scholarly journals Influence of Nano-Barium Sulfate Agglomeration on Microstructure and Properties of the Hardened Cement-Based Materials

2015 ◽  
Vol 03 (11) ◽  
pp. 72-81
Author(s):  
Mohamed El-Shahate Ismaiel Saraya ◽  
Inas Mostafa Bakr
Keyword(s):  
Barium Sulfate ◽  
Hardened Cement ◽  
Microstructure And Properties ◽  
Cement Based Materials

Effect of ion chelator on microstructure and properties of cement-based materials under sulfate dry-wet cycle attack

2020 ◽  
Vol 257 ◽  
pp. 119527
Author(s):  
Peng He ◽  
Jianying Yu ◽  
Yang Wan ◽  
Ruiyang Wang ◽  
Xiaobin Han ◽  
...  
Keyword(s):  
Microstructure And Properties ◽  
Cement Based Materials

scholarly journals Review of Carbonation Resistance in Hydrated Cement Based Materials

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Joseph Mwiti Marangu ◽  
Joseph Karanja Thiong’o ◽  
Jackson Muthengia Wachira
Keyword(s):  
Environmental Benefits ◽  
Partial Substitution ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Hydrated Cement ◽  
Blended Cements ◽  
Carbonation Process ◽  
Carbonation Resistance ◽  
Cement Based Materials ◽  
Process Factors

Blended cements are preferred to Ordinary Portland Cement (OPC) in construction industry due to costs and technological and environmental benefits associated with them. Prevalence of significant quantities of carbon dioxide (CO2) in the atmosphere due to increased industrial emission is deleterious to hydrated cement materials due to carbonation. Recent research has shown that blended cements are more susceptible to degradation due to carbonation than OPC. The ingress of CO2 within the porous mortar matrix is a diffusion controlled process. Subsequent chemical reaction between CO2 and cement hydration products (mostly calcium hydroxide [CH] and calcium silicate hydrate [CSH]) results in degradation of cement based materials. CH offers the buffering capacity against carbonation in hydrated cements. Partial substitution of OPC with pozzolanic materials however decreases the amount of CH in hydrated blended cements. Therefore, low amounts of CH in hydrated blended cements make them more susceptible to degradation as a result of carbonation compared to OPC. The magnitude of carbonation affects the service life of cement based structures significantly. It is therefore apparent that sufficient attention is given to carbonation process in order to ensure resilient cementitious structures. In this paper, an indepth review of the recent advances on carbonation process, factors affecting carbonation resistance, and the effects of carbonation on hardened cement materials have been discussed. In conclusion, carbonation process is influenced by internal and external factors, and it has also been found to have both beneficial and deleterious effects on hardened cement matrix.

Macro-Defect-Free Cement: A Review

1989 ◽  
Vol 179 ◽  
Author(s):  
J. Francis Young
Keyword(s):  
Cement Paste ◽  
Casting Process ◽  
Particle Dispersion ◽  
Particle Packing ◽  
Hardened Cement ◽  
High Porosity ◽  
Hardened Cement Paste ◽  
Water Requirements ◽  
Wide Range ◽  
Cement Based Materials

Cement-based materials have been traditionally formed by casting. The amount of water used in the casting process determines the porosity of the hardened material. The water requirements, and the tendency for cement grains to agglomerate, result in hardened cement paste having high porosity and a wide range of pore sizes. Consequently, such materials are not very strong and contain critical flaws whose dimensions are of the order of 0.1 mm. Although improvements in particle packing and particle dispersion to reduce porosity have resulted in significant increases in strength, such materials are still very brittle and have relatively low tensile and flexural strengths.

The Thermal Deformation of Cement-Based Material at Low Temperatures

2014 ◽  
Vol 1081 ◽  
pp. 279-283 ◽  
Author(s):  
Nan Zhang ◽  
Juan Liao ◽  
Tao Zhang ◽  
Wen Zhan Ji
Keyword(s):  
Low Temperature ◽  
Cement Paste ◽  
Low Temperatures ◽  
Thermal Deformation ◽  
Pore Solution ◽  
Freezing Point ◽  
Bulk Solution ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Cement Based Materials

Thermal deformation of concrete at low temperature expands from-20°C to-50°C and contracts from-30°C to-10°C. Based on previous studies, the paper tries to explain the deformaion trend by analyzing freezing point of bulk solution and pore solution in saturated hardened cement paste. The result shows that it is critical to thermal deformation of cement-based materials at low temperature that pore solution in the pores smaller than 8 nm freezes.

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