Retempering of Prolonged-Mixed Concrete with Admixtures in Hot Weather

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Title: Retempering of Prolonged-Mixed Concrete with Admixtures in Hot Weather

Author(s): Dan Ravina

Publication: Journal Proceedings

Volume: 72

Issue: 6

Appears on pages(s): 291-295

Keywords: admixtures;compressive strength;concrete construction;concretes;fresh concrete;hot weather construction;mixing;mixing time;ready-mixed concrete; retardants;retempering;slump tests;water;water-reducing admixtures; workablity.

Date: 6/1/1975

Abstract:
The effect of water-reducing, and water-reducing and retarding admixtures on prolonged-mixed concete at 30 C (86 F) was studies over a range of dosages. Loss of slump during mixing (for 1 or 2 hr), and the total mixing water required for regaining the intial slump of 10 cm (4 in) after retempering, were measured. Results show that while the loss of slump was higher (compared with the reference concrete) with the admixtures, the total mixing water after retempering was less. At the reccommended dosage of admixtures, the differences in both parameters were very samll and so were the differences in compressive strength. At higher dosages, however, a pronounced reduction in the total mixing water was observed, with a parallel significant increase in strength.