Effect of clay content on shrinkage of cementitious materials

Zhao, Haixin; Ma, Yuefeng; Zhang, Jian; Hu, Zhaoyang; Li, Hua; Wang, Yujiang; Liu, Jiaping; Wang, Kangchen

doi:10.1016/j.conbuildmat.2021.125959

Cited by 12 publications

(4 citation statements)

References 61 publications

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“…These results show that the F6 and F7 sediments respond differently to desiccation compared to the other sediments because they show greater shrinkage for a similar amount of water loss. The study of Zhao et al [41] also showed that for similar mass loss, the pastes containing more clay show a higher drying shrinkage. 5 summarizes the effect of incorporating sediments as an addition to cement or as sand on the various studied properties.…”

Section: Drying Shrinkagementioning

confidence: 89%

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Reuse of Untreated Fine Sediments as Filler: Is It More Beneficial than Incorporating Them as Sand?

et al. 2022

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Large amounts of sediments are dredged each year to ensure navigation. These materials, classified as waste, seem to be promising alternatives to conventional construction materials. Dredging operations, carried out by the Territorial Directorate of the Seine Basin (DTBS), generate an annual volume of sediments of about 150,000 m3, of which nearly 50% are fine sediments (<80 μm). For these fine sediments, it is necessary to look for possible ways of valorisation, knowing that the coarse sediments, sands and gravels are already easily reused in concrete. The valorisation of fine sediments, such as concrete with 30% sand, has already been evaluated. However, it was found to significantly affect concrete performance; it extends setting time from 3 to 18 h, decreases compressive strength by an average of 50% and increases shrinkage deformation up to 200%. This paper seeks to evaluate the effects of ten different fine sediments, used as substitutes for 10% of cement by volume, on physico-chemical and mechanical properties. The experimental results show that fine sediments marginally affect concrete properties. The main peak of the released heat flux is delayed to less than 4 h, the compressive strength is decreased by 8% on average and the increase in shrinkage deformation does not exceed 17%, except for in two fine sediments. This incorporation method also has an environmental advantage over substituting 30% of concrete with sand, as it reduces CO2 emissions by almost 10% (instead of 0.2%).

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Section: Drying Shrinkagementioning

confidence: 89%

“…This results in an increase in swelling at an early age and in shrinkage afterward, due to drying [40]. The results of Zhao et al [41] also show that greater shrinkage occurs in specimens with higher clay content, and this trend was more pronounced at latter ages.…”

Section: Drying Shrinkagementioning

confidence: 99%

Reuse of Untreated Fine Sediments as Filler: Is It More Beneficial than Incorporating Them as Sand?

et al. 2022

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“…Consequently, the rate of breaking the Ca-O, Si-O-Si, and Al-O-Al bonds is sped up, which leads to the increase in Ca 2+ ion concentration and accelerates the formation of hydration products and the arrival of the initial setting state [20,46,47]. However, the water absorption of mud also delays the hydration process, especially with high kaolinite content [48][49][50][51], leading to a longer final setting time. As for the effect of the particle sizes of mud on setting time, the capability of liquid absorption of clay with a smaller particle size is stronger than that of silt with a larger particle size [46].…”

Section: Se Ing Timementioning

confidence: 99%

“…When the silt and clay content is less than 4%, the mud has almost no effect on the compressive and flexural strengths of AAS mortar, which is because the mud fills the pores of the sand skeleton [52] and reduces the negative effect caused by the addition of mud. When the mud content exceeds 4%, the compressive and flexural strengths of AAS mortar decrease rapidly, mainly for the following reasons: (1) mud absorbs water from the fresh mortar and this affects the hydration process [49][50][51];…”

Section: Mechanical Propertymentioning

confidence: 99%

Effects of Mud Content on the Setting Time and Mechanical Properties of Alkali-Activated Slag Mortar

Chen²,

Jia

et al. 2023

Materials

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High mud content in the sand has a negative impact on cement mortar but there is little research on Alkali-activated slag (AAS) mortar. In order to explore the impacts of mud content in the sand on the performance of AAS mortar, this paper used sand that contains silt, clay, and a mixture of silt and clay; tested the setting time of AAS with different mud contents of 0%, 2%, 4%, 6%, 8%, and 10%; and measured the unconfined compressive strength and beam flexural strength of 3 d, 7 d, and 28 d AAS mortar specimens. The microstructure of AAS mortar with different kinds of mud was observed by scanning electron microscope (SEM), the elemental composition of the hydration product was tested by energy dispersive spectroscopy (EDS), and the AAS interaction mechanism with different kinds of mud was analyzed. The main conclusions are: the higher the mud content in the sand, the shorter the initial setting time and the longer the final setting time of AAS, mainly because the mud in the sand affects the hydration process; mud content above 4% causes a rapid decrease in the compressive and flexural strengths of AAS mortar, mainly because the mud affects the hydration process and hinders the bonding of the hydration product with the sand. When there is no mud in the sand, the main hydration product of AAS is dense calcium-alumina-silicate-hydrate (C-A-S-H) gel. When the sand contains silt, the hydration product of AAS is loose C-A-S-H gel. When the sand contains clay, the hydration products of AAS contain C-A-S-H gel and a small amount of sodium-aluminum-silicate-hydrate (N-A-S-H), and needle-like crystals. Loose gel and crystals have a negative effect on the AAS mortar strength.

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Effect of clay content on plastic shrinkage cracking of cementitious materials

Zhao

Zhang

et al. 2022

Construction and Building Materials

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Effect of clay content on shrinkage of cementitious materials

Cited by 12 publications

References 61 publications

Reuse of Untreated Fine Sediments as Filler: Is It More Beneficial than Incorporating Them as Sand?

Reuse of Untreated Fine Sediments as Filler: Is It More Beneficial than Incorporating Them as Sand?

Effects of Mud Content on the Setting Time and Mechanical Properties of Alkali-Activated Slag Mortar

Effect of clay content on plastic shrinkage cracking of cementitious materials

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