scholarly journals Influence of Different Lithium Compounds on Hydration and Mechanical Properties of Calcium Sulfoaluminate Cement

Materials ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 3465
Author(s):  
Hongyang Deng ◽  
Xuanchun Wei ◽  
Shaoyan Liu ◽  
Shan Li ◽  
Xinhua Cai
Keyword(s):  
Mechanical Properties ◽  
Lithium Carbonate ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Early Hydration ◽  
Cement Pastes ◽  
Calcium Sulfoaluminate ◽  
Lithium Compounds ◽  
Different Content ◽  
Cement Mixtures

This work investigated the influence of three different lithium compounds, lithium carbonate (Li2CO3), lithium sulfate (Li2SO4) and lithium chloride (LiCl), on the hydration and mechanical properties of calcium sulfoaluminate (CSA) cement mixtures. Five concentrations of Li+, 0, 0.05, 0.11, 0.16 and 0.22 mmol/g of cement, were chosen, and then the proportions (by mass) of three lithium compounds were determined. Compressive strengths at 8 h, 24 h and 28 days were tested. Meanwhile, an early hydration heat test, thermogravimetric (TG) analysis, X-ray diffraction (XRD) and scanning electron microscope (SEM) techniques were performed to study the influences of different lithium compounds on properties of CSA cement mixtures. The experimental results show that three lithium compounds can all accelerate the early hydration process of CSA cement. There is not a remarkable difference on the properties of CSA cement pastes with a different content of Li+. The anion of lithium compounds can also affect the properties of CSA cement pastes, the accelerating effects of LiCl and Li2SO4 are more significant than that of Li2CO3, but there is not a distinct difference between LiCl and Li2SO4.

Influence of Nano-SiO2 and Nano-TiO2 on Early Hydration of Calcium Sulfoaluminate Cement

2014 ◽  
Vol 599 ◽  
pp. 39-45 ◽  
Author(s):  
Bao Guo Ma ◽  
Hai Nan Li ◽  
Yan Chao Zhu ◽  
Lei Han ◽  
Xiang Guo Li
Keyword(s):  
Isothermal Calorimetry ◽  
Sem Analysis ◽  
Cement Stone ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Early Hydration ◽  
Cement Pastes ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
The Difference

Calcium sulfoaluminate (CSA) cements were currently receiving a lot of attention because their manufacture produced less CO2 than ordinary Portland cement (OPC). However, it was essential to understand all parameters which might affect the hydration process. This work dealt with the effect of two nanostructured materials, such as nanoSiO2 (NS) and nanoTiO2 (NT), on the properties of CSA pastes during early hydration. Isothermal calorimetry, X-ray diffraction (XRD) and Scanning electron microscopy (SEM) were used to analyze the pastes. Results indicated that the influence of NS and NT on the early hydration of CSA showed different: when NS and NT were added by 5% (mass fraction), the early hydration of CSA cement can be significantly promoted by NS, and slightly accelerated by NT. X-ray diffraction and SEM analysis results showed that both of NS and NT can improve the microstructure of the cement pastes, which made the cement stone more uniform and dense. For the difference, during cement hydration, except for nucleation function, NS had a high pozzolanic activity. Whereas,the effect of NT on microstructure of hardened CSA-cement was mainly due to its seeding effect.

scholarly journals Influence of Fly Ash on Mechanical Properties and Hydration of Calcium Sulfoaluminate-Activated Supersulfated Cement

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2514
Author(s):  
Zhengning Sun ◽  
Jian Zhou ◽  
Qiulin Qi ◽  
Hui Li ◽  
Na Zhang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Flexural Strength ◽  
Heat Evolution ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Granulated Blast Furnace Slag ◽  
Compressive And Flexural Strengths

