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1. Workmanship (Cement boards, fire stop, protected/exposed cables) Double layer fire protection to beams and slabs were provided in all tests
with POP sheets and cement boards. In Test 1, 18mm thick cement boards
Structural fire protection protects essential structural components from were fixed to MS square pipe section at 8’’ c/c, whereas in Test 2, 12mm
Part III direct fire exposure. This is accomplished with fire proofing materials like cement boards were used fixed with SDS screws at 20’’ c/c. In Test 1,
intumescent paints on cables, endothermic materials like gypsum-based cement boards performed better and prevented POP sheets to be
COMPARISONS, plasters and cementitious products, mineral wool as fire stop insulation, etc. exposed to fire thereby protecting the deck slab. Local failure of cement
boards was detected at all levels but complete failure was not observed
The workmanship during such structural fire protection is important and of
INFERENCES AND major concern. (refer Image 42). In Test 2, premature failure of cement boards was
observed due to greater spacing between SDS screws and reduced
RECOMMENDATIONS thickness of boards. Complete failure of cement boards was observed
which led to failure of POP sheets and exposing the deck slab to direct
exposure of fire (refer Image 43). Distortion of deck slab was also
observed due to poor performance of cement boards. Thus,
workmanship during fixing of fire protection in form of gypsum and
cement boards becomes of prime interest.
Image 43: Complete failure of cement boards at ground level after fire test 2
Fire stopping serves as an important link in prevention of fire and smoke
from one floor level to another. Workmanship during installation of fire
stop material is of major concern. Fire Tests 1, 2 and 3 were conducted with
a specific density of glass wool, typically in the range of 4-8 pcf, but most
often at the high end of that range, due to the superior thermal
properties of the higher density material. The higher density material is
admittedly more difficult to work with, as it is compressed, cut or shaped
less easily. Also, lower density glass wool (i.e. 4 pounds per cubic foot) is
more commonly used on construction sites for other purposes. The result
is that lower density glass wool is sometimes improperly substituted for
greater density wool (i.e. 8 pcf) in cases where the tested system requires
the greater density wool. Using the wrong (lower) density wool can cause
the firestop system to fail much earlier than the desired duration, thus
creating a significant weak point in the floor or wall. This reinforces the
concept that the firestop system must be installed exactly according to its
Image 42: Cement boards held intact (local failure) at ground level after fire test 1 listings to help ensure proper performance.
