behnaz yahyaei | Kharazmi University Of Tehran (original) (raw)
Papers by behnaz yahyaei
Environmental Engineering and Management Journal, Dec 31, 2022
We assess the workability, mechanical properties, and durability of self-compacting concrete (SCC... more We assess the workability, mechanical properties, and durability of self-compacting concrete (SCC) incorporating silica fume (SF) and fly ash (FA) using tap water and seawater for making and curing. Leveraging a three-way ANOVA and Eigen analysis, we analyzed the results. Slump flow measurements, exhibit consistent behavior regardless of water type. The use of seawater instead of tap water leads to increased J-ring values, indicating potential enhancement in viscosity. Elevated SF content within SCC formulations further amplifies J-ring values, irrespective of water type. Air content experiences a minor rise with seawater, well within permissible limits. Optimal compressive strength, attained at 28 and 90 days, emerges from SCC samples containing 8% SF and 27% FA, produced with tap water and cured using seawater. Reversing the water types for production and curing yields comparable strength results. Conversely, SCC specimens produced and cured with seawater exhibit comparatively diminished strengths. Seawater employment for production and curing introduces marginal augmentations in water absorption (below 4%) and water penetration depth (7-33mm). Rapid Chloride Permeability Test values, ranging from 1000 to 2000 coulombs, indicate low chloride permeability across samples. Chloride concentration remains lower when seawater is utilized for production and tap water for curing, compared to the inverse scenario. The most notable chloride concentration (2.7-5% of concrete weight) arises when seawater is employed for both stages. The Rapid Chloride Migration Test manifests migration values of 4 to 7.8 (10-12 m²/s) for seawater production and tap water curing. Three-way ANOVA and Eigen-analysis provide robust statistical validation to the experimental outcomes.
Structural Concrete, Feb 4, 2021
Developing self‐compacting concrete (SCC) with higher workability and durability properties by re... more Developing self‐compacting concrete (SCC) with higher workability and durability properties by replacing mixing water with nano‐bubble without a decrease in mechanical strength is the purpose of this study. For this aim, different SCC mixtures were designed by using tap water and micro‐nano bubble and replacing silica fume, fly ash, slag, zeolite, and the mixture of fly ash and silica fume with cement. The workability, mechanical, and durability properties of the SCC mixture were tested according to ASTM and BS standards. In addition to air content test, for evaluation of the workability of SCCs, Slump flow in 10 and 60 min (for filling ability), V‐funnel, L Box, and J‐ring (for passing ability) were tested. For mechanical properties (compressive and tensile strength) and for durability of concretes (water penetration test and electrical resistivity) were tested. The workability test results indicate that using a micro‐nano bubble instead of tap water in different SCC mixture designs did not make a significant difference. But in hardened concretes, using the micro‐nano bubble increase the compressive and tensile strength of different concrete mixture designs except for SCC including fly ash and silica fume. Depth of water penetration and 30 min water adsorption for different concrete mix designs decreased compared to using tap water except for the sample contain zeolite, which increased slightly. Also, the permeability of concrete was tested by electrical resistivity. The results indicate that using the micro‐nano bubble decrease electrical resistivity and they were in the very low range (37–254 Ω‐m). The scanning electron microscope image confirmed in increasing mechanical and durability properties for a sample where used the micro‐nano bubble without pozzolans.
