Lately, I speak to many people who use dragline mats. This gives me a good picture of the experiences gained with the existing crane mats.
The current crane mats are made of tropical hardwood. Azobé is a very common material, but due to the high demand in the slow growth of these trees, the quality of these deteriorates rapidly. More and more young trees are being cut down, often from protected areas. As an alternative, softer woods are used. In a standard crane mat, the outer beams are often made of the hard Azobé and the inner beams of a softer type of wood.
The effect of this is that the inner beams wear faster and cause a cavity. Another effect is that the softer beams are less resistant to water and will eventually rot. This of course does not benefit the overall strength and stiffness of the crane mat.
A better alternative is the use of bamboo composite. With this, the strength is not lost and the resistance to water, and with it rotting, is many times greater.
Bamboo composite has been used for years along the water in the form of scaffolding. It is exposed to water intensively and remains free of rot for up to 30 years. This proves that it is an excellent material for the crane mats.