Characterization of nano-silica prepared from local silica sand and its application in cement mortar using optimization technique

Abstract The objective of this work is to prepare, and characterize silica nanoparticles (NS) for the first time from Ardma silica sand, which is obtained from Anbar province in the west of Iraq. The procedure suggests using a combination of ball milling and heating process, then evaluating the influence of (NS) addition on mechanical properties (compressive strength and splitting tensile strength) of mortar mixture to improve its characteristics. Optimization of the operating variables (nanosilica particle size, and percentage of addition) involved using (WinQSB) and (Statistica) software to predict the optimum conditions. Samples have good SiO 2 value of about 99.2% increased up to 99.83% after leaching with sulfuric acid. The high purity silica sand was milled for 30–50 h to produce nanoparticle silica with average particle size of 50 nm. By means of TEM, SEM, AFM, and PSA characterization, these nanoparticles look like spherical particles and have irregular shapes with clusters, the range of their external diameters is (30–100) nm. These nanoparticles silica have a good possibility to be applied as an additive material to produce ultra high performance concrete. According to our knowledge, there is no previous work focusing on preparing of silica nanoparticles from Ardama silica sand, and used to improve mechanical properties of cement mortar using optimization technique. Optimization results proved that an improvement in compressive strength of 29.889% occurred under optimum conditions (6% adding percent and 50 nm particle size), while tensile strength was 22.863% under optimum conditions (8% adding percent and 50 nm particle size) at 28 day age.