Effect of fly ash and metakaolin on pervious concrete properties

Saboo, Nikhil; Shivhare, Shekhar; Kori, Krishna Kumar; Chandrappa, Anush K.

doi:10.1016/j.conbuildmat.2019.06.185

Cited by 137 publications

(62 citation statements)

References 19 publications

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“…Figure 8 shows the microstructure of specimen (the reference concrete, HPC-2 and HPC-4) subjected to RT and 400 • C, respectively. Higher internal structure and more hydration products of specimens could be found on specimens (HPC-2 and HPC-4) than on the reference concrete, this due to the pozzolanic reaction of the SCMs, as well as combined usage of SCMs that optimized particle grading [14]. Therefore, HPC modified with SCMs showed higher residual strength than that of the control mix, as illustrated in [23].…”

Section: Microstructure Observationsmentioning

confidence: 94%

“…Supplementary cementitious materials (SCMs) contribute to improve the performance of concrete at high temperatures owing to their pozzolanic effects and super micro-filling capacity [14]. Furthermore, the residual unhydrated cementitious materials particles, such as: cement, activated slag [7], FA [14] and MK [7,15] can further react with water, which mainly comes from the vaporization of moisture [2] and dehydration of calcium hydroxide (CH), leading to the formation of dense hydration products [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Tang

Zhang

et al. 2020

Materials

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Concrete has low porosity and compact microstructure, and thus can be vulnerable to high temperature, and the increasing application of various types of supplementary cementitious materials (SCMs) in concrete makes its high-temperature resistant behavior more complex. In this study, we investigate the effects of four formulations with typical SCMs combinations of fly ash (FA), ultra-fine fly ash (UFFA) and metakaolin (MK), and study the effects of SCMs combinations on the thermal performance, microstructure, and the crystalline and amorphous phases evolution of concrete subjected to high temperatures. The experimental results showed that at 400 °C, with the addition of 20% FA (wt %), the thermal conductivity of the sample slightly increased to 1.5 W/(m·K). Replacing FA with UFFA can further increase the thermal conductivity to 1.7 W/(m·K). Thermal conductivity of concrete slightly increased at 400 °C and significantly reduced at 800 °C. Further, combined usage of SCMs delayed and reduced micro-cracks of concrete subjected to high temperatures. This study demonstrates the potential of combining the usage of SCMs to promote the high-temperature performance of concrete and explains the micro-mechanism of concrete containing SCMs at high temperatures.

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Section: Microstructure Observationsmentioning

confidence: 94%

Section: Introductionmentioning

confidence: 99%

Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Tang

Zhang

et al. 2020

Materials

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“…Work by Ma [19] studied the heavy metal leaching of iron tailings, which shows that the concentration of heavy metal leaching of iron tailings is within the range of Chinese standards of GB/T 5085.3 [20]. Table 1 summarizes the variables and properties of pervious concrete using different aggregates [21][22][23][24][25][26][27][28]. We can draw two conclusions from Table 1: (1) The substitution of solid waste for the natural aggregate of pervious concrete has attracted much attention.…”

Section: Introductionmentioning

confidence: 94%

“…The optimum porosity ranged from 7.5% to 16.5%, which provides a theoretical basis for the mix design and performance for the preparation of pervious concrete. Figure 11 shows the comparisons of the permeability coefficient (A) and compressive strength (B) of pervious concrete with different types of aggregates [21][22][23][24][25][26][27][28]. Although different experimental conditions such as porosity type (fresh state, total, or open), test method and samples size may restrict the comparison of the properties of pervious with different types of aggregates, Some useful information can still be found by summarizing and analyzing these pervious concretes.…”

Section: Compressive Strength Of Pervious Concretementioning

confidence: 99%

Evaluation of the Hydraulic, Physical, and Mechanical Properties of Pervious Concrete Using Iron Tailings as Coarse Aggregates

2020

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Aggregates are a significant component of pervious concrete. Pervious concrete using iron tailings as coarse aggregates was prepared to study the feasibility of this approach. A mix design procedure was also used to design pervious concrete based on different target porosities. The effective porosity, measured porosity, dry density, compressive strength, and permeability coefficient of pervious concrete were studied. The results show that the mix design procedure based on a target porosity is relatively reasonable for designing iron tailing-based pervious concrete. The 28 d compressive strength of the pervious concrete decreased from 42 to 11 MPa as the effective porosity increased from 5.2% to 27.2%. The effective porosity of the equilibrium point of the compressive strength and permeability coefficient of pervious concrete was approximately 16%, where the compressive strength was 21.5 MPa, and the water permeability was 3.2 mm/s. The permeability coefficient of pervious concrete can be predicted as an exponential function of the effective porosity, and the compressive strength of pervious concrete can be predicted as a logarithmic function of the effective porosity.

