Adding super plasticizer at site-ACI (concrete) Code Issues Germany

  • Adding super plasticizer at site-ACI (concrete) Code Issues Germany
  • Adding super plasticizer at site-ACI (concrete) Code Issues Germany
  • Adding super plasticizer at site-ACI (concrete) Code Issues Germany
  • When did superplasticizers come out in concrete?
  • In May 1978, the Canada Centre for Mineral and Energy Technology (CANMET), in association with the American Concrete Institute (ACI) sponsored a 3-day conference in Ottawa, ON, Canada, on the use of superplasticizers in concrete. Selected papers from the conference were published as ACI SP-62.
  • Does plasticizer increase air content?
  • The problem comes when contractors add the plasticizer on the job site. It is expected to increase air content by at least 1.5% in a normal mix design but we have experienced the air increasing by up to 5% on some specialty (bridge deck, low shrinkage) mix designs that have fly ash, silica fume, retarder in the mix design as well.
  • Does plasticizing concrete elevate air content?
  • Jesse Espy, Pre-Mix Inc., Pullman, WA With superplasticizers, it has always been my experience that plasticizing concrete will elevate the air content. When training new workers (drivers, batch people, QC), I emphasize that it is primarily the increase in slump (when plasticizing) that brings the elevated air content.
  • Does superplasticizer cause air spikes?
  • In Eastern Washington across eight-plus concrete plants and many aggregate sources we do see air spikes from the addition of superplasticizer. Going from a mix without superplasticizer to an identical mix containing superplasticizer we typically have to reduce the air entraining admixture content by 50% to maintain the same air content.
  • What is the default air entrainment dosage for polycarboxylate superplasticizer?
  • For example, when we sell a customer 6.0 oz/cwt of [polycarboxylate superplasticizer] as an extra product to a mix so they can increase slump without adding water and shrinkage, our dispatch software automatically drops the air entrainment dosage in the mix for that order from its default of 0.6 oz/cwt to 0.4 oz/cwt.
  • Why should a superplasticizer be used a P R Oach?
  • Because superplasticizers allow c o n c r ete to be placed faster due to its flowing consistency, allow the placement of higher lifts, and re- t a r d set, the conservative design a p p r oach would be to use full liquid head when determining wall form p re s s u r es.

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