4.4. Alkali-Silicate Reaction (ASR) Studies
ASR results in the formation of alkali/silica gel, which expands and causes significant
material damage. The gel is formed due to the reaction between cement alkalis and a
reactive form of silica from aggregates or supplementary additions. FHWA researchers
are using neutron scattering and positron annihilation spectroscopy to measure nano-scale
changes in gel microstructure as a function of gel chemistry, temperature and relative
humidity