Civil engineering design, Mar 1, 2020
We studied the effects of superplasticizer (SP) (PCE1 and PCE2), air-entraining admixtures (AEA),... more We studied the effects of superplasticizer (SP) (PCE1 and PCE2), air-entraining admixtures (AEA), and supplementary cementitious material (silica fume and fly ash) on the mechanical and durability properties of concrete samples. Eight concrete mix designs were prepared. The first six concrete mix design contained similar aggregates, PCE2 SP, AEA, 350 kg/m 3 cement, and water to cement ratio equal to 0.38, and one of the mentioned mix design was selected as control samples with water to cement ratio equal to 0.57, without PCE2 SP and AEA. We used a different quantity of PCE2 SP and AEA and replaced the fly ash or silica fume as part of cement in two of the mentioned mix designs. The last two concrete mix designs studied the effect of PCE1 SP and AEA on freezing and thawing of concrete mix design. Adding PCE2 SP in concrete mix design increased compressive strength at age 11, 42, and 90 days sharply and reduced the depth of water penetration at the age of 28 and 90 days compared to the control sample. Using simultaneous PCE2 and AEA in concrete mix design did not improve compressive strength significantly and increased slightly depth of water penetration compared to only using PCE2. However, increasing the quantity of AEA to 5% improved both compressive strength and reduced depth of water penetration. In the second group of concrete mix design, adding both PCE1 and AEA increased the number of resistible freezing and thawing cycles of concrete. Side chain length and molecular weight of PCE1 and PCE2 SPs had no important effect on the compressive strength and performance properties of concrete. K E Y W O R D S durability, fly ash, air-entrained admixture, freezing and thawing, silica fume 1 | INTRODUCTION Concrete is one of the most commonly used building materials in the world. However, the long-term performance of the concrete and the influence of environmental parameters on its properties are not fully known. Concrete deteriorations and corrosion of steel reinforcement were generated, for example, by carbonation reaction, chloride ion penetration, freezing and thawing cycles, sulfate attacks, and alkaliaggregate reactions. Choosing and using inappropriate materials, the absence of quality control execution or poor performance of the quality control process and improper curing may shorten the service life and impose high costs. Therefore, some guidelines and standards were approved for concrete durability in constructions, especially in conditions that are vulnerable to environmental attacks such as chloride penetration, carbonation as well as freezing and thawing cycles. Economic impacts resulted from durability problems motivated scientists in the last three decades to do comprehensive researches on this issue, which provided an appropriate basis to increase the durability of concrete structures. 1 Concrete properties such as strength, durability, shrinkage, and permeability are directly influenced by the number, size and distribution of pores in cement paste, aggregate characteristics and interface
Structural Concrete, May 17, 2022
This research investigated the effect of using micro‐nano bubbles and superplasticizers on the rh... more This research investigated the effect of using micro‐nano bubbles and superplasticizers on the rheology of self‐compacting concrete (SCC). Eight mix designs were made with different values of 4–5.5 kg/m3 of superplasticizer. For comparison, half of the mix designs were made with micro‐nano bubbles, and the rest were made with tap water. Flowability, passing ability, and rheological tests were performed on all mixed designs. The results show that an increased rate of superplasticizer from 4 to 5 kg/m3 improved flowability and passing ability in all specimens. The yield stress and plastic viscosity of SCC reduction were higher in samples made with micro‐nano bubbles. The shear‐thickening behavior was observed in SCC samples produced with tap water and the superplasticizer, and the c/μ (positive) ratio increased. While in SCC with micro‐nano bubbles, the shear‐thinning behavior was observed, and the c/μ (negative) ratio increased with increasing the superplasticizer dose.
Structural Concrete, 2021
Developing self‐compacting concrete (SCC) with higher workability and durability properties by re... more Developing self‐compacting concrete (SCC) with higher workability and durability properties by replacing mixing water with nano‐bubble without a decrease in mechanical strength is the purpose of this study. For this aim, different SCC mixtures were designed by using tap water and micro‐nano bubble and replacing silica fume, fly ash, slag, zeolite, and the mixture of fly ash and silica fume with cement. The workability, mechanical, and durability properties of the SCC mixture were tested according to ASTM and BS standards. In addition to air content test, for evaluation of the workability of SCCs, Slump flow in 10 and 60 min (for filling ability), V‐funnel, L Box, and J‐ring (for passing ability) were tested. For mechanical properties (compressive and tensile strength) and for durability of concretes (water penetration test and electrical resistivity) were tested. The workability test results indicate that using a micro‐nano bubble instead of tap water in different SCC mixture designs did not make a significant difference. But in hardened concretes, using the micro‐nano bubble increase the compressive and tensile strength of different concrete mixture designs except for SCC including fly ash and silica fume. Depth of water penetration and 30 min water adsorption for different concrete mix designs decreased compared to using tap water except for the sample contain zeolite, which increased slightly. Also, the permeability of concrete was tested by electrical resistivity. The results indicate that using the micro‐nano bubble decrease electrical resistivity and they were in the very low range (37–254 Ω‐m). The scanning electron microscope image confirmed in increasing mechanical and durability properties for a sample where used the micro‐nano bubble without pozzolans.
