More stories about Ready-Mixed Concrete

  • What's in a Name?

  • Concrete Too Salty?

    Does the water for concrete have to be completely void of salt (from seawater)? What happens if it is not?

  • Rev Up Your Engines

  • Insight on C Mixes

    I have an answer for the definition of a C-4 mix (ôDesign Specs for a C-4 Wall,ö February 2002. IÆm working with a concrete contractor who is pouring C-4 for his footings in the morning, setting wall forms, and pouring them with C-4 that same day in winter conditions. What is your opinion of this...

  • 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?

  • Does Intermediate Rounding Decrease Accuracy?

    I have a further question regarding the rounding of compressive strength results (ôHow Precisely Should Labs Round off Compressive Strength Results?ö April, page 26).At our lab, we test 4x8-inch and 6x8-inch concrete cylinders for compressive strength, and we round to the nearest 10 psi according...

  • Algae in Mix Water Can Affect Air, Strength

    We recently supplied a house slab where the bleedwater had a greenish tint. We discovered that the water retention pond we used for water collection had green algae that had formed on the surface and was used for concrete production. The concrete met and gained strength normally, however. Is there...

  • 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?

  • Nitpicking Slump-Test Results

    A testing firm employee says concrete should be rejected if the slump exceeds the maximum allowable value by as little as 1/4 inch. Is there any published information to help us argue our case?

  • Who Pays for Comparative Testing?

    We're supplying concrete for a parking deck, to be placed by boom pump. The required air content is 4.5% to 7.5%, and, to account for air lost during pumping, specifications require the test lab to perform air-content tests on concrete sampled from the pump discharge hose. We prefer testing for air...