What is the biggest drawback of the cast-in-place reinforced concrete structure building?

The reinforced concrete structure has the following major shortcomings:
(1) Since the material. The density of gravity of the reinforced concrete is approximately 25kN / m ^ 3, severe than masonry and wood. Although severe than steel, but the larger the cross-sectional dimension of the structure, and thus its own weight far exceeds the same span or height of the weight of steel.
(2) poor crack resistance. As mentioned earlier, the tensile strength of the concrete is very low, therefore, ordinary reinforced concrete structure with cracks frequently. Although the presence of the cracks does not necessarily mean that a structure is destroyed, but it affects the durability and aesthetics of the structure. When the cracks in larger quantities and to carry out a wide, also inflicts a sense of insecurity. (3) the nature brittle. Increase the brittleness of concrete with the improvement of concrete strength grade. In summary is not difficult to see that the reinforced concrete structure strengths outweigh its shortcomings. Moreover, people have developed many effective measures to overcome its shortcomings. For example, in order to overcome the major drawback of reinforced concrete since have developed a lot of light weight, high strength concrete and high strength steel. In order to overcome the shortcomings of ordinary reinforced concrete is susceptible to cracking, prestress it. In order to overcome the brittleness of concrete, concrete mixed fibers made ​​of fiber reinforced concrete.