Development of the Fire-Resistant Mortar from Reused Polyurethane Foam

Polyurethane (PU) foam is widely used for thermal insulation applications e.g. building
and refrigeration. PU foam also shows a characteristic of fire retardant, thus make it difficult to
incinerate. This study aims to reuse the waste PU foam from refrigerators by mixing with
cement to create fire-resistant masonry cement (plaster cement). The mortar mixture consists of
PU foam with a diameter less than 2 mm, cement, sand, and water in different portions. The PU
foam is used to replace the sand portion. All cement mixtures must conform to the ASTM C91
standard for masonry cement. All mixtures show the flow testing range of 110±5 cm. The
compressive strength testing of the cement after a 7-day and 28-day curing period showed a
minimum compressive strength of 3.7 and 6.2 MPa, respectively. All mixtures at 36 °C
conformed to these strengths. Subsequently, the compressive strength of the mortar after
exposure to the temperatures at 600 °C for 3 hours showed that the non-foam, 25%, and 50%
substituted foam for sand still conformed to ASTM C91. The thermal conductivity of the
developed cements decreased when the foam content increased. The mortar with 25% substituted
foam to sand was the appropriate ratio that showed the characteristics of fire resistance and low
thermal conductivity and conformed to the standard for compressive strength.
Keywords: Fire Resistant Masonry Cement / Polyurethane Foam