Effect of Nanosilica Additions on Belite Cement Pastes Held in Sulfate Solutions

Physical, chemical and mechanical properties of high belite cement (HBC) blended with high pulverized fly ash (HPFA) with stable ratio of silica fume (SF) in comparison with Portland cement (OPC) were investigated. Results showed that the water of consistency and setting times (Initial and final) tended to increase with the increase of HPFA content. The bulk density and compressive strength were also improved and enhanced with the increase of HPFS content at all hydration times, but only up to 15 % HPFA, and then decreased with further increase. However, the total porosity slightly decreased, but started to increase with further increase of >15 % HPFA. The free lime content of the pure OPC and HBC gradually were increased as the hydration times progressed up to 90 days, while those of blended cements increased only up to 7 days and then decreased onward. The results were confirmed by measuring the heat of hydration and ultrasonic pulse velocity for the optimum cement pastes comparing with those of both OPC and HBC. The heat of hydration of the optimum cement pastes was decreased at all hydration times and become lower than those of OPC and HBC. The ultrasonic pulse velocity test (USPV) proved that the uniformity and quality of the matrix of the hardened cement pastes are good with no cracks.

Download Full-text

Impact of cation type and fly ash on deterioration process of high belite cement pastes exposed to sulfate attack

Construction and Building Materials ◽

10.1016/j.conbuildmat.2021.122961 ◽

2021 ◽

Vol 286 ◽

pp. 122961

Author(s):

Chunmeng Jiang ◽

Linhua Jiang ◽

Shuangxi Li ◽

Xinjun Tang ◽

Lei Zhang

Keyword(s):

Fly Ash ◽

Sulfate Attack ◽

Cement Pastes ◽

Deterioration Process ◽

Cation Type ◽

Belite Cement

Download Full-text

Phase development in conventional and active belite cement pastes by Rietveld analysis and chemical constraints

Cement and Concrete Research ◽

10.1016/j.cemconres.2009.06.017 ◽

2009 ◽

Vol 39 (10) ◽

pp. 833-842 ◽

Cited By ~ 36

Author(s):

Antonio J.M. Cuberos ◽

Ángeles G. De la Torre ◽

M. Carmen Martín-Sedeño ◽

Laureano Moreno-Real ◽

Marco Merlini ◽

...

Keyword(s):

Rietveld Analysis ◽

Cement Pastes ◽

Phase Development ◽

Belite Cement

Download Full-text

In situ observing the erosion process of cement pastes exposed to different sulfate solutions with X-ray computed tomography

Construction and Building Materials ◽

10.1016/j.conbuildmat.2018.05.093 ◽

2018 ◽

Vol 176 ◽

pp. 556-565 ◽

Cited By ~ 14

Author(s):

Yonggan Yang ◽

Yunsheng Zhang ◽

Wei She ◽

Naidong Liu ◽

Zhiyong Liu

Keyword(s):

Computed Tomography ◽

Erosion Process ◽

Cement Pastes ◽

X Ray ◽

Sulfate Solutions ◽

X Ray Computed

Download Full-text

Durability and chemical resistance of nanoparticles fly ash and silica fume belite cement pastes against sulfate and chloride aggressive media- Part II

NanoNEXT ◽

10.54392/nnxt2141 ◽

2021 ◽

Vol 2 (4) ◽

pp. 1-13

Author(s):

Darweesh H.H.M

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Silica Fume ◽

Chemical Resistance ◽

Sulfate Solution ◽

Chloride Ions ◽

Cement Pastes ◽

Total Chloride ◽

Total Sulfate ◽

Belite Cement

The durability (chemical resistence) of the Portland cement (OPC), belite cement (BC) and the optimum belite cement (B4), which their physical and chemo/mechanical properties were perviously investigated in Part I, against 4 % MgSO4 and 4% MgCl2 solutions up to 12 months in terms of compressive strength, total sulfate and total chloride was evaluated and studied. Results showed that the optimum belite cement (B4) containing 15 % High pulverized fly ash (HPFA) and 5 % Silica fume (SF) could be resisted up to 6 months, while that of BC could be withstood only up to 5 months, and the OPC could not resist more than three months of immersion in 4% MgSO4 solution. The compressive strength values exhibited by the samples immesed in sulfate solution at 3, 5 and 6 months of immersion were 83.81, 76.38 and 91.13 MPa, respectively. The same trend was displayed when the same samples were exposed to 4% MgCl2 solution. The compressive strength values exhibited by the same samples exposed to chloride solution at 3, 5 and 6 months of immersion were 84.49, 82.23 and 93.32 MPa, respectively. The total sulfate and chloride contents were enhanced with immesion time up to 12 months, but their values were the minimum with B4 and the maximum with OPC, while with BC were the medium. The optimum cement batch (B4) achieved the highest resistance where it recorded the lowest values for sulfate and chloride ions, but the OPC exhibited the lowest resistance where it recorded the highest values of sulfate and chloride contents at all immersion ages till 12 months.

Download Full-text

Properties and Mechanism of Hydration of Fly Ash Belite Cement Prepared from Low-Quality Fly Ash

Applied Sciences ◽

10.3390/app10207026 ◽

2020 ◽

Vol 10 (20) ◽

pp. 7026

Author(s):

Yongfan Gong ◽

Cong Liu ◽

Yanli Chen

Keyword(s):

Fly Ash ◽

Low Temperature ◽

Portland Cement ◽

Hydration Reaction ◽

Low Grade ◽

Early Hydration ◽

Cement Pastes ◽

Technological Support ◽

20 Nm ◽

Belite Cement

Fly ash belite cement (FABC) is predominantly composed of α′L-C2S and C12A7. It is prepared from low-grade fly ashes by hydrothermal synthesis and low-temperature calcination methods. The formation, evolution process, and microstructure of FABC hydration productions were studied in this work, and the ultimate aim is to give a theoretical foundation and technological support for the application of the new cementitious material made of low-quality fly ash. The results showed that the optimal amount of gypsum was about 7% of cement by weight. The 3-day and 28-day compressive strength of cement pastes with 7% gypsum was 13.6 and 60.2 MPa, respectively. Meanwhile, the 28-day flexural and compressive strengths of mortars with 7% gypsum were 4.6 and 25.9 MPa, respectively. The early hydration heat release rate of this low-temperature calcined cement was higher compared with that of high-temperature calcined cement as Portland cement. FABC hydration pastes contained mostly C-S-H, ettringite (AFt), unreacted mullite, and quartz. It was significantly different from Portland cement in that no calcium hydroxide [Ca(OH)2] was observed in the hydration products of different ages because all Ca(OH)2 formed in the hydration reaction could react completely to generate AFt. The ratio of harmful pores (d ≥ 50 nm) reached 55.04% after 3-day hydration. However, it decreased to 6.71%, which was lower than that of Portland cement pastes (35.72%) after 28-day hydration. In the later hydration period from 3 to 28 days, the strength developed rapidly, and a compact microstructure appeared in the hardened paste due to the presence of pores less than 20 nm in diameter.

Download Full-text