa.

scholarly journals Influence of Ultrasonication of Functionalized Carbon Nanotubes on the Rheology, Hydration, and Compressive Strength of Portland Cement Pastes

Materials ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5248
Author(s):  
Laura Silvestro ◽  
Artur Ruviaro ◽  
Geannina Lima ◽  
Paulo de Matos ◽  
Afonso R. G. de Azevedo ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Compressive Strength ◽  
Portland Cement ◽  
Mechanical Performance ◽  
Isothermal Calorimetry ◽  
Hydration Kinetics ◽  
Cement Pastes ◽  
Degree Of Hydration ◽  
Vis Spectroscopy ◽  
Localized Defects

The functionalization process usually increases the localized defects of carbon nanotubes (CNT). Thus, the ultrasonication parameters used for dispersing non-functionalized CNT should be carefully evaluated to verify if they are adequate in dispersing functionalized CNT. Although ultrasonication is widely used for non-functionalized CNT, the effect of this dispersing process of functionalized CNT has not been thoroughly investigated. Thus, this work investigated the effect of ultrasonication on functionalized CNT + superplasticizer (SP) aqueous dispersions by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), and Fourier transform infrared spectroscopy (FTIR). Furthermore, Portland cement pastes with additions of 0.05% and 0.1% CNT by cement weight and ultrasonication amplitudes of 0%, 50% and 80% were evaluated through rheometry, isothermal calorimetry, compressive strength at 1, 7 and 28 days, X-ray diffraction (XRD), and thermogravimetric analysis (TGA). FTIR results from CNT + SP dispersions indicated that ultrasonication may negatively affect SP molecules and CNT graphene structure. The increase in CNT content and amplitude of ultrasonication gradually increased the static and dynamic yield stress of paste but did not significantly affect its hydration kinetics. Compressive strength results indicated that the optimum CNT content was 0.05% by cement weight, which increased the strength of composite by up to 15.8% compared with the plain paste. CNT ultrasonication neither increases the degree of hydration of cement nor the mechanical performance of composite when compared with mixes containing unsonicated CNT. Overall, ultrasonication of functionalized CNT is not efficient in improving the fresh and hardened performance of cementitious composites.

scholarly journals The influence of calcium sulfate content on the hydration of belite-calcium sulfoaluminate cements with different clinker phase compositions

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Maruša Mrak ◽  
Frank Winnefeld ◽  
Barbara Lothenbach ◽  
Sabina Dolenec
Keyword(s):  
Compressive Strength ◽  
Calcium Sulfate ◽  
Pore Solution ◽  
Bound Water ◽  
Strength Development ◽  
Hydration Kinetics ◽  
Calcium Sulfoaluminate ◽  
Molar Ratios ◽  
Degree Of Reaction ◽  
Compressive Strength Development

AbstractThe influence of different amounts of gypsum on the hydration of a belite-rich and a ye'elimite-rich belite-calcium sulfoaluminate clinker (BCSA) was investigated. The hydration kinetics, phase assemblages and compressive strength development of cements prepared using ye’elimite/ calcium sulfate molar ratios of 1, 1.5 and 2 were studied. Besides ettringite and monosulfate, aluminium hydroxide, strätlingite, C−S−H, iron-containing siliceous hydrogarnet and hydrotalcite were present as hydration products. Increasing the amount of gypsum increased the ratio of ettringite to monosulfate formed in the cement paste, lowered the amount of pore solution, delayed the dissolution of belite and ferrite, decreased the formation of strätlingite and, in the case of the ye’elimite-rich BCSA, led to an increase in compressive strength. Increased amounts of belite in the clinker led to the formation of higher quantities of C–S–H, at the expense of strätlingite and a lower compressive strength, as belite has a lower degree of reaction than ye’elimite and due to the formation of more C–S–H and strätlingite compared to the more space-filling ettringite. The thermodynamic model established for BCSA cement hydration agrees well with the experimental data. Compressive strength directly correlated with bound water from thermogravimetric analyses and inversely correlated with the porosity calculated from thermodynamic modelling.

scholarly journals Evaluation of the use of steelmaking slag as an aggregate in concrete mix: A factorial design approach

