Effect of recycled fine aggregates on alkali-activated slag concrete properties

Huang, Jinguang; Zou, Chaoying; Yang, Bin; Yan, Jie

doi:10.1016/j.istruc.2020.12.064

Cited by 40 publications

(23 citation statements)

References 36 publications

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“…This reduction in strength could be associated with the weak interfacial bond between the aggregate and alkali-activated matrix as well as the rough porous nature of the RCA [93]. Analogous findings were reported in other work on alkali-activated fly ash and slag mortars and concrete incorporating recycled aggregates [28,[40][41][42][43][44][45][46][47]]. Yet, this negative impact of RCA was less pronounced at a later age, possibly due to a stronger matrix attributed to the late reaction of fly ash, as reported in the literature [94].…”

Section: Effect Of Rca Replacementsupporting

confidence: 77%

“…Indeed, the performance of alkali-activated concrete incorporating RCA has been investigated in the literature. Inferior mechanical and durability characteristics were reported for RCAbased alkali-activated concrete compared to the NA-based counterparts, owing to the poor properties of RCA relative to those of NA [40][41][42][43][44][45][46][47]. Such findings hinder its adoption by the construction industry.…”

Section: Introductionmentioning

confidence: 99%

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Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand

et al. 2021

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This study evaluates the performance of alkali-activated slag-fly ash blended concrete made with recycled concrete aggregates (RCA) and reinforced with steel fibers. Two blends of concrete with ground granulated blast furnace slag-to-fly ash ratios of 3:1 and 1:1 were used. Natural aggregates were substituted with RCA, while macro steel fibers with 35 mm of length and aspect ratio of 65 were incorporated in RCA-based mixtures at various volume fractions. Fine aggregates were in the form of desert dune sand. Mechanical and durability characteristics were investigated. Experimental results revealed that RCA replacement decreased the compressive strength of plain concrete mixtures with more pronounced reductions being perceived at higher replacement percentages. Mixtures made with 30%, 70%, and 100% RCA could be produced with limited loss in the design compressive strength upon incorporating 1%, 2%, and 2% steel fibers, by volume, respectively. In turn, splitting tensile strength was comparable to the NA-based control while adding at least 1% steel fiber, by volume. Moreover, higher water absorption and capillary sorptivity and lower ultrasonic pulse velocity, bulk resistivity, and abrasion resistance were reported during RCA replacement. Meanwhile, incorporation of steel fibers densified the concrete and enhanced its resistance to abrasive forces, water permeation, and water transport. Analytical regression models were developed to correlate hardened concrete properties to the 28-day cylinder compressive strength.

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Section: Effect Of Rca Replacementsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand

et al. 2021

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“…This is because the addition of RA improves the grain gradation of concrete [77]. Furthermore, some unreacted cement particles may also adhere to the RA, thereby increasing the cementitious material content in the mixture [78]. This phenomenon is very rare.…”

Section: Influence Of Ra Quality On Compressive Strength Of Racmentioning

confidence: 99%

Effect of Recycled Aggregate and Slag as Substitutes for Natural Aggregate and Cement on the Properties of Concrete: A Review

Zhang¹,

Wang²,

Zheng³

et al. 2023

Journal of Renewable Materials

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Using recycled aggregate (RA) and slag instead of natural aggregate (NA) and cement can reduce greenhouse gas emissions (GHGE) and achieve effective waste recovery. In recent years, RA has been widely used to replace NA in concrete. Every year, several researchers conduct investigations on the mechanical performance and durability of recycled aggregate concrete (RAC). Due to the loose and porous material properties of RA, the mechanical properties and durability of RAC, such as strength, carbonation resistance, permeability resistance and chloride ion penetration resistance, are greatly reduced compared with natural aggregate concrete. In contrast, concrete containing slag instead of NA and cement generally improved the strength of concrete and reduced the internal porosity of materials. Herein, we discuss the effects of RA and slag on the workability, compressive strength, splitting tensile strength, ultrasonic pulse velocity (UPV) value, and elastic modulus of concrete. The relationships between the compressive strength and the splitting tensile strength, UPV value, and elastic modulus are discussed, and the optimal substitution method is proposed. In addition, various equations for calculating the compressive strength of concrete based on performance factors related to the compressive strength are summarized.

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“…This was because the RFA with a 100% substitution rate was finer and contained more pores and old cement mortar [ 58 ]. Similar findings were found in another study on the effect of RFAs on the acid resistance of alkali-activated slag concrete (AASC), a new environmentally friendly cementitious material, where AASC with 0, 50, and 100% RFA replacement rates were exposed to a 3% sulfuric acid solution for 180 days, and it was found that the quality of AASC decreased as the replacement rate increased, but even after 180 days of exposure, the maximum mass loss of AASC was less than 20% (as shown in the figure), which was mainly due to the presence of GGBS in AASC [ 103 ] ( Figure 7 ). The acid resistance of SSC prepared with coarse and fine recycled aggregates in 5% sulfate was better than the control.…”

Section: Acid Resistancementioning

confidence: 99%

The Durability of Recycled Fine Aggregate Concrete: A Review

Лю

Lü

et al. 2022

Materials

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With the rapid development of urbanization, many new buildings are erected, and old ones are demolished and/or recycled. Thus, the reuse of building materials and improvements in reuse efficiency have become hot research topics. In recent years, scholars around the world have worked on improving recycle aggregates in concrete and broadening the scope of applications of recycled concrete. This paper reviews the findings of research on the effects of recycled fine aggregates (RFAs) on the permeability, drying shrinkage, carbonation, chloride ion penetration, acid resistance, and freeze–thaw resistance of concrete. The results show that the content of old mortar and the quality of recycled concrete are closely related to the durability of prepared RFA concrete. For example, the drying shrinkage value with a 100% RFA replacement rate is twice that of normal concrete, and the depth of carbonation increases by approximately 110%. Moreover, the durability of RFA concrete decreases as the RFA replacement rate and the water–cement ratio improve. Fortunately, the use of zeolite materials such as fly ash, silica fume, and meta kaolin as surface coatings for RFAs or as external admixtures for RFA concrete had a positive effect on durability. Furthermore, the proper mixing methods and/or recycled aggregates with optimized moisture content can further improve the durability of RFA concrete.

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Effect of recycled fine aggregates on alkali-activated slag concrete properties

Cited by 40 publications

References 36 publications

Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand

Performance of Steel Fiber-Reinforced Alkali-Activated Slag-Fly Ash Blended Concrete Incorporating Recycled Concrete Aggregates and Dune Sand

Effect of Recycled Aggregate and Slag as Substitutes for Natural Aggregate and Cement on the Properties of Concrete: A Review

The Durability of Recycled Fine Aggregate Concrete: A Review

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