**4. Conclusions**

The useful life of a material in place, however, is always related to the particular combination of environmental factors to which it is subjected, so that durability, or service life, must always be related to the particular conditions involved.

In the last years, the degradation of environment is more pronounced because the measures of protecting the surrounding natural places were not respected and maybe, not understood. The increase of population, the huge energy which is needed, the development of industrial processes, all these resulted in a higher consumption of natural resources, more wastes and a higher pollution [41].

New building materials have developed because the new tendencies of obtaining eco-materials and protection of natural resources [42]. There are many years since when the cement industry has incorporated significant quantities of wastes (silica fume, fly ash, blast furnace slag, metakaolin, ceramic waste, etc.) because energetic, economic and environmental protection reasons. In recent years, alternative additions - bagasse ash, bamboo leaf ash, paper sludge, have been studied as components of eco-cements. The new generation of building materials which are combined with different types of wastes can offer a possibility of consuming disposal materials and reduce the environment pollution.

Also, the development of composite construction materials with low thermal conductivity using wastes will be an interesting alternative that would solve simultaneously energy and environment concerns [43].

The concrete of any type can be obtained by adding wastes, with experimental studies and statistical optimization, which help to characterize the new materials.

The developments in building materials must be sustainable and in the same time they ensure a ratio cost-energy that satisfy the modern requirements. The addition of wastes to concrete can improve or diminish some properties of the material. Therefore, a combination of wastes is often used or other materials are introduced into the composition to compensate for any disadvantages. These materials can be fibers of different types or lengths (steel, glass, polyester, carbon, bore, textile, etc.) or nanomaterials (nanotubes of carbon, nanoargillaceous materials, etc.).

New building materials based on nano-materials will develop and will influence the con‐ struction sector. Waste can be used for producing nanopowder or other nano-products which by using new nanotechnologies allow obtaining a new generation of cement based materials, more durable, with higher mechanical properties or even with desired properties, such as electrical conductivity as well as temperature, etc [44]. Today, nanotechnologies are in preexploration stage and must find application from experimental research to applications.

Construction composite materials are developing on the base of new researches in the recycling domain as an innovative option with environmental, economic and performance benefits.
