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Effect of the Side-Chain Length in Polycarboxylic Superplasticizer on the Competition Adsorption in the Presence of Montmorillonite: A Density Functional Theory Study
被引:1
作者:
He, Zhihao
[1
,2
]
Huang, Teng
[3
,4
]
Gao, Meiben
[1
,2
]
Kong, Desong
[3
]
Li, Meng
[3
]
机构:
[1] Xihua Univ, Sch Emergency Management, Chengdu 610039, Peoples R China
[2] Chengdu Univ Technol, Key Lab Geohazard Prevent & Geoenvironm Protect, Chengdu 610059, Peoples R China
[3] Southwest Univ Sci & Technol, Sch Environm & Resource, Mianyang 621010, Peoples R China
[4] Southwest Univ Sci & Technol, Key Lab Waste Treatment & Resource Recycle, Minist Educ, Mianyang 621010, Peoples R China
来源:
关键词:
PCEs;
compatibility;
clay;
cement concrete;
molecular simulation;
MOLECULAR-STRUCTURE;
CLAY TOLERANCE;
001;
SURFACE;
CEMENT;
MECHANISM;
DISPERSION;
BEHAVIOR;
WATER;
D O I:
10.3390/molecules29040752
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
Polycarboxylic superplasticizers (PCEs) exhibit numerous advantages as concrete additives, effectively improving the stability and strength of concrete. However, competitive adsorption of PCEs occurs in the presence of clay, which may affect the cement dispersion and water-reducing performance. Extensive research has been conducted on the physical and mechanical properties of PCEs; however, the effect of the diverse structures of PCEs on the competitive adsorption on clay and cement hydration products has been rarely studied. This study employs Ca-montmorillonite (CaMMT) as a clay representative, by constructing adsorption models of PCEs on CaMMT and cement hydration products. A comparison of the adsorption energies considering different side-chain lengths of PCEs is included. Typically, the adsorption energy on CaMMT is lower than that on hydration products, leading PCEs to preferentially adsorb on the clay, thereby reducing its effective dosage in the cement particles. The challenge of PCE adsorption on CaMMT increases with the polymerization degree, and methylallyl polyoxyethylene ether (HPEG) exhibits lower adsorption energies on CaMMT. The density of states (DOS) analysis indicated the highest peak values of allyl polyethylene ether (APEG) as well as the peak area at n (polymerization degree) = 1. The total number of transferred electrons for APEG was 0.648, surpassing those of other PCEs. The interaction mechanism of PCEs with clay and hydration products is further elucidated through electronic gain/loss analysis, also providing a basis for the theoretical analysis on how to reduce the adsorption of PCEs on clay and the structural design of mud-resistant PCEs.
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