Glass Fiber Reinforced Concrete Panel Cracking at Office Complex
An office complex located in Tempe, AZ comprises five buildings that were constructed between 1998 and 2000. Four of these buildings are three-story structures that originally incorporated glass fiber reinforced concrete (GFRC) exterior cladding. Shortly after completion, several GFRC cladding panel skin sections began exhibiting cracking in the exposed aggregate face mix finish. Water leakage through some panels was also noted.
The Owner hired CTLGroup to investigate the cause of the panel cracking and leakage, and provide opinions related to proposed rehabilitation strategies.
The scope of CTLGroup’s investigation included document review, close-up inspection of panel surfaces, water testing, thermal monitoring, thickness surveys, material sample extraction, material property testing and structural analysis. Inspections performed over consecutive years revealed that a significant number of panels had developed visible cracking, and that the extent of cracking is progressing with time. Water tests confirmed the panel cracks as the source of leakage to the building interior. Thermal monitoring studies were performed to measure maximum panel skin temperatures and through-thickness gradients for use in subsequent structural analyses. Interior inspections and material studies were conducted to determine as-built panel conditions and properties.
Findings from the investigation revealed that volume change movement incompatibility between panel skin component materials, and certain as-built anomalies/defects, contributed to the causation of cracking. It was also determined that additional cracking would likely continue to occur due to expected GFRC material strength reduction with age.
Based on these findings, a decision was made to remove and replace the GFRC panel skin. CTLGroup’s expertise helped the building/facility owner evaluate the cause and long-term consequences of the building envelop issue having significant effect on operations, and helped them manage the problem until a timely resolution was achieved.