Admixtures types

Water-reducing admixture type Addition ievei Water-cement ratio... 

Admixture type Dosage Extension of initial setting time (h) at 20°C ... 

Reference Admixture type Compressive strength (. Flexural Tensile ... 

Although there are some anomalies in the literature, it is generally agreed that both types of volume deformation are a function of the same fundamental mechanism and that the influence of other factors such as admixtures will affect both shrinkage and creep in a similar manner. As outlined earlier, water-reducing admixtures can be used to obtain different effects on the plastic/hardened concrete and it is this factor, together with the admixture type, that is important in determining the effect on the volume deformations of concrete. 

Most admixtures of this type do not significantly alter the rheology of cement pastes at early ages. The quicker stiffening of accelerated pastes will, of course, result in higher viscosities at a later age. More complex formulations occasionally include water-reducing admixtures to reduce the water-cement ratio, and their effect will be a function of the water-reducing admixture type and content (see Section 1.3.1). 

Accelerating admixture type Stiffening time (h) for penetration resistance of 0.5 N mm- 3.5 N mm-2... 

Admixture types and addition levels which necessitate the use of increased water contents in the mix will increase drying shrinkage. 

ASTM recognizes three types of retarding admixtures type B, which simply retards the hydration of Portland cement type D, which not only provides set retardation but also water reduction and type G, which is a retarding supeplasticizer. The materials that are generally used in these admixtures include ... 

Table 7.33 Preferred point of addition in the mixing cycle for different admixtures types...

Dean M, Stephens JC, Winkler C, et al Polymorphic admixture typing in human ethnic populations. Am J Hum Genet 55 788-808,1994 de Chaldee M, Laurent C, Thibaut F, et al Linkage disequilibrium on the COMT gene in French schizophrenics and controls. Am J Med Genet 88(5)452-457,1999... 

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