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Kyongku Yun – One of the best experts on this subject based on the ideXlab platform.

  • air void structure strength and permeability of wet mix shotcrete before and after shotcreting operation the influences of silica fume and air entraining Agent
    Cement & Concrete Composites, 2016
    Co-Authors: Pangil Choi, Jung Heum Yeon, Kyongku Yun
    Abstract:

    Abstract It is well known that the air-void structure of hardened concrete has substantial effects on the mechanical properties and durability of concrete. In this study, laboratory evaluations were conducted to quantify the effects of Air-Entraining Agent (AEA) and silica fume on the air-void characteristics of wet-mix shotcrete (WMS) before and after shotcreting process. For this purpose, a high-resolution image analyzer capturing elaborate graphical layouts of air-void structure using the linear transverse method was employed. Also, this study examined the effects of air-void characteristics, such as air content and spacing factor, on the strength and permeability of WMS. Based on the findings of this study, it can be concluded that: (1) shotcreting process considerably reduces overall air contents in WMS; (2) incorporating AEA with a 4.5% silica fume replacement ensures both satisfactory spacing factor and good retention of small entrained air bubbles even after shotcreting, which may improve the freeze-thaw and scaling resistance; (3) the compressive and flexural strengths of WMS were reduced as the air content increased and average spacing factor decreased; and (4) the air content affected the permeability of WMS, but no consistent correlation was found between spacing factor and permeability.

Yong Jiang Xie – One of the best experts on this subject based on the ideXlab platform.

  • The rheological properties of self-compacting concrete containing superplasticizer and Air-Entraining Agent
    Construction and Building Materials, 2018
    Co-Authors: Huang Fali, Yi Zhonglai, Wang Zhen, Yong Jiang Xie
    Abstract:

    Abstract This work investigates the effect of a polycarboxylate superplasticizer (SP) and a rosin resin type Air-Entraining Agent (AE) on the rheological properties of powder-viscosity modifying admixture (VMA) combination type self-compacting concrete (SCC). The modified Bingham model was applied to describe the shear thickening behavior of this specific SCC. The results showed that both the yield stress and plastic viscviscosity of SCC deceased significantly while the shear thickening behavior of mixtures was intensified with an increase of SP dosage. The addition of AE led to an increase of yield stress and a decrease of plastic viscviscosity, whereas a high air content weakened the shear thickening behavior of SCC. The shear thickening behavior was found to be completely disappeared and shear thinning behavior occurred when the air content reached 8.7%, which indicated that increasing the air content was an easy and effective way to reduce the shear thickening behavior of SCC.

  • Quality Evaluation of Air Entraining Agent Based on Air Void Parameters of Fresh Concrete
    Key Engineering Materials, 2014
    Co-Authors: Lu Yang, Yong Jiang Xie
    Abstract:

    In order to evaluate the quality of air entraining Agent quickly and effectively. Air void parameters of fresh concrete with different air entraining Agents were studied by Air Void Analyzer (AVA). The spacing factor and durability index of hardened concrete were tested and the relationship between the surface tension of air entraining Agent and frost resistance of concrete was compared. The results showed that, the quality of air entraining Agent can be evaluated quickly and effectively by diameter distribution of air bubbles in fresh concrete and spacing factor of fresh concrete. AEA2 introduced much more big air bubbles into concrete which is bad for the frost resistance of concrete. The quality of AEA2 was the worst, so the durability index of hardened concrete was 58.7%. Quality of air entraining Agent cannot be characterized by properties of air entraining Agent, but air entraining ability can be characterized by surface tension of air entraining Agent. Keywords: air entraining Agent (AEA), air void parameter, fresh concrete

Quanbing Yang – One of the best experts on this subject based on the ideXlab platform.

