The adsorption amount, ξ-potential of cement particles and fluidity of cement paste were tested to research the competitive adsorption between naphthalene superplasticizer （FDN） and STPP. The experimental results s...The adsorption amount, ξ-potential of cement particles and fluidity of cement paste were tested to research the competitive adsorption between naphthalene superplasticizer （FDN） and STPP. The experimental results showed that the presence of STPP could significantly improve the fluidity of cement paste and reduce the fluidity loss with FDN. There existed a competitive adsorption between STPP and FDN. STPP and calcium ions formed complexes; they preferentially adsorbed onto surface of cement particles and preempt adsorption points of FDN; and it reduced adsorption amount of FDN. In the absence of STPP, saturation adsorption amount of FDN was 5.93 mg/g; but when the dosage of STPP was 0.1%, it reduced to 4.3 mg/g （about 72.5%）. The adsorption amount of FDN was reduced by STPP, but ξ-potential of cement particles enhanced and fluidity of cement paste increased because of strong negative charge effect of the complexes. Adsorption of the complexes would delay Ca^2＋ into liquid and inhibit formation of active adsorption points. Then, content of FDN in liquid increased with the addition of STPP and ξ-potential of cement particles became stable. In this way, fluidity loss of cement paste reduced.展开更多
基金Funded by the National Basic Research Program of China(973 Program)(2009CB23201)the National Natural Science Foundation of China(51378408)the Fundamental Research Funds for the Central Universities of China(WUT:2013-IV-036)
文摘The adsorption amount, ξ-potential of cement particles and fluidity of cement paste were tested to research the competitive adsorption between naphthalene superplasticizer （FDN） and STPP. The experimental results showed that the presence of STPP could significantly improve the fluidity of cement paste and reduce the fluidity loss with FDN. There existed a competitive adsorption between STPP and FDN. STPP and calcium ions formed complexes; they preferentially adsorbed onto surface of cement particles and preempt adsorption points of FDN; and it reduced adsorption amount of FDN. In the absence of STPP, saturation adsorption amount of FDN was 5.93 mg/g; but when the dosage of STPP was 0.1%, it reduced to 4.3 mg/g （about 72.5%）. The adsorption amount of FDN was reduced by STPP, but ξ-potential of cement particles enhanced and fluidity of cement paste increased because of strong negative charge effect of the complexes. Adsorption of the complexes would delay Ca^2＋ into liquid and inhibit formation of active adsorption points. Then, content of FDN in liquid increased with the addition of STPP and ξ-potential of cement particles became stable. In this way, fluidity loss of cement paste reduced.
