Title: Chemical Test for Reactivity of Aggregates with Cement Alkalies; Chemical Processes in Cement-Aggregate Reaction

Author(s): Richard C. Mielenz and Kenneth T. Greene and Elton J. Benton

Publication: Journal Proceedings

Volume: 44

Issue: 11

Appears on pages(s): 193-222

Keywords: none

DOI: 10.14359/8788

Date: 11/1/1947

Abstract:
Potential deleterious reactivity of aggregates with high-alkali cements can be predicted from results of a newly developed chemical test. Determination of deleteriousness is based on the amount of silica dissolved by a IN sodium hydroxide solution from a representative sample of the aggregate crushed to the No. 50 to No. 100 size, and the concomitant reduction effected in the alkalinity (potency) of the solution. The samples can be prepared, the test run and the necessary chemical analysis completed in 3 work days. The test has indicated correctly the deleterious or innocuous character of approximately 70 sands, gravels, rocks a n d minerals for which mortar bar data and many service histories are available. The results of the test substantiate hypotheses developedto explain the phenomenon of the pessimum proportion and the rates of mortar expansion characteristically caused by deleterious aggregates of different types. A specific test procedure is described and is recommended for inclusion in the program of tests ordinarily applied to determine quality of concrete aggregates.