_Applied_  
_sciences_  
_Article_  
**Evaluation of the Mechanical Properties of Normal Concrete Containing Nano-MgO under Freeze-Thaw Conditions by Evolutionary Intelligence**  
**[PERSON] \({}^{1}\)\({}^{\copyright}\)**, **[PERSON] \({}^{1}\)**, **[PERSON] \({}^{1,2}\)** and **[PERSON] \({}^{3,*}\)\({}^{\copyright}\)**  
\({}^{1}\) Department of Civil Engineering, University of Tabriz, 29 Bahman Blvd., Tabriz 5166616471, Iran;  
[EMAIL_ADDRESS] (M.Y. ); [PERSON]DDRESS] (A.F.A. ); [EMAIL_ADDRESS] (S.T.) \({}^{2}\) Engineering Faculty, Near East University, North Cyprus, 10 Mersin, Nicosia 99138, Turkey  
\({}^{3}\) Faculty of Engineering & IT, University of Technology Sydney, Ultimo, NSW 2007, Australia  
\({}^{*}\) Correspondence: [PERSON]ADDRESS]  
**Abstract** In this research, different amounts of nano-MgO were added to normal concrete samples, and the effect of these particles on the durability of the samples under freeze and thaw conditions was investigated. The compressive and tensile strength as well as the permeability of concrete containing nanoparticles were measured and compared to those of plain samples (without nanoparticles). The age of concrete samples, percentage of nanoparticles, and water-to-binder ratio are the variables of the current research. Based on the results, the addition of 1% nano-MgO to the normal concrete with a water-to-binder ratio of 0.44 can reduce the permeability up to 63% and improve the compressive and tensile strengths by 9.12% and 10.6%, respectively. Gene Expression Programming (GEP) is applied, and three formulations are derived for the prediction of mechanical properties of concrete containing nano-MgO. In this method, 80% of the dataset is used randomly for the training process and 20% is utilized for testing the formulation. The results obtained by GEP showed acceptable accuracy. normal concrete; nano-MgO; freeze and thaw durability; gene expression programming  
**1. Introduction**  
Concrete is among the most widely used materials in the construction industry owing to the ease of access to ingredients, construction in different shapes, and rapidity in operation; therefore, the life span of concrete structures is an important matter for engineers due to the economic and environmental effects of reconstruction. One of the contributing factors in the deterioration of concrete in cold regions is the repeated freeze-thaw cycles (the so-called F-T action). This repeated action causes (1) an increase in the number of micro-cracks, (2) a loss of mass, and (3) a reduction in the mechanical properties of the concrete. According to [PERSON] hydraulic pressure theory [1], the concrete is a porous material, so decreased temperature leads to the formation of ice in its pores. The formation of ice requires more volume and applies pressure to the texture of the concrete; the repetition of this action leads to the destruction of the concrete. There are several approaches to enhance the concrete performance in freeze-thaw conditions [2]: (1) using air bubbles for providing more space for ice expansion, [3,4] (2) using fillers (micro fillers and nano fillers) and pozzolans for reducing the pores such as fly ash, silica fume, nano silica, and nano MgO [5], (3) using some other mechanism by applying fibers, tubes, and sheets for the prevention of crack propagation [6], and (4) using hydrophobic materials for reducing the water absorption of concrete [7]. In the current research, the second approach is chosen by using nano-MgO, which has filler and expansive features to prevent water penetration in concrete and reduce permeability. Permenability is one of the major destructive factors for concrete. Theoretically, nano-sized particles can act as fillers, and if they are properly distributed in the concrete, they can fill nanosized pores and reduce the permeability; thereby, concrete resistivity to freeze-thaw action will enhance.