# Selected Properties of Overlaid Magnesium Based Composite Panels for Flooring
## 1 Introduction  
Flooring manufactured from solid wood is the most expensive and desired for interior applications among the other materials in residential buildings [1]. Homes with solid wood flooring would be expected to have higher resale value than comparable homes with non-wood floors. The overall value of flooring in construction industry in the USA was about $2 billion and $5.8 billion in 2009 and 2014, respectively [2]. It is expected that such values will increase over the next two decades with newly developed residential areas due the high rate of the urbanization in the US [2]. Although solid wood is considered as prime product in flooring manufacture, its dimensional stability and high cost are some of the major disadvantages. Therefore there has been great trend over the last several decades shifting from solid wood to engineered composite flooring in the industry not only from the point of cost but also being environmentally friendly. Typical engineered flooring panels consist of several thin layers of wood veneers of various species constructed similar to plywood being more functional and less expensive than solid wood flooring [1; 2; 3; 4]. Dimensional movement of such flooring due to moisture content fluctuation in surrounding environment is very minimal having cross grain orientation of each ply in the member. Consequently they are more stable than solid wood flooring with minimum changes in their dimensions as their moisture content values change. Oak, maple, ash, birch, cherry, and beech are the most commonly used species to manufacture solid wood and engineered wood floorings [1; 5]. Overall solid wood flooring market has been changing due to its cost in the form of development of laminated flooring which has been widely used in many countries in the last 30 years. [1; 2]. Generally laminated flooring is constructed from various layers of elements which are bonded together in the form of a sandwich configuration. High density fiberboard is a composite panel produced from mostly wood waste within the scope of sustainable approach to save overall forest resources. Laminated flooring manufactured from high density fiberboard (HDF) is definitely less expensive than other types of engineered wood flooring [2; 6]. Direct pressure lamination is produced by having melamine wear resistance protective finish as the top layer, high decorative print paper with different color and patterns, HDF panel as the core layer and balancing melamine as the backing layer. The main purpose of such construction is to provide dimensional stability to the units [5]. High pressure laminate (HPL) which is also used for flooring has one or two more layers than that of direct pressure lamination (DPL). Assembled panels are compressed using a pressure of 8.5 MPa at an approximate temperature of 160 \({}^{\circ}\)C for 30-40 s. Following the conditioning of the panels they are cut into planks for further processes [1]. Aluminum oxide particles in combination with melamine resin resulting in scratch resistance of the finished product are used as a top wear layer which makes it harder than many solid wood species. Such flooring can be installed in kithens, bathrooms and other places with high relative humidity but being a hygroscopic material they do not tolerate direct contact of water for long periods of time similar to other wood based floorings. Solid wood flooring has natural irregular grain orientation unlike to engineered floorings or laminate flooring with uniform and homogeneous grain pattern. High pressure laminate flooring is manufactured tongue and groove so that adjacent pieces are interlocked with each other resulting in a solid paneling effect on the floor. Laminated flooring units manufactured from composite panels still have their limitations of high production cost therefore new raw materials are constantly being developed by the producers. Linoleum and magnesium oxide known as magnesia are two raw materials used as a constructional products including drywall.