Development of a short test for the identification of aggregates causing poor concrete performance when frozen

The purpose of this thesis is to develop a fast, simple and economical method to separate bad from good aggregates which will undergo the freezing and thawing of natural weather conditions after incorporation in concrete.

Freeze-thaw teats of air-entrained concrete specimens, teats on curing period of air-entrained concrete specimens exposed to freeze-thaw cycles, and mercury-intrusion porosimeter tests of individual aggregate particles were conducted.

Several parameters have been obtained from these tests. They are: durability factors at 100 cycles, slope of curves of time vs. length change, slope of curves of temperature vs. length change, residual length change, slope of entire first freeze curve, total porosity, porosity in certain pore size range, slope of pore size distribution curve in certain pore size range, and pore modulus.

A significant relationship exists between the durability factors and the slope of curves of time vs. length change, the durability factors and the slope of curves of temperature vs. length change, and the durability factors and the pore modulus. A good relationship also exists between the durability factors and the other parameters.

The original goal of a quick, simple, and inexpensive method to distinguish bad from good aggregates is obtainable. Separation of bad good aggregates can be by either running freeze-thaw teats to obtain values of slope of curves of time vs. length change and values of slope of curves of temperature vs. length change or running poresimeter tests to obtain pore modulus.