Polymers render concrete fire-resistantSelf-compacting and now fire-proof, tooSelf-compacting high-p
Polymers render concrete fire-resistantSelf-compacting and now fire-proof, tooSelf-compacting high-performance concrete (SCHPC) has till now suffered from one weakness: when exposed to fire it flakes and splits, which reduces its loadbearing capacity. Empa scientists have now developed a method of manufacturing fire-resistant self-compacting high-performance concrete which maintains its mechanical integrity under these conditions.Wood crackles as it burns in a chimney or campfire. When concrete is exposed to fire it chips and flakes – a process known as spalling. Both effects are due to the same phenomenon: water trapped within the piece of wood or concrete element vaporizes due to the high temperature. As more water vapour is produced the pressure within the wood or concrete structure increases. In wood this causes the cells to burst with a crackling sound, creating cracks in the logs. In concrete structures, chips split away from ceilings, walls, and supporting pillars, reducing their loadbearing capacity and increasing the risk of collapse in a burning building.The resistance of conventional vibrated concrete to the heat of a fire can be optimized by adding a few kilograms of polypropylene (PP) fiber per cubic meter of concrete mixture. When exposed to fire the fibers melt, creating a network of fine canals throughout the concrete structure. These allow the water vapour to escape without increasing the internal pressure, so the concrete structure remains intact.Read more. -- source link
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