Branched alkyl polyethers as novel defoamers for concrete

Chen, Jian; Shan, Guangcheng; Wu, Jingzhi; Qiao, Min; Gao, Nanxiao; Ran, Qianping

doi:10.1016/j.cemconres.2022.106821

Cited by 14 publications

(8 citation statements)

References 30 publications

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“…Figure 5 shows that the foam heights of all the samples increased gradually with the foaming time, and then decreased with the incubation time. The maximum foam heights decreased with the decrease in the amount of EO units, indicating that the defoamer containing less EO (higher hydrophobicity) had a higher defoaming ability in aqueous solutions [ 18 , 19 ]. It was also observed that compared with the defoamers linked with EO only, the defoamers linked with both EO and PO caused the foam heights to decay more quickly during the incubation time, and the defoamer linked with PO before EO (OPE2) caused the foam height to decay the most quickly.…”

Section: Resultsmentioning

confidence: 99%

“…Defoamer is a chemical admixture which has been widely used to inhibit and eliminate the harmful, large bubbles in fresh concrete [ 17 ]. By reducing the harmful bubbles and optimizing the pore structure of concretes, defoamers can improve the mechanical properties and service life of hardened concretes [ 18 , 19 ].…”

Section: Introductionmentioning

confidence: 99%

“…From the chemical composition, commonly used defoamers can be divided into four types, including fatty acids, mineral oils, polyethers and silicones [ 21 , 22 , 23 , 24 , 25 , 26 , 27 ]. Among them, polyether-type defoamers show the best water solubility and highest compatibility with polycarboxylate (PCE) superplasticizer, and have been most widely used as concrete admixtures [ 18 ]. However, synthetic polyethers have only rarely been reported as the defoamers for concrete.…”

Section: Introductionmentioning

confidence: 99%

“…In our previous study, we reported the polyether-type defoamers (amphiphilic surfactants) consisting of different hydrophobic alkyl chains (linear or branched, C14–25) and the same hydrophilic polyether chain (8 ethylene oxide units), which exhibited excellent defoaming performance [ 18 , 19 ]. The effect of hydrophobic alkyl chains on defoaming properties has been investigated, but the influence of a hydrophilic polyether chain (length and sequence) is still unknown.…”

Section: Introductionmentioning

confidence: 99%

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Preparation and Properties of Different Polyether-Type Defoamers for Concrete

Qiao

Gao

et al. 2022

Materials

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In this study, a series of polyether-type defoamers for concrete which consist of the same alkyl chain (hydrophobic part) but different polyether chains (hydrophilic part) was prepared, and the structure–property relationship of the defoamers was investigated for the first time. Using oleyl alcohol (OA) as the starting agent (alkyl chain), the polyether defoamers with different polyether chains were prepared by changing the amount and sequence of ethylene oxide (EO) and propylene oxide (PO) units. The properties of different defoamers were tested in aqueous solutions, and fresh and hardened mortars; the structure–property relationship of the defoamers was thus studied. The results indicated that the defoaming capacity of the polyether defoamers decreased with an increased EO amount, and the defoamers linked with both EO and PO units (PO before EO) had a stronger defoaming capacity than those linked with EO only. This study is beneficial for the development and applications of novel synthetic polyether-type defoamers for concrete.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Preparation and Properties of Different Polyether-Type Defoamers for Concrete

Qiao

Gao

et al. 2022

Materials

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“…Using the control method of “first elimination and then introduction”, the ratio of bubble area to the analysis area and the number of bubbles above 1 mm were greatly reduced, which played a significant role in improving the concrete surface appearance. The composite mixing of defoamer and PCE superplasticizer greatly affected the bubble spacing coefficient and bubble pore-size distribution of the concrete [ 68 , 69 ], among which the foaming and foam stabilization properties of the air-entraining agents played the most important role in affecting the concrete appearance [ 70 ]. A comprehensive comparison of Figure 21 reveals that the combined use of chemical admixtures can achieve a dynamic balance between improving and reducing workability, optimize the bubble structure, and enhance the bubble stability, thereby improving the concrete appearance quality [ 32 ].…”

Section: Influence Of the Structure Of Concrete Bubbles On The Appear...mentioning

confidence: 99%

Bubble Evolution under the Action of Polycarboxylate and Air-Entraining Agent and Its Effects on Concrete Properties—A Review

et al. 2022

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In order to improve the performance of concrete, it is of great significance to have a better understanding the mechanism and main influencing factors of concrete bubble evolution under the action of polycarboxylate and air-entraining agents. In the present review, with respect to the generation, growth, stability, and rupture of concrete bubbles under the action of polycarboxylate and air-entraining agents, this paper discusses the influence of bubble characteristics on concrete performance and studies bubble regulation by air-entraining agents and polycarboxylate (PCE) superplasticizer. The results show that the acid-to-ether ratio, sulfonic acid group, ester group, and the type of air entraining agent of the polycarboxylate acid structure have a significant impact on the bubbles. The bubble size, specific area, spacing factor, and bubble content have a significant impact on the rheological properties and related mechanical properties of fresh concrete and also affect the appearance quality of concrete. The problems with the experimental methods and theoretical models of concrete bubble research were analyzed, and future research ideas were put forward.

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