Manufacture of lignocellulosic fiber–cement boards containing foaming agent

Combination of chemical foaming and air curing process is an alternative to produce fiber–cement boards out of Equisetum (Eq. telmateia) fibers and cement which would have low thermal conductivity and acceptable mechanical and physical properties. This study was conducted to determine the suitability of Equisetum fibers, silica fume gel (SFG) and micro aluminium powder as foaming agent (AL) to manufacture structural composite boards with target density and thickness of 1.10 g/cm3 and 13 mm, respectively. In these experimental boards macropores were created by adding AL as a chemical foaming agent; moreover, amount of cement in mixture has been optimized by specific amounts of SFG and Equisetum fibers. All boards were tested for their thermal conductivity, physical and mechanical properties according to specification JIS standards, and influences of additives on properties of produced fiber–cement boards were investigated as well. Results have revealed that mechanical properties of fiber–cement boards were improved by increasing Equisetum fibers and SFG contents whereas thermal conductivity did decrease. By increasing AL, both mechanical strengths and thermal conductivity were decreased. With regard to the physical properties, AL has led to increase in water absorption; however, SFG has deceased mentioned property. In general, comparison of these experimental boards with commercial composite boards in terms of measured properties confirms these composite boards as low thermal conductivity materials which are extremely desired for energy saving be used as ceiling and wall constructing material. In addition, physical and mechanical properties of such composites meet international standards.