Nano technology is increasingly being used in concrete industry, and in particular the use of nano silica particles in cementitious materials is becoming more popular to improver concrete properties. This paper deals with studying the influence of replacing a portion of cement by either nano silica, micro silica, or a combination of both on the strength properties (compression, tension and abrasion) of the cementitious mortars produced. Micro-silica particles are altered from 0, 5 and 10% while nano-silica particles are altered from 0, 0.5 and 1.0%. The paper reveals the method of mixing nano particles to prevent agglomeration and achieve a homogeneous mix so that the nano particles are well dispersed throughout the mortar matrix. Results indicate that incorporating both micro or nano particles improve the mortar matrix by making it denser with less internal voids hence preventing any transport of liquids throughout its matrix. In addition to the pozzolanic effect caused by using micro silica and nano silica which increases mechanical properties of the cement mortars.