Properties and mechanisms of brick-concrete recycled aggregate strengthened by compound modification treatment

He, Ziming; Wu, Hansong; Wang, Wenzhen; Wang, Lusheng; Guo, Yinchuan

doi:10.1016/j.conbuildmat.2021.125678

Cited by 33 publications

(8 citation statements)

References 40 publications

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“…Following the references [ 23 , 34 ], the DWA test was performed. Hydrostatic balance was used, and the water absorption at time t was calculated using Equations (3) and (4):

where w at is the water absorption of the RCA at time t , %; m t is the mass of the RCA immersed in water at time t , g; m s and m 24 are the masses of the RCA immersed in water at time t = 0 and t = 24 h, g, respectively.…”

Section: Materials and Methodologymentioning

confidence: 99%

“…In order to improve the properties of RCA, various treatment methods have been attempted. At present, there are mainly three approaches: (a) eliminate the old mortar by grinding, heating grinding or acid solution et al [ 15 , 16 , 17 , 18 , 19 ]; (b) strengthen the old mortar with CO 2 , sodium silicate or nano materials et al [ 1 , 20 , 21 , 22 , 23 , 24 , 25 ]; (c) coat the surface by immersing RCA in cement-based slurries such as cement, fly ash and silica fume et al [ 26 , 27 , 28 , 29 , 30 ]. All the above approaches can improve the properties of RCA to a certain extent.…”

Section: Introductionmentioning

confidence: 99%

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Influences of Efficient Spraying of Cement-Based Slurries on Recycled Coarse Aggregate

Yin

Kang

et al. 2022

Materials

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The inferior property is usually one of the major problems of recycled coarse aggregate (RCA), and the utilization of the RCA is limited. Strengthening the RCA is being widely explored. Immersing the RCA in the cement-based slurry is an effective approach. However, lots of slurry and time are required, and it is difficult to integrate the immersing method into the production line of the RCA. In this paper, a circular spraying method was proposed to treat the RCA using cement-based slurry. The immersing method was also conducted to verify the feasibility of the spraying method. The crushing value (CV), 24 h water absorption (WA), apparent density (AD) and dynamic water absorption (DWA) were tested, and the micro-morphology was also observed to explore the strengthening mechanism. Results showed that the CV and the WA decreased by up to 30.0% and 14.3% when the spraying method was used. The AD was slightly influenced by the cement-based slurry regardless of the treatment method. Considering the CV, WA and AD, the comprehensive grade of the RCA could be enhanced from III to II by using the spraying method. It was worth noting that the effects of the spraying method and the immersing method were basically equivalent. When the spraying method was adopted, only about 1 min and a small amount of slurry (about 5% of the RCA mass) were required to treat the RCA.

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“…Following the references [ 23 , 34 ], the DWA test was performed. Hydrostatic balance was used, and the water absorption at time t was calculated using Equations (3) and (4):

Section: Materials and Methodologymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Influences of Efficient Spraying of Cement-Based Slurries on Recycled Coarse Aggregate

Yin

Kang

et al. 2022

Materials

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“…Thermal treatment was also used for this purpose [ 55 ], but high energy intake may be required to reach the desired decomposition temperatures (around 800 °C). Surface-treating RA before its application in concrete: He et al [ 56 ] found that the density, water absorption, and crushing index of RA were improved with previous treatment using pozzolan slurry combined with sodium silicate and silicon-based additives, improving its performance in concrete. Li et al [ 57 ] pre-treated RA with nanosilica suspension (spraying and soaking), observing that the micro-hardness of both the old mortar and the new mortar near the ITZ was enhanced after treatment, improving the compressive strength, water absorption, and chloride penetration resistance of RA-containing concrete.…”

Section: Challenges and Outlookmentioning

confidence: 99%

Recycled Aggregate: A Viable Solution for Sustainable Concrete Production

et al. 2022

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Construction and demolition activities consume large amounts of natural resources, generating 4.5 bi tons of solid waste/year, called construction and demolition waste (C&DW) and other wastes, such as ceramic, polyethylene terephthalate (PET), glass, and slag. Furthermore, around 32 bi tons of natural aggregate (NA) are extracted annually. In this scenario, replacing NA with recycled aggregate (RA) from C&DW and other wastes can mitigate environmental problems. We review the use of RA for concrete production and draw the main challenges and outlook. RA reduces concrete’s fresh and hardened performance compared to NA, but these reductions are often negligible when the replacement levels are kept up to 30%. Furthermore, we point out efficient strategies to mitigate these performance reductions. Efforts must be spent on improving the efficiency of RA processing and the international standardization of RA.

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“…Mazen et al [24] used the nano-ZnO to modify the interface of recycled aggregate concrete. He et al [25][26][27] used four different types of solutions to soak the brick-concrete recycled aggregate to improve the strength of the interface zone, and the results showed that the application performance of the brickconcrete recycled aggregate, after soaking in a water glass solution, was significantly improved in cement-based materials. Hu et al [28] used SCA to modify the interface of recycled aggregate.…”

Section: Introductionmentioning

confidence: 99%

Study on the Effect of Interfacial Modification on the Properties of Super Standard Mica Sand Cement-Based Materials

Liu,

Yang,

Jiang

et al. 2024

Buildings

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Mica is a harmful substance in sand and occurs frequently. The application of super standard mica sand is a difficult problem in large-scale engineering. In this work, the effects of an interface modifier, mineral admixture, and a curing system on the properties of cement-based materials with super standard mica sand were studied. The strength of cement-based materials linearly decreases with the mica content in sand. When the mica content in sand exceeds 6%, the compressive strength of mortar and concrete at 28 d decreases by more than 22.3% and 33.5%, respectively. By adding the silane coupling agent (SCA) of 50% mica mass and curing in natural conditions, the compressive strength of mortar increases by 10.9%. The cement-based materials with the SCA are more suitable for curing in natural conditions, and the performance of the SCA will not be affected by adding appropriate amounts of mineral admixture. The drying shrinkage strain of the concrete, with the sand containing high mica content modified by SCA, is reduced by 10.5%, and the diffusion of chloride ions in concrete is reduced. The XRD results show that the addition of the interfacial agent does not change the hydration products. The MIP and SEM results show that the SCA can form a bridge structure between the hydration products and the mica, improve the bonding strength of the interface zone, and reduce the number of harmful pores.

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Properties and mechanisms of brick-concrete recycled aggregate strengthened by compound modification treatment

Cited by 33 publications

References 40 publications

Influences of Efficient Spraying of Cement-Based Slurries on Recycled Coarse Aggregate

Influences of Efficient Spraying of Cement-Based Slurries on Recycled Coarse Aggregate

Recycled Aggregate: A Viable Solution for Sustainable Concrete Production

Study on the Effect of Interfacial Modification on the Properties of Super Standard Mica Sand Cement-Based Materials

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