High-range water reducing admixtures

Fig. 7.9 High-strength concrete through the use of silica fume and a high-range water-reducing admixture...

HRWRA = high range water-reducing admixture (superplasticizer). WRA = water-reducing admixture. AEA = Air-entraining Admixture. ... 

Hester, W.T. (1979) Field Applications of High Range Water Reducing Admixtures, ACI SP-62, 533-57. 

The high-range water reducing admixtures (HRWRA) which are also called superplasticisers are admixtures that reduce the mixing water requirement of a concrete with a given consistency by more than 12% [20]. 

High-range water reducing admixtures (HRWRA)... 

ASTM C 494 (Specification for Chemical Admixtures for Concrete) classifies several types of concrete admixtures. Of particulcir use for steel in concrete are the high range water reducers that are classified as type F or G admixtures. These chemicals significantly improve concrete workability at low w/c ratios, which is needed to produce low permeability concrete. 

Commercial admixtures employed were a polyalkyl aryl sulfonate-type high range water-reducing agent, four polyoxyethylene nonylphenol ether-type... 

The effect produced by the incorporation of a lignosulfonate-based water-reducing agent is shown in Table 7.6. The results were obtained from a series of mixes over an 8-month period by a ready-mix plant used in the production of concrete piles. Since the standard deviation of this particular plant was 5.0 MPa for mixes produced without the use of admixtures, it is evident that the use of the admixture resulted in reduced variability. These results indicate that in high workability mixes with cement contents in the median range, the admixture may cause an increase in the standard deviation. Thus in redesigning the mix to have a lower cement content in this class of concrete, adequate consideration should be given to this difference in standard deviation. Increased uniformity can be attained in this instance... 

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