This paper aimed to report the effects of fly ash (FA) on the mechanical properties and hydration of calcium sulfoaluminate-activated supersulfated cement (CSA-SSC). The CSA-SSC comprises of 80% granulated blast furnace slag (GBFS), 15% anhydrite, and 5% high-belite calcium sulfoaluminate cement (HB-CSA) clinker. The hydration products of CSA-SSC with or without FA were investigated by X-ray diffraction and thermogravimetric analysis. The experimental results indicated that the addition of FA by 10% to 30% resulted in a decrease in the rate of heat evolution and total heat evolution of CSA-SSC. As the content of FA was increased in the CSA-SSC system, the compressive and flexural strengths of the CSA-SSC with FA after 1 day of hydration were decreased. After 7 days of hydration, the compressive and flexural strength of CSA-SSC mixed with 10 wt.% and 20 wt.% of FA rapidly increased and exceeded that of ordinary Portland cement (OPC), especially the flexural strength. Moreover, the compressive strength of CSA-SSC mixed with 30 wt.% of FA after 90 days of hydration was close to that of OPC, and flexural strength of CSA-SSC mixed with 30 wt.% of FA after 7 days of hydration was close to that of OPC. The hydration products of the CSA-SSC and CSA-SSC mixed with FA were mainly ettringite and calcium silicate hydrate (C-S-H).

scholarly journals Strength Performance and Microstructure of Calcium Sulfoaluminate Cement-Stabilized Soft Soil

2021 ◽  
Vol 13 (4) ◽  
pp. 2295
Author(s):  
Hailong Liu ◽  
Jiuye Zhao ◽  
Yu Wang ◽  
Nangai Yi ◽  
Chunyi Cui
Keyword(s):  
Soft Soil ◽  
Hydration Product ◽  
X Ray Diffraction ◽  
Calcium Sulfoaluminate Cement ◽  
Strength Performance ◽  
X Ray ◽  
Calcium Sulfoaluminate ◽  
Stabilized Soil ◽  
Calcium Silicates ◽  
Hydrated Calcium

Calcium sulfoaluminate cement (CSA) was used to stabilize a type of marine soft soil in Dalian China. Unconfined compressive strength (UCS) of CSA-stabilized soil was tested and compared to ordinary Portland cement (OPC); meanwhile the influence of amounts of gypsum in CSA and cement contents in stabilized soils on the strength of stabilized soils were investigated. X-ray diffraction (XRD) tests were employed to detect generated hydration products, and scanning electron microscopy (SEM) was conducted to analyze microstructures of CSA-stabilized soils. The results showed that UCS of CSA-stabilized soils at 1, 3, and 28 d firstly increased and then decreased with contents of gypsum increasing from 0 to 40 wt.%, and CSA-stabilized soils exhibited the highest UCS when the content of gypsum equaled 25 wt.%. When the mixing amounts of OPC and CSA were the same, CSA-stabilized soils had a significantly higher early strength (1 and 3 d) than OPC. For CSA-stabilized soil with 0 wt.% gypsum, monosulfate (AFm) was detected as a major hydration product. As for CSA-stabilized soil with certain amounts of gypsum, the intensity of ettringite (Aft) was significantly higher than that in the sample hydrating without gypsum, but a tiny peak of AFm also could be detected in the sample with 15 wt.% gypsum at 28 d. Additionally, the intensity of AFt increased with the contents of gypsum increasing from 0 to 25 wt.%. When contents of gypsum increased from 25 to 40 wt.%, the intensity of AFt tended to decrease slightly, and residual gypsum could be detected in the sample with 40 wt.% gypsum at 28 d. In the microstructure of OPC-stabilized soils, hexagonal plate-shaped calcium hydroxide (CH) constituted skeleton structures, and clusters of hydrated calcium silicates (C-S-H) gel adhered to particles of soils. In the microstructure of CSA-stabilized soils, AFt constituted skeleton structures, and the crystalline sizes of ettringite increased with contents of gypsum increasing; meanwhile, clusters of the aluminum hydroxide (AH3) phase could be observed to adhere to particles of soils and strengthen the interaction.

