In this study, fourteen sustainable concrete mixes containing metakaolin (MK) as supplementary cement material (SCM) and magnetized water (MW) as concrete mixing water were designed, prepared, tested, analyzed, and compared. The MK was used as a partial replacement of cement weight by 5%, 10%, and 20%, and as an additive to cement by 5%, 10%, and 20% of cement weight. The MW was used to fully replace tap water (TW) in concrete mixes and was prepared using two different magnetic fields of 1.4 tesla (T) and 1.6 T. This experimental research aimed to assess the characteristics of concrete manufactured with MK and MW. The mechanical and durability characteristics of fresh and hardened concrete were measured for the assessment. Microstructural and chemical analyses were carried out on selected materials and concrete mixes. The workability and compressive strength of the materials at 7, 28, and 365 days were measured, in addition to the splitting tensile strength at 28 days and the flexural strength at 28 days. The compressive strength at 365 days was conducted at 18 °C and 100 °C to study the effect of the applied variables on the concrete durability at different elevated temperatures. The microstructural and chemical analyses were conducted using a scanning electron microscope (SEM), energy dispersive X-ray (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results showed that using 10% MK as a cement additive was the best ratio in this study, which enhanced all the measured mechanical characteristics when the TW or MW was used. Using MW instead of TW in MK concrete increased all the mechanical properties measured at 28 days by about 32–35%. The results of the microstructural and chemical analyses supported the compressive strength increase by showing indications of more C-S-H gel production and less CH when using MW in MK concrete. In addition, fewer micro-cracks and pores, and relatively denser concrete, were detected when using MW with 10% MK as a cement additive.

Using metakaolin (MK) in concrete with magnetized water (MW) has a high possibility to enhance concrete suitability. In this study, the effect of using MK and MW on concrete characteristics was studied through testing twelve concrete mixes. Seven ratios of MK were used in this study, namely 0%, 5%, 10%, and 20%, as an alternative to cement and +5%, +10%, and +20% as a cement additive. In addition, five water magnetization methods were applied on MK concrete. In the first stage of this study, the impact of different MK ratios on the workability of concrete, compressive strength, flexural strength, and tensile strength was studied using traditional tap water (TW) as the concrete mixing water. In the second stage, the best mix (best MK ratio) from the first stage was chosen to study the effect of the water magnetization method on concrete properties and to determine the best method for water magnetization. Scanning electronic microscope (SEM) analysis was also carried out on selected mixes to closely investigate the effect of MK and MW on concrete microstructure. The results showed that the best ratio of MK in concrete was +10% (MK as a 10% cement addition), and the best water magnetization method was to pass the water through 1.6 tesla then through 1.4 tesla magnetic fields. The SEM analysis confirmed the absence of pores after using MW instead of regular TW by increasing the calcium silicate hydrate (CSH) gel and reducing calcium hydroxide (CH). Using MK and MW enhanced the compressive strength by up to 33%, 32%, and 27% at 7, 28, and 365 days, respectively, and MW enhanced the workability by up to 3% compared to that of the control mix.