Journal of Building Engineering
Environmental Engineering and Management Journal, Dec 31, 2022
We assess the workability, mechanical properties, and durability of self-compacting concrete (SCC... more We assess the workability, mechanical properties, and durability of self-compacting concrete (SCC) incorporating silica fume (SF) and fly ash (FA) using tap water and seawater for making and curing. Leveraging a three-way ANOVA and Eigen analysis, we analyzed the results. Slump flow measurements, exhibit consistent behavior regardless of water type. The use of seawater instead of tap water leads to increased J-ring values, indicating potential enhancement in viscosity. Elevated SF content within SCC formulations further amplifies J-ring values, irrespective of water type. Air content experiences a minor rise with seawater, well within permissible limits. Optimal compressive strength, attained at 28 and 90 days, emerges from SCC samples containing 8% SF and 27% FA, produced with tap water and cured using seawater. Reversing the water types for production and curing yields comparable strength results. Conversely, SCC specimens produced and cured with seawater exhibit comparatively diminished strengths. Seawater employment for production and curing introduces marginal augmentations in water absorption (below 4%) and water penetration depth (7-33mm). Rapid Chloride Permeability Test values, ranging from 1000 to 2000 coulombs, indicate low chloride permeability across samples. Chloride concentration remains lower when seawater is utilized for production and tap water for curing, compared to the inverse scenario. The most notable chloride concentration (2.7-5% of concrete weight) arises when seawater is employed for both stages. The Rapid Chloride Migration Test manifests migration values of 4 to 7.8 (10-12 m²/s) for seawater production and tap water curing. Three-way ANOVA and Eigen-analysis provide robust statistical validation to the experimental outcomes.
Structural Concrete, Feb 4, 2021
Developing self‐compacting concrete (SCC) with higher workability and durability properties by re... more Developing self‐compacting concrete (SCC) with higher workability and durability properties by replacing mixing water with nano‐bubble without a decrease in mechanical strength is the purpose of this study. For this aim, different SCC mixtures were designed by using tap water and micro‐nano bubble and replacing silica fume, fly ash, slag, zeolite, and the mixture of fly ash and silica fume with cement. The workability, mechanical, and durability properties of the SCC mixture were tested according to ASTM and BS standards. In addition to air content test, for evaluation of the workability of SCCs, Slump flow in 10 and 60 min (for filling ability), V‐funnel, L Box, and J‐ring (for passing ability) were tested. For mechanical properties (compressive and tensile strength) and for durability of concretes (water penetration test and electrical resistivity) were tested. The workability test results indicate that using a micro‐nano bubble instead of tap water in different SCC mixture designs did not make a significant difference. But in hardened concretes, using the micro‐nano bubble increase the compressive and tensile strength of different concrete mixture designs except for SCC including fly ash and silica fume. Depth of water penetration and 30 min water adsorption for different concrete mix designs decreased compared to using tap water except for the sample contain zeolite, which increased slightly. Also, the permeability of concrete was tested by electrical resistivity. The results indicate that using the micro‐nano bubble decrease electrical resistivity and they were in the very low range (37–254 Ω‐m). The scanning electron microscope image confirmed in increasing mechanical and durability properties for a sample where used the micro‐nano bubble without pozzolans.
