scholarly journals Hydration Characteristics of Tricalcium Aluminate in the Presence of Nano-Silica

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 199
Author(s):  
Dapeng Zheng ◽  
Manuel Monasterio ◽  
Weipeng Feng ◽  
Waiching Tang ◽  
Hongzhi Cui ◽  
...  
Keyword(s):  
Isothermal Calorimetry ◽  
Pozzolanic Reaction ◽  
Nano Silica ◽  
Hydration Kinetics ◽  
Reactive Component ◽  
Nano Sio2 ◽  
Pozzolanic Reactivity ◽  
Tricalcium Aluminate ◽  
Hydration Characteristics ◽  
Kinetics Of

Tricalcium aluminate (C3A) is the most reactive component of the Portland cement and its hydration has an important impact on the workability and early strength of concrete. Recently, nanomaterials such as nano-silica (nano-SiO2) have attracted much attention in cement-based materials because of its pozzolanic reactivity and the pore-filling effect. However, its influence on the hydration of C3A needs to be well understood. In this study, the hydration kinetics of C3A mixed with different percentages of nano-SiO2 were studied and compared with pure C3A. The hydration products were examined by different characterization techniques including XRD, XPS, and NMR spectroscopy and isothermal calorimetry analyses. The XRD results showed that the addition of nano-SiO2 promoted the conversion of the intermediate product C4AH13. The isothermal calorimetry results showed that the addition of nano-SiO2 significantly reduced the hydration exotherm rate of C3A from 0.34 to less than 0.1 mW/g. With the presence of nano-SiO2, the peaks for Q1 were observed in 29Si MAS-NMR measurements, and the content of Q1 increased from 6.74% to 30.6% when the nano-SiO2 content increased from 2 wt.% to 8 wt.%, whereas the proportion of Q4 gradually decreased from 89.1% to 63.6%. These results indicated a pozzolanic reaction provoked by the nano-SiO2 combined with aluminate structures generating C-A-S-H gel.

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 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.

scholarly journals Influence of Glass Powder on Hydration Kinetics of Composite Cementitious Materials

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
Xiaolin Chang ◽  
Xinping Yang ◽  
Wei Zhou ◽  
Guoshuai Xie ◽  
Shuhua Liu
Keyword(s):  
Glass Powder ◽  
Isothermal Calorimetry ◽  
Cementitious Materials ◽  
Heat Emission ◽  
Hydration Heat ◽  
Hydration Kinetics ◽  
Period Increase ◽  
Acceleration Period ◽  
Boundary Reaction ◽  
Kinetics Of

The influence of glass powder (GP) on hydration kinetics of composite cementitious materials has been investigated by isothermal calorimetry test and hydration kinetics methods in this paper. The hydration heat emission rate and hydration heat decrease gradually while the induction and acceleration period increase with the increase of GP content. According to Krstulovic-Dabic model, the hydration process of composite cementitious materials containing GP is controlled by a variety of complicated reaction mechanisms, which can be divided into three periods: nucleation and crystal growth (NG), phase boundary reaction (I), and diffusion (D). The NG and I process are shortened after incorporating GP.

Sign in / Sign up

Export Citation Format

Share Document