What is the maximum compressive strength requirement of concrete?

Concrete compressive strength requirements can vary widely based on the specific application, structural demands, and design criteria set forth in various codes and standards. Therefore, stating that there is "no maximum unless specified" aligns with how concrete is designed for different uses.

In many construction projects, while there are minimum strength requirements to ensure the appropriate structural integrity, the upper limits can be left open depending on the project's needs. For instance, specialized structures, high-rise buildings, or certain infrastructure projects may require concrete with strengths well above 5,000 psi, 10,000 psi, or even 15,000 psi, depending on the use cases and engineering specifications.

Options that present a fixed maximum strength do not accommodate the flexibility and variety that engineers have when designing concrete mixes to meet specific challenges and conditions. This prominence of custom concrete design practices supports the conclusion that without explicit limitations imposed by the project requirements or governing codes, there isn't a universally applied maximum compressive strength for concrete.