A Preliminary study on the use of magnetic, Zamzam, and sea water as mixing water for alkali-activated slag pastes

Alrefaei Y., Wang Y., Dai J.

This paper investigates the effect of using different admixtures on the one-part ambient-cured alkali activated pastes. Na2SiO3-Anhydrous powder was used as solid activator along with three superplasticizers including naphthalene, melamine and polycarboxylate with different water/precursor ratios. The flowability, setting time and compressive strength development were evaluated for all AAMs mixes. ATR-FTIR test was used to check the admixtures stability in high alkali media. All types of admixtures significantly improved the flowability of the Na2SiO3-anhydrous one-part AAMs and marginally affected the compressive strength. The results showed that polycarboxylate was effective for high water/precursor (≥0.36) while naphthalene performed better in case of low water/precursor (≤0.36) for Na2SiO3-anhydrous one-part AAMs. However, lowering the water/precursor ratio in the Na2SiO3-anhydrous one-part AAMs using superplasticizers showed no improvement or modest improvement in the compressive strength. The ATR-FTIR results revealed the relatively high stability of admixtures in Na2SiO3 alkali medium of one-part AAMs (for w/b = 0.4).

Rashad A.M.

Geopolymer is an innovative material and a real alternative to traditional Portland cement for use in the construction industry. Incorporation of the use of geopolymers in civil engineering is one of the most-promising options for reducing environmental impact and the huge energy consumption of Portland cement manufacture. Since geopolymers were discovered, further development has produced more modified, strong, durable and sustainable binders. One option to develop and modify some properties of this system is to add other prospective materials such as nanoparticles. In general, the applications and advances of nanotechnology in geopolymer materials remain limited in comparison with those of traditional cementitious materials. However, in the last few years, the effect of nanoparticles on the properties of geopolymers has been given increased attention. This article presents an overview of earlier studies focused on adding different types of nanoparticles, such as nano-silicone dioxide (SiO2), nano-titanium dioxide (TiO2), nano-aluminium oxide (Al2O3), nano-clay and geothermal nanosilica waste, into different geopolymer matrices. Fresh and hardened properties have been reviewed and briefed. The current review can be used as a guide to know what has already been covered in the research and what should be covered in future studies.

Kim T.

In this study, an experimental investigation of the mechanical properties of alkali-activated slag cement (AASC) mixed with polyaluminum chloride (PAC) was conducted. The alkali activators were 5% sodium hydroxide and 5% sodium silicate of binder weight. The PAC substitution rate was varied by adjusting the mixing water weight from 0% to 10%, and the obtained samples were characterized by test for compressive strength, X-ray diffractometry, scanning electron microscopy (SEM), mercury intrusion porosimetry, thermogravimetric analysis, differential thermal analysis, and energy-dispersive X-ray spectroscopy. PAC substitution formed a dense C-A-S-H gel and Friedel's salt. SEM observations revealed that a dense matrix of hydration products and Friedel's salt existed in the pores. Moreover, greater amounts of PAC result in better mechanical performance. Thus, these hydration products enhance the strength of AASC by compacting the matrix and filling the voids.

Bondar D., Ma Q., Soutsos M., Basheer M., Provis J.L., Nanukuttan S.

Ground granulated blast furnace slag (GGBS) is the most common industrial by-product used as a precursor for alkali activated binders due to its fast setting, simple curing needs, and good early age strength gain. There are conflicting findings on the chloride penetration resistance of such binders and more information is required regarding the suitability of this type of binder material for chloride environments. This article outlines the findings of investigation of alkali activated slag concretes (AASC), to provide a comprehensive view of the effect of mix design variables on slump, strength, and chloride transport and binding. It is concluded that AASC can be designed for different workability and different grades of concrete. The diffusivity results demonstrate that the addition of excess water does not directly control the pore structure/connectivity in AASC as it does for Portland cement, and therefore AASC can be designed based on the water/binder ratio needed for a specified mechanical performance. The chloride binding capacity increased as the paste content of the concrete and/or the silica content of the activator was increased.

Rashad A.M.

Yu C., Wu Q., Yang J.

