Superplasticizers for Concrete

Dehscofix. [Albright Wilson Am. Albright Wilson UK] Naphthalene sulfonic acid salts or condensates dispersant for agric. formulations superplasticizer for concrete. 

Spiratos, N., Page, M., Mailvaganam, N.P, Malhotra, V.M., Jolicoeur C. Superplasticizers for Concrete. Marquis, Quebec (2006)... 

The use of plasticizers and superplasticizers for concretes initiated on a large scale in the 1980s was a considerable step forward in the development of concrete as a structural material. These admixtures enabled production of high strength and high performance concrete due to reduced volume of water necessary for required workability of the fresh mix. Together with other innovations, this was the basis for a new and fascinating period of development of concretes, which extends to the present time (Brandt and Kucharska 1999). 

Reknes, K., Jha, P., Sharma, S. and Chuah, P. (2008) A lignosulfonate superplasticizer for concrete, in ACI-India Conference in Sustainable Development of Concrete, Ratnagiri, India, 2008. 

Research into the susceptibility of superplasticized concrete to sulfate attack has concluded that there is no significant difference between plain concrete and the admixture-containing concrete [71, 72]. Figure 2.22 presents some data for concretes containing an SNF superplasticizer exposed to a 3% magnesium sulfate solution. 

Compatibility with other admixtures due to the inherent surfactant properties exhibited by most of the materials in classes A, B and C, their use with other admixtures such as water reducers should be evaluated in terms of the side effects on the plastic and hardened concrete, viz. severe set retardation and excessive air entrainment. The molecules of materials with fewer surfactant properties compete with the superplasticizer for adsorption sites on the cement particle. This will result in a higher dosage of the superplasticizer. 

Y.F. Houst P. Bowen et al. Design and function of novel superplasticizers for more durable high performance concrete. Cement and Concrete Research, v. 38-10, October (2008), p. 1197-1209. 

A new water-soluble sulfonated phenolic resin as a potential superplasticizer was prepared from formaldehyde, phenol, and sodium bisulfite (NaHSOs) through a four-step reaction procedure. It was found that this resin could reduce the water content and improve the workability and compressive strength of concrete. The best results were obtained for concrete containing 2 wt% resin, which are comparable with commercial superplasticizers (128,174-176). 

In concrete, slump can be increased substantially by the addition of superplasticizers. For example, a slump of 260 mm from an initial slump value of 50 mm is obtained by an addition of 0.6% SMF the same value is realized with an addition of 0.4% SNF. The time when the superplasticizer is added to concrete affects the slump value. By adding the admixture with the mixing water, the slump is increased, but even higher values result if the admixture is added a few minutes after the concrete is mixed with water. 

Uses Surfactant water-reducer, superplasticizer for high strength concretes Properties Powd. 40% solids Canionic NB [Centro China]... 

With a direct addition of superplasticizer to obtain highly workable concrete, initial and final setting times are invariably increased in the order SMF < SNF < polyacrylates. At normal dosages this increase rarely exceeds two hours for materials that are not intentionally formulated to retard. 

Table 2.6 Data on creep measurements for control and water-reduced superplasticized concrete...

Most of the studies in this area have indicated that superplasticized concrete has shrinkage and creep characteristics similar to plain concrete. Figure 2.21 illustrates the shrinkage results of plain and superplasticized concrete [66], while Table 2.6 shows similar results for creep [67]. 

The types of water-soluble polymers used for the thickening cement slurries, mortar and concrete are shown in Table 6.6. Although many polymers shown in Table 6.6 can be used to increase the viscosity of the water in the mix, they are not all pseudoplastic polymers compatible with cement systems. Only a few can be consistently combined with water-reducing admixtures (WRAs) and superplasticizers to produce concretes with cohesive yet highly flowable mixtures [40, 41, 43]. 

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