Shnaihej, K.T. , Khaleel, S.F. and Sukkar, D.K.A. 2019. Preparation of Nano Silica particles by laboratory from Iraqi sand and added it to concrete to improve hardness specifications. Journal of Petroleum Research and Studies. 9, 3 (Sep. 2019), 36-58. DOI:https://doi.org/10.52716/jprs.v9i3.313.