More stories about Water-Cement Ratio

  • A Mix Design's Ingredients

    What can we tell our contractor-customers who insist on a low water-cement ratio but who then complain the concrete is hard to finish?

  • Eliminating Corrosion

    I recently read some papers on the corrosion of concrete in sewer manholes. Apparently, this is not a problem of gasses floating around in the sewer, but an issue of anaerobic bacteria (Thiobacillus) living on the surface of the concrete, creating sulfuric acid, which corrodes the concrete. The...

  • Normal Concrete Weight Loss

    I am working on providing material for crane counterweights. What is considered a normal weight loss (in pounds per cubic foot) for concrete from its plastic weight to a normal exposure weight after a month or two? My guess would be in the area of a pound or two per cubic foot.

  • More on Limestone Aggregate and Warehouse Floors: A Reader Responds

    As a specialist in industrial floor-hardening products, I am responding to a couple of comments in the "Troubleshooting" column from the October 2002 issue. The comments were in reference to specifying limestone as coarse aggregates in concrete floor slabs. In the last paragraph, the column...

  • Concrete Temperature and SCC

    One question recently posed on Aggregate Research Inc.Æs Industry Forum (www.aggregateresearch.com/forum) drew a number of interesting and important answers that may help you this season. The questioner wrote: ôIÆve noticed that a variation in ambient temperature can have a big effect on the...

  • What's the Allowable Fly Ash Limit?

    What is the highest percentage of fly ash that can be used in ready-mixed concrete? Is durability the most important issue in determining the limit?

  • Do Fibers Reduce Permeability?

    A customer has asked us to include fibers in the mix design for a water retention tank. The idea is that the fibers will reduce the permeability of the concrete. Is that true?

  • Flash Set vs. False Set

    We were supplying a slab on grade with ordinary 3000-psi concrete when a section of the slab flash set or possibly false set; we are not sure. What is the difference between the two? The contractor asked us if he should retemper the area with water or finish it. What should we have suggested to the...

  • The right way to truck-batch bagged pigment

    Recently we supplied an integrally colored pea-gravel mix for a job that used textured vertical formwork. The contractor insisted on adding the dissolvable color bags at the jobsite just prior to placement. We dispatched 8-cubic-yard loads in standard 10-cubic-yard rear-discharge mixers. The driver...

  • Problems with Trial-Batch Record Submittals