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Workability hydroxycarboxylic acids

Although the pictorial comparison shown in Fig. 1.1 and discussed above is true at low and average cement contents up to about 350 kg m it is more difficult to obtain higher strengths and workability by further increasing the cement content. It is in this area that the hydroxycarboxylic acid water-... [Pg.27]

The increase in workability obtained is, or course, a function of the dosage of admixture used and this is illustrated in Fig. 1.27 for lignosulfonates and the hydroxycarboxylic acid material. It will be appreciated that considerable retardation would be obtained at the higher dosage levels. [Pg.64]

Table 7.5 presents a comparison of the results obtained from concrete batches produced on the same plant with and without admixtures. The table summarizes data collected over a 6-month period for two concretes of differing slump values (50 mm and 75 mm). It can be seen that the hydroxycarboxylic-acid-based normal water-reducing admixture produced no effect on the standard deviation for the 50 mm slump mixes, whilst an increase is noted for the higher-workability mixes. [Pg.412]

Many concrete producers use a combination of superplasticizer and a conventional water-reducing, set-modifying or air-entraining admixture to achieve the desired performance. The superplasticizer provides the major portion of the required water reduction and the conventional admixture is added to achieve one or more of the following objectives (1) further water reduction (2) admixture economy (3) the desired air content (4) increased workability and (5) extension of set and workability. Coimnercial conventional admixture formulations used for this purpose are usually based on sodium lignosulfonates, hydroxycarboxylic acids or processed carbohydrates. Such combinations, besides reducing the dosage of the... [Pg.446]

When fatty-acid or wax emulsion type damp-proofers are used in conjunction with lignosulfonate or hydroxycarboxylic-based admixtures, heavy air entrainment results with attendant strength reduction. Both these effects decrease waterproofing characteristics. At higher workabilities, ligno sulfonates counteract the reduced bleeding effect obtained with waxes and increase bleeding rates [83]. [Pg.536]


See other pages where Workability hydroxycarboxylic acids is mentioned: [Pg.26]    [Pg.64]    [Pg.68]    [Pg.78]    [Pg.91]    [Pg.112]    [Pg.417]    [Pg.51]    [Pg.59]    [Pg.69]    [Pg.86]    [Pg.311]    [Pg.142]    [Pg.168]    [Pg.413]   


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