Fire Rated Concrete Wall Thickness

For example for an 8 in.

Fire rated concrete wall thickness.

The fire resistance rating of concrete masonry walls depends on the type of aggregate used in the units. A 2 hour rating can be achieved by a wall with an equivalent thickness of as little as 3 1 5 inches when expanded slag or pumice is used or 4 1 2 inches when siliceous gravel is used as the aggregate. The duration of time that an element such as beam column wall floor or roof can endure the fire which is defined in astm e 119 is termed fire rating. If the foam plastic thickness is not smaller than 25 mm r n0 59 in equation 6 is equal to 0 22.

Fire rating fire resistance of concrete masonry units is determined by the equivalent thickness of the block and the type of aggregate. Walls composed of hollow concrete masonry units having a nominal thickness of 8 inches or greater and having a fire resistance rating of at least 2 hours shall be classified as 4 hours when the hollow spaces are completely filled with perlite or vermiculite grout or a material such as expanded slag clay shale slate or sand. The fire resistance ratings of precast concrete wall panels consisting of a layer of foam plastic insulation sandwiched between two wythes of concrete shall be permitted to be determined by use of equation 7 4. Aci tms 216 1 14 code requirements for determining fire resistance of concrete and masonry construction assemblies lists the minimum equivalent thickness of single layer concrete walls to meet fire resistance ratings ranging from 1 to 4 hours see table on following page.

It is calculated by multiplying the actual thickness by the percent of solids. Fire resistance is controlled by both the physical and thermal properties of the structural element. These values are for solid walls or slabs. Foam plastic insulation with a total thickness of less than 1 inch 25 mm shall be disregarded.

51 mm thickness can be used in the joints of a 4 hour wall. Another factor to be considered in complying with fire resistive requirements is the minimum thickness of concrete cover for the reinforcement. 25 mm thickness measured perpendicular to the face of the wall of ceramic fiber in the joint can be used in walls with fire resistance ratings up to 3 hours while a 2 in. Moreover the contribution of foam plastic fire resistance is zero if its thickness is less than 25 mm.

The concrete layer thickness on each side of foam plastic should not be less than 25 mm. 13 mm a 1 in.