The effect of dye and metals salts on white cement curing and properties of decorative wood wool-cement composite

The use of new materials with competitive features in the construction industry has always been considered. The stage of finishing and interior decoration is also considered an important part of this dynamic industry, which is closely related to the wood products industry. In this study, the optimal conditions for making decorative wood wool cement board were investigated. The aim of this study was to investigate the effect of water-based paint on the hardening of white cement and improve the quality of the bonding in this decorative panel using metal salts.

The wood wool were first pretreated with hot salty water to remove the inhabitant compounds. For this purpose, the wood wool piles are mixed with white cement, accelerator (sodium chloride and calcium chloride), water and plastic paint in a certain ratio and after manual forming were placed in cold press for 20 minutes for initial compression. Then for initial setting of cement and reaching a thickness of 16 mm, it was placed in a secondary cold press for 18 hours. After leaving the cold press, the produced panels were conditioned for 28 days in order to completely setting the cement. Then their physical and mechanical properties were measured according to the relevant standards.

The results of this study showed that the best mechanical properties were related to panels made with calcium chloride and in these conditions the highest modulus of elasticity (MOE) was related to calcium chloride with a level of 5% equal to 1217.9 MPa. In case of flexural strength (MOR) and internal bonding (IB), the highest results were observed in treatments with 3% Calcium chloride and was equal to 3.7 and 0.15 MPa, respectively. Also, the optimal conditions for improving the physical properties were determined by applying sodium chloride at the level of 5%, in that the water absorption (WA) and thickness swelling (TS) were determined 7.9% and 0.43% respectively.

By adding the paint to production process of wood wool cement board, the curing time was increased and caused reduction in some properties. But with adding metal salts, the curing rate was improved and the reduction in almost properties was compensated. Salt type had significant influence on properties like MOE, IB, WA24h and TS24hvwhile the effect of salt amount was only significant on MOE and WA24h. Regarding to the variety of application and special characteristics of WWCB, including sound absorption, dimensional stability, fire resistance, abundance and cheapness of raw materials, no complexity of the production process, no emission of toxic compounds such as formaldehyde, it could be suitable choice for decorative purposes in building industries.