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“…Because of this physical condition, the use of fly ash in concrete contributes many advantages in improving the physical and mechanical properties of concrete. The physical and mechanical properties of concrete that can be improved include a lower permeability [2], lower water absorption [3,4], increased tensile strength [5], lower abrasion resistance [6], increased durability [7], lower hydration heat during cement hydration, a decrease in cracks because of smaller shrinkage, and a higher compressive strength of the concrete at 28 days [8]. The high SiO 2 content in fly ash greatly contributes to the increase in the compressive strength of concrete.…”

Section: Introductionmentioning

confidence: 99%

Effect of Calcium Stearate in the Mechanical and Physical Properties of Concrete with PCC and Fly Ash as Binders

et al. 2020

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This work aims to study the effect of Ca(C 18 H 35 O 2 ) 2 (calcium stearate) on the properties of concrete by using Portland composite cement (PCC) and fly ash as binders. The calcium stearate content used in the concrete here consists of 0, 1, 5, and 10 kg per m 3 of concrete volume, or alternatively, 0 to 2.85% by the weight of cement. We have performed several tests for each of the contents, namely, compressive strength, water absorption, chloride ion infiltration, and accelerated corrosion tests. According to the testing, we have found that with the addition of calcium stearate at 1 kg/m 3 in self-compacting concrete (SCC) with 10% fly ash, the mechanical and physical properties of SCC can be improved significantly when compared to the SCC without fly ash and calcium stearate, resulting in a stable compressive strength, lower water absorption, lower chloride ion infiltration, and lower degree of corrosion attack.Materials 2020, 13, 1394 2 of 16 calcium silicate hydrate mineral referred to as C-S-H (tobermorite) [9]. Calcium hydroxide itself is one of the compounds formed when tricalcium silicate (C3S), dicalcium silicate (C2S), or tricalcium aluminate (C3A) reacts with water (H 2 O). The use of fly ash in concrete as a substitute for cement further increases the amount of C-S-H/calcium silicate hydrate (tobermorite) formed during the cement hydration process. It can reduce cement the consumption by 3.2-5 kg·m −3 ·MPa −1 [10]. In the process of cement production, millions of tons of CO 2 gas (a pollutant) is released because of combustion to make clinker. Reducing cement consumption in concrete consequently decreases the CO 2 emissions. Besides that, the appearance of fly ash in concrete also raises the alkalinity of concrete [11]. The higher the alkalinity of concrete, the greater the passive layer protected steel bar in concrete is from corrosion attack.Not only additives such as fly ash, slag, and silica fumes, but superplasticizers such as water reducers [12] in concrete also can reduce the capillaries and pores [13] in concrete. Although the water/cement ratio used in concrete is very small, the workability of fresh concrete remains good, and this is easily maintained by adding a superplasticizer to the concrete [14]. Because of the low water/cement ratio used, autogenous shrinkage is reduced. Other effects include increasing the elastic modulus [15] and raising the anti-carbonation of the concrete [16].A large contact angle makes it more difficult for water to seep into concrete [17]. As a result, the water absorption of concrete also drops significantly. Furthermore, in general, chloride ions penetrate into concrete along with water because of the greater contact angle. Automatically, concrete-containing large silica particles are more resistant to corrosion attack. On the contrary, in concrete made with the addition of a water-entraining agent [18], chloride ions enter into concrete more easily, especially in young concrete [19,20]. Corrosion attack on the concrete reinforcement surface causes cracks ...

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Effect of fly ash and metakaolin on pervious concrete properties

Cited by 137 publications

References 19 publications

Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Effects of Combined Usage of Supplementary Cementitious Materials on the Thermal Properties and Microstructure of High-Performance Concrete at High Temperatures

Evaluation of the Hydraulic, Physical, and Mechanical Properties of Pervious Concrete Using Iron Tailings as Coarse Aggregates

Effect of Calcium Stearate in the Mechanical and Physical Properties of Concrete with PCC and Fly Ash as Binders

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