Investigation on the Effect of Hydroxyapatite Nanorod on Cement Hydration and Strength Development

2021 ◽  
Vol 21 (3) ◽  
pp. 1578-1589
Author(s):  
Han Yan ◽  
Qianping Ran ◽  
Yong Yang ◽  
Xin Shu ◽  
Qian Zhang ◽  
...  
Keyword(s):  
Isothermal Calorimetry ◽  
Superior Performance ◽  
Strength Development ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
Cement Pastes ◽  
Supplementary Cementitious Material ◽  
Acceleration Period

This work investigated the effect of hydroxyapatite (HA) nanorods on the strength development and hydration of cement. Undispersed HA nanorods (HA-UD) and dispersed HA nanorods (HA-DN) were prepared by atom-efficient neutralization. The strength of mortars modified by HA nanorods was tested, as well as their compatibility with supplementary cementitious material. The hydration of HA-modified cement pastes was characterized via in situ X-ray diffraction, isothermal calorimetry and scanning electron microscopy. As the results suggest, the undispersed HA-DN caused a considerable increase in superplasticizer demand to achieve the same level of flow. Both HA nanorods showed a significant accelerating effect on early hydration, with approximately 100% strength enhancement at 12 h at 2.0% dosage. The effect on early strength of the nanorods is retained in systems with up to 30% fly ash in the binder mass. According to the characterizations, the rate of the hydration reaction in the acceleration period was enhanced by HA nanorods, and C3S consumption was also increased. In all of the testing situations, HA-DN showed superior performance, likely due to improved spatial distribution of the hydroxyapatites. The results suggest that proper dispersion of the nanorods is necessary to optimize its performance.

Hydration Behavior of Metakaolin-Cement Pastes with Different Contents of Reactive Aluminous at Early Age

2010 ◽  
Vol 150-151 ◽  
pp. 419-424
Author(s):  
Tao Sun ◽  
Zhong He Shui ◽  
Gui Ming Wang
Keyword(s):  
Early Period ◽  
Xrd Analysis ◽  
Insoluble Residue ◽  
Early Age ◽  
X Ray Diffraction ◽  
Early Hydration ◽  
Cement Pastes ◽  
Reaction Velocity ◽  
X Ray ◽  
Reactive Silica

What kind of role do the reactive aluminous has played during early hydration process of metakaolin-cement paste is investigated in present study. Therefore, metakaolin(MK) samples containing 45.94%, 22.86%, 0% reactive aluminous are prepared, respectively. In addition, X-ray Diffraction (XRD) analysis is employed to identify the crystalline phases of all specimens. The amount of acid-insoluble residue (AIR) of all specimens is used to evaluate the unreacted materials. The results obtained indicate that reactive aluminous can promote development of the early period strength significantly. Reactive silica and reactive aluminous reaction velocity was very slow during the first three days, then increased. The reaction velocity of reactive aluminous was faster than reactive silica between the first day and third day, but it shows an opposite result between the third day and seventh day.

scholarly journals Effect of Iron Phase on Calcination and Properties of Barium Calcium Sulfoaluminate Cement

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5813
Author(s):  
Jun Chang ◽  
Jixin Zhang ◽  
Yanchen Yuan ◽  
Kai Cui
Keyword(s):  
Compressive Strength ◽  
Liquid Phase ◽  
Eutectic Point ◽  
Material System ◽  
Phase Content ◽  
Calcium Sulfoaluminate Cement ◽  
Early Hydration ◽  
Calcium Sulfoaluminate ◽  
Eds Analysis ◽  
Iron Phase