  • deicer scaling resistance of phosphate cement based binder for rapid repair of concrete
    Cement and Concrete Research, 2002
    Co-Authors: Quanbing Yang, Shuqing Zhang, Xueli Wu
    Abstract:

    Abstract In this paper, a magnesium phosphate cement-based binder (MPB) was prepared by mixing MgO with mono-ammonium phosphosphate, borax and fly ash. The deicer-scaling resistance of MPB mortar and concrete and the bond strength loss between MPB paste and mortar with ordinary PortPortland cement (OPC) concrete were investigated. Experimental results show that MPB materials themselves have high deicer–frost resistance, which is not lower than that of OPC concrete with the air content of 4.5–6.5%. The bond strength loss between MPB materials and OPC concrete with the Air-Entraining Agent is obviously lower than that between MPB and OPC concrete without the Air-Entraining Agent, and the higher the air content in OPC concrete is, the smaller the loss is. Furthermore, the air-bubble parameters were analyzed, which indicate that MPB mortar and concrete can also obtain a reasonable air-bubble structure by chemical reactions.

  • Communication Properties of concrete with a new type of saponin Air-Entraining Agent
    , 2000
    Co-Authors: Quanbing Yang, Peirong Zhu, Shiyuan Huang
    Abstract:

    AbstractIn the present paper, a new type of Air-Entraining Agent (trademark SJ-2) is introduced, its main chemical component being triterpenoidsaponin. Many properties of fresh and hardened concrete with SJ-2, such as workability, bleeding, air-bubble system, stability of air bubbles,strength loss, frost/salt-scaling resistance, etc., are measured. Some of them are compared with those of concrete with Vinsol resin and abieticsoap (AS). Results show that SJ-2 is an Air-Entraining Agent with high quality, and most of the properties of concrete with SJ-2 are not lowerthan those of concrete with Vinsol; at the same conditions, the flexural strength loss of concrete with SJ-2 is remarkably lower than itscompressive strength loss. D2000 Elsevier Science Ltd. All rights reserved. Keywords: Saponin; Air-Entraining Agent; Concrete; Frost/salt-scaling resistance; Strength A large number of chemical substances can be used asAir-Entraining Agents of concrete. Many of these are refinedby-products from various industrial processes, such as pulp,paper, and petroleum production. The most commonly usedchemicals are sodium salts of wood resin (e.g. sodium-abietate, which is similar to Neutralized Vinsol resin, or justVinsol resin, which has been widely used for a very longtime), salts of fatty acids, salts of sulphonated hydrocarbon,alkyl-benzyl sulphonates, etc. [1].One of the most commonly used Air-Entraining Agents inthe world is the so-called Vinsol resin, see above. However,two types of Air-Entraining Agent, abietic soap (AS) orsodium abietate and sodium lignosulphonate are widelyused in China. Both Air-Entraining Agents have many short-comings, such as bad air-bubble system, high air contentloss, high strength loss per air content for sodium lignosul-phonate; bad water-solubility, some precipitation formationwhen used with sulphonated naphthalene condensate orsulphonated melamine_formaldehyde condensate togetherand high strength loss for AS. These obvious shortcomings,especially high strength loss, badly influence the applicationof Air-Entraining Agent, because the compressive strength isan important parameter for designing concrete in manyChinese standards.A new type of Air-Entraining Agent was first invented in1988 and its quality has been improved significantly sincethen [2], its main component being a surface active sub-stance, saponin. The admixture is refined from the fruits ofsome natural plants, such as Chinese honey locust. It hasbeen widely used in many kinds of concrete since 1990,such as high frost-resistance concrete, pumping concrete,and so on. In total about 3 million m

  • Properties of concrete with a new type of saponin Air-Entraining Agent
    Cement and Concrete Research, 2000
    Co-Authors: Quanbing Yang, Peirong Zhu, Shiyuan Huang
    Abstract:

    In the present paper, a new type of Air-Entraining Agent (trademark SJ-2) is introduced, its main chemical component being triterpenoid saponin. Many properties of fresh and hardened concrete with SJ-2, such as workability, bleeding, air-bubble system, stability of air bubbles, strength loss, frost/salt-scaling resistance, etc., are measured. Some of them are compared with those of concrete with Vinsol resin and abietic soap (AS). Results show that SJ-2 is an Air-Entraining Agent with high quality, and most of the properties of concrete with SJ-2 are not lower than those of concrete with Vinsol; at the same conditions, the flexural strength loss of concrete with SJ-2 is remarkably lower than its compressive strength loss.

