The Use of Lightweight Fines for the Internal Curing of Concrete
By George C. Hoff, P.E., DEng.
President, Hoff Consulting LLC
The benefits of using lightweight aggregates in concrete to
help reduce cracking in slabs and bridge decks has been
intuitively known for decades by the lightweight aggregate
industry but the reasons as to why this occurred were not
extensively examined and the benefits were not widely
promoted. It was believed, and correctly so, that the lower
modulus of the LWA and the improved transition zone around
the LWA particles due to their generally vesicular surface,
helped reduce stress concentrations between the paste and
the aggregate and those reductions subsequently reduced the
amount of early-age cracking in the concrete. In the 1980's,
the production of high-strength concrete (HSC) became more
common and, to accomplish it, came the use of higher cement
contents, supplementary cementing materials such as silica
fume, fly ash and blast furnace slag cement, and lower
water-binder ratios as a result of the extensive use of
superplastizers.
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