Stress relaxation properties of calcium silicate hydrate: a molecular dynamics study

The heat of hydration, mechanical properties, pozzolanic activity, and microscopic characteristics of cement pastes incorporating co-combusted fly ash (CCFA) were investigated, and the disparities between the CCFA/cement system and the coal fly ash (CFA) binding system were also compared. The results indicate a decrease in the heat of hydration for both CFA and CCFA samples, with a more pronounced trend observed as the fly ash content increased from 10% to 30%. The distinction in the early hydration between CFA and CCFA samples primarily manifested in the rate of heat release, potentially correlated with variations in the active Al2O3 content in the fly ash. Neither CFA nor CCFA samples exhibited significant cementitious activity at 3 days, functioning solely as inert fillers in the cement paste. By 3 and 28 days, the mechanical properties of both CFA and CCFA samples were inferior to those of pure cement paste. However, by 180 days of hydration, the compressive strength of CCFA-blended mortar notably increased, with the highest strength observed in the 10% CCFA-blended sample. Both CFA and CCFA samples produced the secondary hydration product C-A-S-H and demonstrated comparable consumption of calcium hydroxide (CH). These findings underscore the potential of CCFA as a supplementary cementitious material (SCM) and lay a foundation for its widespread adoption.

Section: Sem-eds Analysismentioning

confidence: 91%

Section: Sem-eds Analysismentioning

confidence: 96%

Investigating the Hydration, Mechanical Properties, and Pozzolanic Activity of Cement Paste Containing Co-Combustion Fly Ash

Ding,

Du,

et al. 2024

“…The hydration process of OPC results mainly in a calcium silicate hydrate gel (C-S-H) responsible for the time-dependent viscoelastic response to applied deformation [144], impacting the mechanical properties and durability of cement-based materials [145]. On the other hand, geopolymer cement is a binder produced by the alkali-activation of aluminosilicates such as fly ash/rice husk ash, silica fume, clay, metakaolin, GGBS, etc.…”

Section: Alternative Binders-a More Sustainable Approachmentioning

confidence: 99%

Building a Greener Future: Advancing Concrete Production Sustainability and the Thermal Properties of 3D-Printed Mortars

Capêto,

Jesus,

Uribe

et al. 2024

The integration of waste materials in extrudable cement mixtures has the potential to make the construction industry more sustainable by reducing carbon footprints and developing eco-friendly materials. This along with advancements in 3D concrete printing (3DCP) provides engineering and architectural benefits by reducing material waste and costs. In this paper, the impact of waste incorporation on properties of mortar and concrete is examined. The use of waste materials, such as pumice, coal slag, agricultural lignocellulosic residues, and recycled rubber tyres, to improve thermal insulation and durability of cementitious composites is discussed. In addition, the incorporation of air-entraining admixtures with surfactant activity is explored for their indirect effect on thermal behaviour, pore size reduction, and enhancement in concrete properties. This review includes important topics such as a strength resistance to freezing and thawing, fire resistance, plasticising effect, and delay in cement hydration. These findings highlight the benefits of using diverse waste materials in construction, providing a multidimensional approach to waste management, cost optimization, and enhanced construction materials in the context of 3DCP.

“…It is well known that hydration is one of the key processes to increase the strength of mortar, which requires an appropriate amount of water. The strength, volume stability and durability can be improved by maintaining optimal moisture content in the mortar substrate [38]. Neville [37] found that the hydration reaction nearly stops when the relative humidity inside the cement sample drops below 80%, so it is important to maintain proper moisture conditions during the curing process.…”

Section: Influence Of Curing Age and Water-cement Ratio On The Bondin...mentioning

confidence: 99%

Effect of Thermal Cycles and Curing Age on Bonding Strength of Cement Mortar Using Manufactured Sand

Cui,

Peng,

Yang

et al. 2024

The bonding of cement mortar to the concrete substrate is crucial in buildings. In this study, cement mortar was prepared using manufactured sand (MS) instead of river sand (RS). The bonding strength between manufactured sand mortar (MSM) and concrete substrate was evaluated and the effects of curing age, water-to-cement ratio (w/c) and thermal cycling on the bonding strength were discussed and compared with those of the river sand mortar (RSM). The compressive strength of the MSM was consistently higher than that of the RSM, while the bonding strength of RSM was consistently higher than that of MSM, indicating that the bonding strength does not depend on the compressive strength of the mortar. As the number of thermal cycles increased, the pull-off strengths at the interface between the concrete and MSM or RSM at different w/c ratios all decreased, and the RSM experienced a larger reduction. After 400 cycles, the percentage decrease in bonding strength of MSM sample ranged from 18.62% to 30.86%.