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.

Volcanic concrete is an eco-friendly concrete type in that it contains coarse and fine aggregates that all extracted from the igneous volcanic rock. However, utilizing of volcanic ash (VA) as partial/full replacement of concrete cement significantly affects the concrete workability, especially at high cement replacement ratios. This has also some adverse effects on concrete strength. Utilizing magnetized water (MW) in concrete as a partial/full replacement of ordinary tap water (TW) has a notable effect on enhancing the fresh and hardened concrete properties. This research aims to study the effect of using MW prepared in a magnetic field of 1.4 Tesla on the workability and hardened properties (compressive, tensile, and flexural strengths) of volcanic concrete. In this study, VA partially replaced volcanic concrete cement with ratios of 5%, 10%, 15%, and 20%. Ten volcanic concrete mixes were prepared in two groups. The first one was prepared with VA (0–20%) and mixed with TW. The other group was prepared with the same VA contents like group one, but mixed with MW. Microstructure imaging for volcanic concrete was also conducted in this study. Results of water tests showed 17% and 15% increase in total dissolved solids (TDS) and pH, respectively, of MW compared with those of TW. In addition, the water magnetization decreased the water surface tension by 7% compared with that of TW. Results of hardened concrete tests showed that the best ratio of VA in volcanic concrete was 5% with and without using magnetized water. The volcanic concrete slump decreased when using TW; however, using MW enhanced the volcanic concrete slump by up to 8%. The compressive strength was improved by 35%, 23%, and 20% at 7 days, 28 days, and 120 days, respectively, with no VA and with the presence of MW. The compressive strength was improved by 11%, 12%, and 11% after 7 days, 28 days, and 120 days, respectively, with using 5% VA and with the presence of MW. Both splitting tensile strength and flexural strength of volcanic concrete with and without VA or MW behaved similar to that of the corresponding compressive strength.

A major challenge in modern infrastructure is the excessive reliance on traditional Portland cement, which contributes significantly to environmental degradation and durability issues. This study addresses the need for sustainable and durable construction materials by investigating geopolymer concrete as an eco-friendly alternative, optimizing its mechanical and microstructural properties to enhance long-term performance in infrastructure applications. The performance of sustainable geopolymer concrete made with silica fume (SF) and fly ash (FA) and utilizing different alkaline activators (AAs) was examined in this study. The alkaline activators included sodium hydroxide (SH), potassium hydroxide (PH), and sodium silicate (SS) solutions. A total of twelve geopolymer concrete mixes were prepared and evaluated. The study considered several variables, including SF content (ranging from 10% to 100%), type of AA (SH+SS or PH+SS), AA concentration, and the AA to cementitious materials (AA/C) ratio. Workability, compressive strength, bending strength, tensile strength, and water absorption were among the mechanical characteristics of the concrete that were assessed, both in fresh and hardened states of the proposed concrete. The geopolymer concrete microstructure was also examined by performing X-ray diffraction (XRD), energy dispersive X-ray (EDX), and scanning electron microscopy (SEM) investigations on a few chosen mixes. The findings showed that when SF content was 10%, 20%, 30%, and 100% as a replacement of FA, the concrete slump rose by 10%, 15%, 15%, and 120%, respectively. However, the compressive strength was increased only with up to 20% SF. Geopolymer concrete with PH as the alkaline activator exhibited up to 13% lower compressive strength compared to SH. The geopolymer concrete microstructure was influenced by the presence of SF, leading to the formation of ettringite. Some FA particles that remained unreacted or were only partially reacted, along with voids, were observed. The findings from this study contribute to the development of sustainable geopolymer concrete, offering a promising solution for green structural applications.

In recent years, there has been a notable concern about the production of cementitious composites due to its high cement consumption and the corresponding carbon footprint. This has led to significant progress within the construction sector in integrating various waste materials as cement alternatives into cementitious composites. In this study, a sustainable high strength fiber reinforced mortar (HS-FRM) was designed with ceramic powder (CP) and metakaolin (MK) materials as partial replacements of the conventional HS-FRM by up to 80%. Magnetized water (MW) was used in the proposed HS-FRM as mixing water and replaced the normal tap water (TW) for producing a more sustainable and higher strength cementitious product. The HS-FRM was cured using four different curing methods, namely, tap water, seawater, air, and sunlight. Fresh, mechanical, durability, and microstructure characteristics were measured and analyzed for the proposed HS-FRM. The results showed that CP can enhance the slump of HS-FRM by up to 50% (achieved at 40% CP), while MK showed the same or less slump (by up to 33%) than that of the conventional HS-FRM. Using up to 80% of either CP or MK in the HS-FRM continuously decreased its 28-day compressive strength by up to 78% or 83%, respectively. The HS-FRM cured in tap water exhibited the highest compressive strength compared to the other curing conditions. The use of MW improved the workability of the HS-FRM by up to 225% and the compressive strength by up to 13%. The microstructure analyses interpreted the reported variation in the HS-FRM compressive strength and showed that using MW in the HS-FRM revealed a dense structure with an adequate bond between the fiber and the matrix with a relatively low number of micro-cracks and pores compared when using TW. The XRD analysis showed higher peaks of Q, C, and L with the presence of MW compared to mixtures made with TW.

In recent decades, concerns about the high cement consumption and its associated carbon footprint have prompted significant efforts in the construction sector to incorporate alternative materials into cementitious composites. This study focused on the development of a sustainable approach to produce high strength fiber reinforced cementitious mortar (HS-FRCM) and high strength fiber reinforced geopolymer mortar (HS-FRGM). The proposed mortars incorporate volcanic ash (VA) as partial replacements for conventional components, with substitution levels of up to 80%. Furthermore, magnetized water (MW) was utilized as the mixing water in producing both HS-FRCM and HS-FRGM, replacing tap water (TW) for sustainable mortars. Four different curing conditions were used; tap water, seawater, air, and sunlight. The slump values, mechanical performance, durability, and microstructural were conducted and analyzed. The results indicated that VA significantly enhanced HS-FRCM workability by up to 150%, while it had a less pronounced effect on HS-FRGM workability. When 20% VA was used, the 28-day compressive strength of HS-FRCM was not affected, but the compressive strength of HS-FRGM decreased by only 6%. The highest compressive strength was recorded for both HS-FRCM and HS-FRGM when cured in tap water, compared to other conditions of curing. Utilizing MW improved HS-FRCM and HS-FRGM workability by up to 100%, and the compressive strengths increased by as much as 15%. The microstructural analyses revealed that the use of MW resulted in a denser structure with a stronger bond between the fibers and the matrix, as well as fewer microcracks and pores, compared to mixtures prepared with TW. Fourier-transform infrared (FTIR) spectroscopy indicated the effectiveness of using VA and MW in enhancing hydration process.