Source: ASTM International, West Conshohocken, Pa.
ASTM Subcommittee C09.20 on Normal Weight Aggregates, part of Committee C09 on Concrete and Concrete Aggregates, is developing a standard to distinguish between harmful and non-harmful fines in construction aggregate.
Ready mixed, aggregate and asphalt producers will use the ASTM WK36804 Test Method for Rapid Determination of the Methylene Blue Value for Fine Aggregate and Mineral Filler to qualify new material sources and in routine quality control procedures. The proposed standard entails a method that can be performed in the field in about 10 minutes and does not involve the titration and visual assessments typically associated with such testing.
“The methylene blue test has been shown to be an effective indicator of the amount and type of clay present in aggregate and can therefore help to distinguish between harmful and beneficial fines,” says C09.20 member and W.R. Grace and Co. Research & Development Director Eric Koehler. “Once it has been approved, the proposed standard will enable the use of a wider range of sands and limestone fillers in concrete, while also ensuring that these aggregates are of high quality. This will prevent the waste of non-detrimental fines, which must currently be washed out of sand indiscriminately, [and] result in more sustainable use of limited aggregate resources.”