Concrete strength
Concrete strength
(OP)
Hello all,
What is the best way to increase the strength of concrete if you are using the same sand and aggregate?
Thanks
What is the best way to increase the strength of concrete if you are using the same sand and aggregate?
Thanks
RE: Concrete strength
RE: Concrete strength
RE: Concrete strength
jayrod12. I agree with your first point but not your second. Lowering w/c ratio does not increase shrinkage. Increasing the total free water content is what increases shrinkage.
RE: Concrete strength
RE: Concrete strength
RE: Concrete strength
RE: Concrete strength
RE: Concrete strength
I've found over the years that many engineers do not understand concrete technology. They don't understand the impact of aggregate size, cement content (other than its impact on strength), the influence of admixtures on properties and strength gain, water additions at the site, placement techniques and other issues. This is unfortunate but true. The same is true of many contractors....even the superintendents and foremen. A foreman who tells the transit mixer driver to add more water likely has no idea of the impact of that water addition other than it makes the concrete easier and faster to place....his only concerns.
The person who knows or should know the concrete that's delivered better than anyone else is the QC representative of the concrete supplier. He/She should be the only person to dictate water addition at the site, particularly if the concrete is delivered to the site within the specified ranges of slump and air content.
retired13's synopsis is correct and good. I would add that once the mix design is correct for the application and is approved, it should not be changed by anyone without going back through an approval process. This includes adulteration of the mix at the site by water or admixture supplements.
Concrete specimens taken for compressive strength testing at the time of delivery are meant to test one thing....the mix design. They do not represent the concrete in the structure whether conventionally placed or pumped. That is not their intent. The intent is only to determine if you got what the mix design indicated you would get. That's what the structural design is based on...f'c.
One thing I throw out in my concrete lectures.....good concrete is made from water, cement and aggregates. Bad concrete is made from the same.
Pay attention to the details of concrete mix designs, placement conditions and site control. Concrete seems like a simple product, but it's actually a complex polymer with a lot of nuances that can be screwed up easily in the wrong hands.
RE: Concrete strength
I don't know who can say it better!
Ron, I was hoping to read something from you addressing a recent thread on "bridge inspection" after a fire event. Any thought/suggestion on that regard? Link