Concrete Material Performance Experimental Study At Elevated Temperatures

In recent years, concrete fire problems get more and more attention with the continuous progress of China’s urbanization process. Due to the extensive application of concrete structures, and the fires can produce different degrees of damage to concrete material. This result leads to a tremendous threat to the property and life safety. The mechanical properties and durability of concrete will sharply decline at high temperature process, and the concrete spalling may be occurred at the same time. Study concrete mechanical properties change and spalling mechanism after high temperature, and take effective measures to improve the fire resistance, give useful reference to high temperature resistant and anti-spalling of concrete.The thesis is based on concrete material mechanical properties and spalling mechanism at high temperatures as a research target. The main content includes the following aspects:1. Study color, fineness modulus, average particle size, particle distribution, crushing index changes of heated concrete aggregates, and prove the impact of temperatures on concrete aggregates, and explore heated aggregates make a difference to mechanical properties of mortar and concrete at elevated temperatures.2. Heated aggregates are prepared mortar and concrete block, and then take mortar and concrete blocks heating tests to explore compressive strength, splitting strength, and reflect the effect on the mechanical performance.3. Take concrete high temperature spalling experiments to explore the relationship between temperatures and vapor pressure with standard size cubes; through high temperature heating process, take a statistics and analysis of high temperature damage phenomena; manual hydraulic test pump experiment gives a indirect proof to vapor pressure mechanism.4. Ansys is used to get temperature field and thermal-structure coupling analysis, and simulate temperature distribution and compressive failure of mortar and concrete block, compared simulation results with experimental values, in order to verify the validity of the experimental results.Through experimental results and simulation analysis, reasonably evaluate concrete mechanical properties after high temperature, and assess concrete fire-resistant design and risk analysis, also provide anti-spalling theoretical basis.