Hot to explain the fact that for the same concrete mixture:
*slum at noon 75mm temperature 39 degrees Celsius
*slum of 8Pm 195mm temperature 28 degrees Celsius
*all both mixtures had Additives (classification) and cement 400Kg and water 180l.
Concrete designed using Dreux Method
This concrete is for pumping and used for beam.
My question is: what is better between adding more water and adding more additives ?
Its always better to add more admixtures as increase in water will reduce the strength of the concrete and more proneness to segregation and bleeding. However, can you specify the admixture you used, is it superplasticizer.
For your mixtures, are you implying your mixtures didn't hardened for 8 hours based on the results you specified?
yeah the main problem is concrete with slum 75 can't be pump ... and for the plasticizer we using 1kg /cubic meter Sika... We focusing on casting concrete on evening and at night.
Using a low water to cementitious ratio and 1% plasticizer by mass of the cementitious component should give you the desired slump for pumping
Dear Papa NIANE Faye,
Workability of concrete mainly depends on water cement ratio, dosage of admixture, cement content and quality of aggregate. In your case details of mix proportion and properties of aggregates are not mentioned. It will be better to increase dosage of admixture instead of increasing water content. Normally dosage of admixture is not exceed 1.5%. For pumpable concrete, slump should be in the range of 100mm to 150 mm. Use of additive will help in making cohesive mix. Size and shape of aggregate also affect workability.
It is to be noted that admixture should be added during mixing only after adding 50 to 70 % of water required for the given mix. This will give better result as compared to mix in which admixture is added at initial stage of mixing. I hope that this will solve your problem
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