4.1 Common types of SCM include fly ash, slag cement, calcined clays, and silica fume. The introduction and widespread use of fly ash, slag cement, calcined clay, and silica fume have been characterized and supported by significant research and development programs, preconstruction testing, field testing and long term performance monitoring. As the technical and economic benefits of SCM have been recognized, and as sustainability and environmental awareness resulted in the need to develop new materials and new ways to use materials not previously utilized, new sources of potential SCM are being proposed for use in concrete as ASCM.

4.2 If an ASCM does not yet have a significant record of performance in concrete, a comprehensive evaluation based on this Guide should be undertaken, and it should be recognized that this ASCM might be introduced for a specific project or into a limited marketplace to initially demonstrate its performance. The user should bear in mind the intended end use of the ASCM and use appropriate test methods to establish its suitability. An ASCM that demonstrates good performance through a comprehensive evaluation as outlined in this guide could then be considered to have access to broader markets and could be considered for inclusion in an ASTM standard for SCM. For this reason, the test program to demonstrate acceptable performance should include concrete mixtures with a range of characteristics specific to the ASCM's intended use.

4.3 In the absence of long-term durability or acceptable field performance, prospective users are advised to apply appropriate risk management and engineering practice in the use of an ASCM.