COMPARATIVE FIELD AND LABORATORY INVESTIGATIONS ON THE USE OF SUPPLEMENTARY CEMENTING MATERIALS TO CONTROL ALKALI-SILICA REACTION IN CONCRETE

摘要

In 1991, CANMET initiated a comparative field and laboratory research program to evaluate the effectiveness of accelerated test procedures performed in the laboratory to properly predict the long-term efficacy of supplementary cementing materials (SCM) in controlling expansion due to ASR. In that test program, air-entrained concrete mixtures were made using various proportions of fly ash and silica fume, and from which a number of test prisms, blocks and slabs were cast. The expansion of the concrete prisms stored in the laboratory (38℃ and R.H. > 95% and in 1N NaOH at 80℃) was monitored and compared to that of the larger concrete blocks (400 x 400 x 700 mm in size) and slabs (700 x 700 x 150 mm in size) cast from the same mixtures but exposed outdoors. In parallel, the various combinations selected were also tested in the ASTM C 1260 Accelerated Mortar Bar Test. The comparison of field and laboratory expansion data confirms that the use of a two-year 0.04% concrete prism expansion limit in the standard (38℃) concrete prism test is a relatively good indicator of the field performance of concrete incorporating reactive aggregates and SCM. Also, test results obtained in this study confirmed information commonly found in the literature that the modified C 1260 test generally gives a good indication of the performance of SCM to control expansion due to ASR.