Hi, dear Dr. Jabbar

You know that concrete is a heterogeneous material and it is not easy to make it very watertight due to the presence of the various phases. However, reducing w/c and using the micro and nano materials as a cement replacement can produce concrete with a dense microstructure. Again, this action can retard the water diffusion, and consequently, increase the concrete service life but cannot prevent the water entrance completely. The packing effect (in addition to the pozzolanic reaction) among cement, micro silica, and nano-silica may be considered as a successful method, but it needs to be experimentally performed to test its efficiency.