High-strength concrete was gradually developed through the years. Early in 1950, concrete with 34 MPa was considered as high strength concrete. In the sixties of the last century, concrete with 62 MPa was considered high-strength concrete. These days, concrete with 55MPa compressive strength or greater is defined as high-strength concrete (HSC) depending on ACI363 R-10 2010 [1]. HSC consists of cement, cementitious material, and aggregate, water and superplasticizers. When these contents are proportional and mixed very well, it is possible to have compressive strength reach 140 MPa or slightly greater [2].
To produce HSC, the raw material must be of high quality and optimal mixing ratio. Besides that, reducing the W/B ratio by using a superplasticizer is the most important factor in gaining high strength. [3]. Reducing consumption of potable water is necessary due to increasing population growth. Magnetic treatment technology was used to improve the molecular structure of water, thus saving quantities of water, especially used in concrete production [4]. For improving concrete mechanical properties, water treatment with a magnetic field technique was used. This technique used by the Chinese and Russians, using magnetic water in concrete mixing leads to improved workability and compressive strength and reducing the cement content 28% in the mixture may reduce environmental pollution [5]. The compressive strength of concrete with magnetic water increased by magnetic strength increase. Where increasing magnetic strength means increasing treatment water for cement hydration thus increasing the efficiency of the cement mixture in concrete [6]. Much research done on using magnetic fields in the concrete mixture such [7] found that magnetic water improves the fluidity of cement paste and increases cement hydration leading to accelerating hardening time. Soto-Bernal[8] study the effect of three magnetic intensities (25.37, 22.22, 9.07), Gauss, on cement paste and found that the microscopic environment of cement pastes would change in terms of the shape and quantity of CSH, where CSH quantity increase with increasing magnetic intensity.
Muthu Prakash[9] found using magnetic water to produce concrete leads to reduced water content and raised the compressive strength by 15%. Magnetic water can solve many environmental problems by treating industrial wastewater with a magnetic field and using it in concrete, as it gives strength similar to the strength resulting from the use of ordinary water. When mixing concrete components with magnetized water, it improves the mass density, compressive strength [10].
Nan Su in 2002[11] concluded concrete compressive strength increased with increasing magnetic intensity played on a mixture of water, and this increment happened at an early age while at a late age, the compressive strength was similar to this without magnetic water and this conclusion was confirmed by [12].
To have a better understanding of how water affects strength, a close look at its molecular structure was done. Water’s molecular content has two hydrogen atoms and one oxygen atom connected by a covalent bond at an angle of 105°. Since the oxygen’s atom is negative and the hydrogen’s atoms are positive, they tend to be attracted to each other and produce large accumulative groups. To break these accumulative molecular groups, much research has been done on the effectiveness of magnetic fields on water (magnetic water) [13]. When water passes through a magnetic field, the bond’s angle would be shrinks and the water molecules arranged in one direction Figs. 1 & 2.
Also, the magnetic field that is applied to water could reduce the attachment of hydrogen bonds so the large molecular water groups break into small groups maybe 2H2O or even 1H2O [15]. The physical properties of water changed after its exposure to the magnetic field reducing both boiling temperature and specific heat and increasing the amount of evaporation. All of these changes depend on the effect of magnetization involving the strength of the magnetic field [16] and [17].In addition, the magnetic field affects PH, the amount of ions, and the solubility of salts in water by increasing the PH and reducing salts which leads to corrosion rate reduction [18].
Most of the previous studies studied the effect of magnetized water on the properties of concrete. In this study, the effect of magnetic treatment of the concrete mixture on the properties of high-strength concrete was studied.