In this paper, the effect of iron phase content on the calcination and properties of clinker and barium calcium sulfoaluminate cement was studied. The compressive strength of the samples was tested and combined with an XRD and SEM-EDS analysis, and the microstructure and composition of the barium calcium sulfoaluminate clinker and hydrated samples were characterized. The results showed that the oval-shaped particles were C2S minerals, and the hexagonal plate-shaped or rhombohedral dodecahedral particles were C2.75B1.25A3S¯. The Ba element was mainly distributed in the barium calcium sulfoaluminate region, and some of it was dissolved in C2S; the Fe element was distributed between C2.75B1.25A3S¯ and C2S crystal grains in the form of an iron phase solid solution, which acted as a solvent. When the iron phase composition was C4AF and the iron phase content was 5%, the early hydration and later strength were better, and the compressive strength after curing for 1, 3 and 28 days was 73.2 MPa, 97.9 MPa and 106.9 MPa, respectively. A proper amount of the iron phase can reduce the eutectic point of the sintered mature material system, increase the amount of liquid phase, reduce the viscosity of the liquid phase, effectively accelerate the migration of mineral ions and promote the formation and growth of minerals.

Effect of Calcium Sulfate on the Formation of Ettringite in Calcium Aluminate and Sulfoaluminate Blended Systems

2014 ◽  
Vol 599 ◽  
pp. 23-28 ◽  
Author(s):  
Ling Lin Xu ◽  
Pei Ming Wang ◽  
Guang Ming Wu ◽  
Guo Fang Zhang
Keyword(s):  
Calcium Aluminate ◽  
Calcium Sulfate ◽  
Ternary Systems ◽  
Environmental Scanning ◽  
X Ray Diffraction ◽  
Hydration Kinetics ◽  
Early Hydration ◽  
Free Expansion ◽  
Different Content ◽  
Electronic Microscope

The formation of ettringite and the expansion associated with it were studied on paste made from Portland cement, two Al-bearing compounds such as calcium aluminate cement and calcium sulphoaluminate cement, and calcium sulfate with different reactivities (anhydrite, α-hemihydrate and gypsum). The hydration process and formation of ettringite in the binders with different content of calcium sulfate was investigated by free expansion testing, isothermal conduction calorimetry, X-ray diffraction (XRD) and environmental scanning electronic microscope (ESEM). Results showed that the reactivity and amount of the calcium sulfate determined the balance between the hydration products of ettringite and monosulfate, and also the early hydration kinetics including the formation content, size and location of ettringite. It was also found that all the ternary systems with higher addition of calcium sulfate expand significantly. When a higher content of α-hemihydrate was added, besides ettringite much secondary gypsum also forms in voids between cement granules, which exerted adverse effects on the properties of ternary systems. However, the formation content of ettringite appeared to have no connection with the expansion value.

Utilization of CFB Fly Ash in Eco-Cement: Mechanical Properties and Microstructural Analysis

2010 ◽  
Vol 150-151 ◽  
pp. 885-889 ◽  
Author(s):  
Xiao Ming Liu ◽  
Yu Li ◽  
Ling Ling Zhang ◽  
Da Qing Cang
Keyword(s):  
Mechanical Properties ◽  
Fly Ash ◽  
Circulating Fluidized Bed ◽  
Microstructural Analysis ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Cement Pastes ◽  
X Ray ◽  
Xrd Techniques ◽  
Furnace Slag

The disposal of circulating fluidized bed (CFB) fly ash has been a serious environmental problem in the development of our society. In this work, the feasibility of recycling CFB fly ash as a blended material incorporating blast furnace slag (BFS), clinker and gypsum for the preparation of Eco-cement has been investigated. The mechanical properties of CFB fly ash based Eco-cements, including CFB fly ash–clinker system, CFB fly ash–ground BFS system, and CFB fly ash–ground BFS–clinker system, were evaluated in this paper. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques were used to analyze the microstructural changes and the hydration products of the CFB fly ash based Eco-cement pastes. The results indicated that it is feasible to use CFB fly ash along with BFS and clinker to produce Eco-cement. The hydration products of CFB fly ash based Eco-cement are mostly ettringite and amorphous C-S-H gel, which are principally responsible for the strength and structure development of CFB fly ash based Eco-cement in the hydration process.

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