(CS3.1) Architectural concrete vulnerability and climate change: I.M. Pei’s National Center for Atmospheric Research (NCAR) and the Everson Museum of Art

Reinforced architectural concrete gave rise to a myriad of spectacular architectural forms and expressions in the 20th century. However, as modern heritage buildings age, the vulnerabilities of reinforced concrete have become more urgent in the anthropogenic era. The changing climatic factors are, and will, continue affecting concrete deterioration. Freeze-thaw and wet-dry cycles result in observable surface recession; the increasing carbon dioxide concentration in the atmosphere results a changing rate of concrete carbonation, and onset of reinforcement corrosion. Both deterioration mechanisms are concealed from view until the concrete is damaged.

This presentation will discuss climate change impact, surface recession, and carbonation of bush-hammered concrete in I.M. Pei’s the National Center for Atmospheric Research (NCAR, 1961-1967) and the Everson Museum (1961-1968). NCAR and the Everson Museum are essentially two contemporaneous projects by I. M. Pei, designed with alike intents and construction techniques: both feature cast-in-place concrete with site-specific mix designs. Their walls feature a patterned bush-hammered concrete surface on the exterior (NCAR and Everson Museum) and interior (Everson Museum). This is a technique that removes the freshly hardened concrete surface to expose the underlying aggregates, sand, and pores.

The location of these two highly similar structures in two different climate zones provides the opportunity to (1) evaluate surface recession rates since their constructions, (2) predict carbonation rates considering changing climatic variables using available carbonation model and climate projection from 1967-2099, and (3) highlight the combined effects of these factors in the changing climate.

This presentation will emphasize the importance of monitoring surface recession and carbonation depth in the conservation of significant concrete buildings with bush-hammered surfaces, as well as the development of predictive models.