Frost resistance of recycled concrete

Qin, Yawei; Shouchang, Deng; Zhang, Xuebing

doi:10.1007/s11771-007-0294-7

Cited by 6 publications

(5 citation statements)

References 3 publications

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“…Therefore, frost resistance becomes one of the most important durability characteristics for concrete structures in these regions. In such environment, water that penetrates the concrete and undergoes freezing and melting to generate expansion pressure, which escalates the quantity of internal cracks and voids within the concrete, thus reducing its durability [12,13]. With the influence of recurrent freeze-thaw cycles, the structure of buildings in cold regions transitions from compact to porous, markedly reducing the buildings' service life.…”

Section: Introductionmentioning

confidence: 99%

Potential for Recycling Metakaolin-Slag Based Geopolymer Concrete of Various Strength Levels in Freeze-Thaw Conditions

Liu,

Hua

et al. 2024

Preprint

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Geopolymer concrete (GPC) represents an innovative green and low-carbon construction material, offering a viable alternative to ordinary Portland cement concrete in building applications. However, existing studies tend to overlook the recyclability aspect of GPC for future use. Various structural applications necessitate the use of concrete with distinct strength characteristics. The recyclability of the parent concrete is influenced by these varying strengths. This study examined the recycling potential of GPC across a spectrum of strength grades (40, 60, 80 and 100 MPa, marked as C40, C60, C80 and C100) when subjected to freeze-thaw conditions. The cementitious material comprised 60% metakaolin and 40% slag, with natural gravel serving as the coarse aggregate, and the alkali activator consisting of sodium hydroxide solution and sodium silicate solution. The strength of the GPC was modulated by altering the Na/Al ratio. After 350 freeze-thaw cycles, the GPC specimens underwent crushing, washing, and sieving to produce recycled geopolymer aggregates (RGAs). Subsequently, their physical properties and microstructure were thoroughly examined. The findings indicated that GPC with strength grades of C100, C80, and C60 were capable of enduring 350 freeze-thaw cycles, in contrast to C40, which did not withstand these conditions. RGAs derived from GPC of strength grades C100 and C80 complied with the criteria for Class II recycled aggregates, whereas RGAs produced from GPC of strength grade C60 aligned with the Class III level. A higher strength grade in the parent concrete correlated with enhanced performance characteristics in the resulting recycled aggregates.

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Section: Introductionmentioning

confidence: 99%

Potential for Recycling Metakaolin-Slag Based Geopolymer Concrete of Various Strength Levels in Freeze-Thaw Conditions

Liu,

Hua

et al. 2024

Preprint

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“…Therefore, frost resistance becomes one of the most important durability characteristics for concrete structures in these regions [14]. In such an environment, concrete constructions have a longer setting time, slower strength development, and a reduced dehydration rate [15], as well as water that penetrates the concrete and undergoes freezing and melting to generate expansion pressure, which escalates the quantity of internal cracks and voids within the concrete, thus reducing its durability [16,17]. With the influence of recurrent freeze-thaw cycles, the structure of buildings in cold regions transitions from compact to porous, markedly reducing the buildings' service life.…”

Section: Introductionmentioning

confidence: 99%

Potential for Recycling Metakaolin/Slag-Based Geopolymer Concrete of Various Strength Levels in Freeze–Thaw Conditions

Liu,

Hua

et al. 2024

Materials

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Geopolymer concrete (GPC) represents an innovative green and low-carbon construction material, offering a viable alternative to ordinary Portland cement concrete (OPC) in building applications. However, existing studies tend to overlook the recyclability aspect of GPC for future use. Various structural applications necessitate the use of concrete with distinct strength characteristics. The recyclability of the parent concrete is influenced by these varying strengths. This study examined the recycling potential of GPC across a spectrum of strength grades (40, 60, 80, and 100 MPa, marked as C40, C60, C80, and C100) when subjected to freeze–thaw conditions. Recycling 5–16 mm recycled geopolymer coarse aggregate (RGAs) from GPC prepared from 5 to 16 mm natural coarse aggregates (NAs). The cementitious material comprised 60% metakaolin and 40% slag, with natural gravel serving as the NAs, and the alkali activator consisting of sodium hydroxide solution and sodium silicate solution. The strength of the GPC was modulated by altering the Na/Al ratio. After 350 freeze–thaw cycles, the GPC specimens underwent crushing, washing, and sieving to produce RGAs. Subsequently, their physical properties (apparent density, water absorption, crushing index, and attached mortar content and microstructure (microhardness, SEM, and XRD) were thoroughly examined. The findings indicated that GPC with strength grades of C100, C80, and C60 were capable of enduring 350 freeze–thaw cycles, in contrast to C40, which did not withstand these conditions. RGAs derived from GPC of strength grades C100 and C80 complied with the criteria for Class II recycled aggregates, whereas RGAs produced from GPC of strength grade C60 aligned with the Class III level. A higher-strength grade in the parent concrete correlated with enhanced performance characteristics in the resulting recycled aggregates.

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“…When the method is used to detect buried objects, such as underground cavities, pipes, artificial structure, etc.,the research based on layered model is unsuitable because of the heterogeneity of media. Therefore, the numerical method is used to study the propagation characteristics of Rayleigh waves in inhomogeneous media [3,4,5,6]. But the studies are mainly focused on artificial boundary condition of numerical simulation and wave field features and dispersion characteristics of layered media.…”

Section: Introductionmentioning

confidence: 99%

“…But the studies are mainly focused on artificial boundary condition of numerical simulation and wave field features and dispersion characteristics of layered media. For examples, high-order staggered grid finite difference method and PML absorbtion boundary conditions are used to model elastic wave field of homogeneous and layered media, which attenuates the boundary reflection effectively and studies the dispersion characteristics of media contained weak interlayer successfully [4]. But the case of media with buried objects are not concerned.…”

Section: Introductionmentioning

confidence: 99%

Study on Characteristics of Rayleigh Waves in Media Containing Shallow Rectangular Cavities

Feng

Yong

2014

AMM

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Numerical simulations of Rayleigh wave with a source on the free surface are achieved by using FEM(finite element method). Artificial viscous boundary conditions are used to weaken boundary reflections. Modeling results are proved by comparison between analytic and numerical solutions in homogeneous half-space and layered media. Surface wave field of homogeneous half-space with rectangular cavities are modeled and analyzed. The results show that the velocity of converted wave above cavity is less than which in homogeneous media and energy is concentrated obviously in the area when the depth of cavity is relatively smaller than surface wave length. The cavity can be located by characteristics in time domain and frequency domain of surface wave. Dispersion characteristics of waves above cavity are mainly influenced by the top depth of the cavity instead of bottom depth and consistent with Lamb wave of slab with corresponding height and same media.

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Frost resistance of recycled concrete

Cited by 6 publications

References 3 publications

Potential for Recycling Metakaolin-Slag Based Geopolymer Concrete of Various Strength Levels in Freeze-Thaw Conditions

Potential for Recycling Metakaolin-Slag Based Geopolymer Concrete of Various Strength Levels in Freeze-Thaw Conditions

Potential for Recycling Metakaolin/Slag-Based Geopolymer Concrete of Various Strength Levels in Freeze–Thaw Conditions

Study on Characteristics of Rayleigh Waves in Media Containing Shallow Rectangular Cavities

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