Anuwat Attachaiyawuth – One of the best experts on this subject based on the ideXlab platform.

  • Effects of fly ash, mixing procedure and type of Air-Entraining Agent on coalescence of entrained air bubbles in mortar of self-compacting concrete at fresh state
    Construction and Building Materials, 2018
    Co-Authors: Nipat Puthipad, Masahiro Ouchi, Anuwat Attachaiyawuth
    Abstract:

    Abstract In this paper, an empirical study aimed at preventing the coalescence of fine entrained air bubbles in the fresh mortar of self-compacting concrete (SCC) containing fly ash is reported. The time of addition of the Air-Entraining Agent (AEA) during mixing is also investigated. Various types of AEA are also studied. In implementing the experiment, mortar flowability is assumed to affect the coalescence of fine air bubbles. The air size distribution of the air-entrained SCC mortar in the fresh state is determined by an Air Void Analyser (AVA). Changes in the air size distribution over a 120 min period are analysed to evaluate bubble coalcoalescence. The results suggest that the use of fly ash in the SCC can result in a higher degree of coalescence of the fine air bubbles. The various types of AEA resulted in air bubbles with different degrees of coalescence. Further, adding the AEA to the mix after the superplasticiser (SP) inhibits the coalescence of air bubbles. Evidently, the degree of coalescence of air bubbles can be reduced by careful selection of the AEA and the mixing procedure.

  • Improving the stability of entrained air in self-compacting concrete by optimizing the mix viscosity and air entraining Agent dosage
    Construction and Building Materials, 2017
    Co-Authors: Sovannsathya Rath, Masahiro Ouchi, Nipat Puthipad, Anuwat Attachaiyawuth
    Abstract:

    Abstract The purpose of this study is to clarify the role of mixing procedure and air entraining Agent (AE) on the entrained volume of fine and coarse air bubbles with the aim of improving the stability of entrained air in self-compacting concrete (SCC). Experiments were conducted in which the air bubbles size distribution of fresh mortars was measured with an air-void analyzer (AVA). Critical size of air bubble was defined as the size below which the bubble volume remains stable as time pass. This critical size, defined in terms of chord length, was found to be 500 μm from the correlation between the volume of larger bubbles and the reduction in volume two hours after mixing. A lower mortar viscosity, obtained using a mixing procedure in which water additions were divided, reduced the total volume of both fine and coarse air bubbles. With a higher dosage of AE, a higher volume of fine air bubbles and a lower volume of coarse air bubbles were entrained. An upper limit volume of fine air was defined as the maximum volume of fine air bubbles entrained with a longer mixing time. This upper limit is proportional to the AE dosage multiplied by the funnel speed of the mortar as an index of viscosity.

Pangil Choi – One of the best experts on this subject based on the ideXlab platform.

  • air void structure strength and permeability of wet mix shotcrete before and after shotcreting operation the influences of silica fume and air entraining Agent
    Cement & Concrete Composites, 2016
    Co-Authors: Pangil Choi, Jung Heum Yeon, Kyongku Yun
    Abstract:

    Abstract It is well known that the air-void structure of hardened concrete has substantial effects on the mechanical properties and durability of concrete. In this study, laboratory evaluations were conducted to quantify the effects of Air-Entraining Agent (AEA) and silica fume on the air-void characteristics of wet-mix shotcrete (WMS) before and after shotcreting process. For this purpose, a high-resolution image analyzer capturing elaborate graphical layouts of air-void structure using the linear transverse method was employed. Also, this study examined the effects of air-void characteristics, such as air content and spacing factor, on the strength and permeability of WMS. Based on the findings of this study, it can be concluded that: (1) shotcreting process considerably reduces overall air contents in WMS; (2) incorporating AEA with a 4.5% silica fume replacement ensures both satisfactory spacing factor and good retention of small entrained air bubbles even after shotcreting, which may improve the freeze-thaw and scaling resistance; (3) the compressive and flexural strengths of WMS were reduced as the air content increased and average spacing factor decreased; and (4) the air content affected the permeability of WMS, but no consistent correlation was found between spacing factor and permeability.