Civil engineering design, Mar 1, 2020
We studied the effects of superplasticizer (SP) (PCE1 and PCE2), air-entraining admixtures (AEA),... more We studied the effects of superplasticizer (SP) (PCE1 and PCE2), air-entraining admixtures (AEA), and supplementary cementitious material (silica fume and fly ash) on the mechanical and durability properties of concrete samples. Eight concrete mix designs were prepared. The first six concrete mix design contained similar aggregates, PCE2 SP, AEA, 350 kg/m 3 cement, and water to cement ratio equal to 0.38, and one of the mentioned mix design was selected as control samples with water to cement ratio equal to 0.57, without PCE2 SP and AEA. We used a different quantity of PCE2 SP and AEA and replaced the fly ash or silica fume as part of cement in two of the mentioned mix designs. The last two concrete mix designs studied the effect of PCE1 SP and AEA on freezing and thawing of concrete mix design. Adding PCE2 SP in concrete mix design increased compressive strength at age 11, 42, and 90 days sharply and reduced the depth of water penetration at the age of 28 and 90 days compared to the control sample. Using simultaneous PCE2 and AEA in concrete mix design did not improve compressive strength significantly and increased slightly depth of water penetration compared to only using PCE2. However, increasing the quantity of AEA to 5% improved both compressive strength and reduced depth of water penetration. In the second group of concrete mix design, adding both PCE1 and AEA increased the number of resistible freezing and thawing cycles of concrete. Side chain length and molecular weight of PCE1 and PCE2 SPs had no important effect on the compressive strength and performance properties of concrete. K E Y W O R D S durability, fly ash, air-entrained admixture, freezing and thawing, silica fume 1 | INTRODUCTION Concrete is one of the most commonly used building materials in the world. However, the long-term performance of the concrete and the influence of environmental parameters on its properties are not fully known. Concrete deteriorations and corrosion of steel reinforcement were generated, for example, by carbonation reaction, chloride ion penetration, freezing and thawing cycles, sulfate attacks, and alkaliaggregate reactions. Choosing and using inappropriate materials, the absence of quality control execution or poor performance of the quality control process and improper curing may shorten the service life and impose high costs. Therefore, some guidelines and standards were approved for concrete durability in constructions, especially in conditions that are vulnerable to environmental attacks such as chloride penetration, carbonation as well as freezing and thawing cycles. Economic impacts resulted from durability problems motivated scientists in the last three decades to do comprehensive researches on this issue, which provided an appropriate basis to increase the durability of concrete structures. 1 Concrete properties such as strength, durability, shrinkage, and permeability are directly influenced by the number, size and distribution of pores in cement paste, aggregate characteristics and interface
Structural Concrete, May 17, 2022
This research investigated the effect of using micro‐nano bubbles and superplasticizers on the rh... more This research investigated the effect of using micro‐nano bubbles and superplasticizers on the rheology of self‐compacting concrete (SCC). Eight mix designs were made with different values of 4–5.5 kg/m3 of superplasticizer. For comparison, half of the mix designs were made with micro‐nano bubbles, and the rest were made with tap water. Flowability, passing ability, and rheological tests were performed on all mixed designs. The results show that an increased rate of superplasticizer from 4 to 5 kg/m3 improved flowability and passing ability in all specimens. The yield stress and plastic viscosity of SCC reduction were higher in samples made with micro‐nano bubbles. The shear‐thickening behavior was observed in SCC samples produced with tap water and the superplasticizer, and the c/μ (positive) ratio increased. While in SCC with micro‐nano bubbles, the shear‐thinning behavior was observed, and the c/μ (negative) ratio increased with increasing the superplasticizer dose.
Structural Concrete, 2021
Developing self‐compacting concrete (SCC) with higher workability and durability properties by re... more Developing self‐compacting concrete (SCC) with higher workability and durability properties by replacing mixing water with nano‐bubble without a decrease in mechanical strength is the purpose of this study. For this aim, different SCC mixtures were designed by using tap water and micro‐nano bubble and replacing silica fume, fly ash, slag, zeolite, and the mixture of fly ash and silica fume with cement. The workability, mechanical, and durability properties of the SCC mixture were tested according to ASTM and BS standards. In addition to air content test, for evaluation of the workability of SCCs, Slump flow in 10 and 60 min (for filling ability), V‐funnel, L Box, and J‐ring (for passing ability) were tested. For mechanical properties (compressive and tensile strength) and for durability of concretes (water penetration test and electrical resistivity) were tested. The workability test results indicate that using a micro‐nano bubble instead of tap water in different SCC mixture designs did not make a significant difference. But in hardened concretes, using the micro‐nano bubble increase the compressive and tensile strength of different concrete mixture designs except for SCC including fly ash and silica fume. Depth of water penetration and 30 min water adsorption for different concrete mix designs decreased compared to using tap water except for the sample contain zeolite, which increased slightly. Also, the permeability of concrete was tested by electrical resistivity. The results indicate that using the micro‐nano bubble decrease electrical resistivity and they were in the very low range (37–254 Ω‐m). The scanning electron microscope image confirmed in increasing mechanical and durability properties for a sample where used the micro‐nano bubble without pozzolans.
Journal of Building Engineering