2017 ◽  
Vol 23 (1) ◽  
pp. 113-119 ◽  
Author(s):  
Salah Aljbour ◽  
Sultan Tarawneh ◽  
Adnan Al-Harahsheh
Keyword(s):  
Compressive Strength ◽  
Factorial Design ◽  
Steel Slag ◽  
Aggregate Size ◽  
Steelmaking Slag ◽  
Mixed Medium ◽  
Concrete Mix ◽  
Input Variables ◽  
Full Factorial ◽  
Potential Use

Slag is investigated towards its potential use as an aggregate in concrete mix production. Full factorial design methodology is applied to study the effect of two process input variables, namely: slag as coarse aggregate and slag as medium aggregate on the properties of concrete mix. Additionally, the interaction between input variables is also examined. Incorporating steel slag aggregate in the concrete mix affected its compressive strength. Enhanced compressive strength concrete mix was obtained with 70 wt.% coarse slag aggregate and 70 wt.% medium slag aggregate. Under these proportions, the 28-days compressive strength was higher than the 28-days compressive strength of a concrete mix prepared from normal aggregate. Strong interaction effect exists between slag aggregate size on the compressive strength at 7-days curing. Lower compressive strength for the concrete mix might be obtained if improper proportions of mixed medium and coarse slag aggregate were employed.

Effect of Modifying Admixtures on the Cement System Hydration Kinetics

2015 ◽  
Vol 725-726 ◽  
pp. 487-492 ◽  
Author(s):  
Aleksey Adamtsevich ◽  
Andrey Pustovgar
Keyword(s):  
Phase Composition ◽  
Isothermal Calorimetry ◽  
Setting Time ◽  
Lithium Carbonate ◽  
Hydration Kinetics ◽  
Temperature Conditions ◽  
Cement System ◽  
Lower Temperature ◽  
The Impact

Presented are the results of the research on the impact of such factors as temperature conditions and cement phase composition on the effectiveness of hardening accelerators for concrete and other cement systems. The evaluation of the modifying elements effect has been performed by using the isothermal calorimetry method. This research revealed the selectivity of the admixtures impact when used together with different cement brands, as well as the possibility of increase setting time for cement systems in lower temperature conditions with the addition of Lithium carbonate based accelerator.

scholarly journals Phosphogypsum and Black Steel Slag as Additives for Ecological Bentonite-Based Materials: Microstructure and Characterization

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1067
Author(s):  
Achraf Harrou ◽  
El Khadir Gharibi ◽  
Yassine Taha ◽  
Nathalie Fagel ◽  
Meriam El Ouahabi
Keyword(s):  
Compressive Strength ◽  
Steel Slag ◽  
Pozzolanic Reaction ◽  
Industrial Wastes ◽  
X Ray Diffraction ◽  
Hydration Kinetics ◽  
Hydrated Calcium Silicate ◽  
Pozzolanic Reactivity ◽  
Strength Tests ◽  
Kinetics Of

The Black Steel slag (Ss) and phosphogypsum (PG) are industrial wastes produced in Morocco. In order to reduce these two wastes and to evaluate their pozzolanic reactivity in the presence of water, they were incorporated into bentonite (B) mixed with lime (L). The studied mixtures (BLW, BL–PG–W and BL–PG–Ss–W) were analyzed by X-ray diffraction, Infrared spectroscopy, Raman spectroscopy and SEM/EDX analysis. Compressive strength tests were performed on hardened specimens. The results obtained show that the hydration kinetics of the B–L–W and B–L–PG–W mixtures are slow. The addition of PG to a bentonite––lime mixture induces the formation of new microstructures such as hydrated calcium silicate (C–S–H) and ettringite, which increases the compressive strength of the cementitious specimens. The addition of the Ss to a mixture composed of 8%PG and 8%L–B accelerates the kinetics of hydration and activates the pozzolanic reaction. The presence of C2S in the slag helps to increase the mechanical strength of the mixture B–L–PG–Ss. The compressive strength of the mixtures BL–W, BL–PG–W and BL–PG–Ss–W increases from 15 to 28 days of setting. After 28 days of setting, 8% of Sc added to the mixture 8% PG–8%L–B is responsible for an increase of the compressive strength to 0.6 MPa.

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