American Petrographic Services Inc.

APS > Services >Aggregate >Alkali-Silica Reactivity (ASR)

Aggregate Alkali-Silica Reactivity (ASR) testing represents an integral part of ongoing laboratory testing services at American Petrographic Services, Inc. (APS) and American Engineering Testing, Inc. (AET). As the only laboratory in the Upper Midwest to be accredited by the American Association for Laboratory Accreditation (A2LA), meeting the requirements of ISO 17025, General Requirements of Competence for Testing and Calibration Laboratories, we can test for this important parameter using any of seven accepted methods.

The following table details our scope of services for ASR testing:

Test method	Name of test	Completion time	Sample size (lbs.)
ASTM:C1260*	Potential alkali reactivity of aggregates (Rapid Mortar Bar Method)	3 - 4 weeks	10# Aggregate 3# Cementitious (of each size & source)
ASTM:C1293	Length change of concrete due to alkali-silica reaction	12 months minimum	125# Aggregate 50# Cementitious
ASTM:C227*	Potential alkali reactivity of cement-aggregates combinations (Original Mortar Bar Method)	6 months	15# Aggregate 5# Cementitious (of each size & source)
ASTM:C289	Potential alkali-silica reactivity of aggregates (Chemical Method)	3 - 4 weeks	5# Aggregate
ASTM:C295*	Petrographic examination of aggregates for concrete	2 - 4 weeks	5# Fine aggregate 30# Coarse aggregate (of each size & source)
ASTM:C856*	Petrographic examination of hardened concrete	2 - 3 weeks Rush: add 20%	Cylinder or chunk (full depth)
ASTM:C441	Effectiveness of mineral admixture in controlling alkali-silica reactivity	6 months	10# Aggregate 5# Cementitious

*A2LA-accredited test method

ASR is the reaction between unstable silica in aggregates and the alkali in the cement paste, which produces an expansive gel. This reaction causes extensive cracking and expansion within the aggregate particles and ultimately damages the concrete itself. Common reactive aggregates include chert and shale as well as igneous and metamorphic rocks containing strained quartz. As these reactions are driven by moisture, reactive aggregates used in exterior construction are typically the most susceptible. The reaction continues as long as reactive silica and moisture are available.

To avoid ASR issues, fine and coarse aggregates are tested in concert with a high alkali cement. For specific projects, testing may be performed with the actual materials proposed for the new construction. Representative testing in early stages can minimize problems in the future.

Additional lab and field services are available.

While ASRgel is extruding from an extensively cracked concrete rail.

While ASRgel fills micro cracks, proceeds through a reactiv coarse aggregate particle.

A length comparator measures length change in a mortar bar undergoing ASR potential testing.