This paper aims to study the effect of seawater mixing on the properties of potassium magnesium phosphate cement (MKPC) paste. Fresh water and seawater were used to prepare MKPC pastes, respectively. Then, the compressive strength, residual ratio of compressive strength, hydration temperature, phase composition and microstructure of the MKPCs prepared with seawater and fresh water were compared. Results showed that the MKPC pastes prepared with seawater had higher fluidity, longer initial setting time and lower compressive strength than those prepared with fresh water. Adding silica fume and limestone powders to MKPC pastes prepared with seawater can accelerate the early-stage hydration and make the pastes more compact, leading to significantly less loss of compressive strength. Thus, adding some mineral admixtures into MKPC paste prepared with seawater could lessen the negative effect of seawater for mixing on the properties of hardened body. This study might provide useful information for application of seawater in mixing MKPC for marine construction.

Esmaeilnezhad E., Choi H.J., Schaffie M., Gholizadeh M., Ranjbar M.

Water can be magnetized under an applied magnetic field, and some important properties of magnetized water have become useful in industries associated with its surface tension, pH, viscosity, electrical conductivity, and scale formation inhibition. The surface tension of water decreases upon the application of a magnetic field, while its pH increases. In addition, the shear viscosity of magnetized water increases and the magnetic field inhibits scale formation. This paper reviews the unique properties of magnetized water as well as its potential applications as a smart and more environmentally friendly fluid in the oil industry, e.g., as an injection fluid in enhanced oil recovery areas for producing oil.

Ahmed H.I.

This research is the first attempt to determine the possibility of using magnetized water (MW) to improve fresh, mechanical, and microstructure characteristics of concrete incorporated with Egyptian nano alumina (NA). For this purpose, slump, compressive strength, desorption, and scanning electron microscopy (SEM) approaches were conducted. Eight concrete mixes and eight cement paste mixes were made with different NA contents (0, 1, 2, and 3% by weight of OPC). Two types of water, normal tap water (TW) and MW of 1.2 Tesla were used. Using MW instead of TW had led to a significant improvement in all considered characteristics of concrete. For non-magnetic concrete (NMC), the use of 1% replacement level of NA improved the properties of concrete. While, for magnetic concrete (MC), there was notable improvements in concrete characteristics of 1% NA and 2% NA specimens compared to control specimen. The proper content of NA to be used in both NMC and MC was 1% by weight of OPC. NMC made with 1% NA showed the highest increase in strength (17%) and decrease in capillary porosity (30%). MC made with 1% NA showed the highest increase in strength in (13%) and decrease in capillary porosity (27%) as compared to control specimen.

Wei H., Wang Y., Luo J.

This research investigates the shrinkage cracking of concrete, which were mixed with magnetic water. Magnetic water was obtained by the independent designed magnetizing equipment. Ring-test method and flat-test method were used to test early-age shrinkage cracking of concrete. Results show that the strain rate factor (α) and the total cracking area of unit area (c) of concrete were decreased when used magnetic water, which means the early-age shrinkage cracking resistance of concrete mixed with magnetic water is improved than those mixed with tap water. The best increase in early-age shrinkage cracking resistance of concrete is achieved when the magnetic strength is 260 mT and the length of magnetic field is 280 mm. Additionally, the compressive and split strength of concrete mixed with magnetic water increased greatly. It is also found that the length of magnetic field have direct effect on the growth of concrete strength.

Rashad A.M., Sadek D.M.

Ground granulated blast-furnace slag (designated as GGBS) has been utilized as building material due to the environmental, economic and technical benefits. In this study, the possibility of improving compressive strength of high-volume GGBS (HVS) paste before and after being exposed to elevated temperatures using metakaolin (MK) in micro-size (mMK) has been investigated. Portland cement (PC) has been partially substituted with GGBS at level of 70%, by weight, to produce HVS paste. Afterword, GGBS was partially substituted with mMK at levels ranging from 2% to 10% with an increment of 2%, by weight. After curing, the specimens were subjected to elevated temperatures ranging from 400 °C to 1000 °C with an interval of 200 °C for 2 h. Weight and compressive strength before and after being exposed to elevated temperatures have been thoroughly explored. The various decomposition phases formed were identified using X-ray diffraction (XRD) and thermogravimetric (TGA) analyses. The morphology of the formed hydrates was studied using scanning electron microscopy (SEM). The results showed that the compressive strength before and after being exposed to elevated temperatures increased with increasing mMK content. For all mixtures, the residual compressive strength at 400 °C reached its maximum peak value.

Abu-Taweel G.M.

Zamzam water is well documented for plenty of medicinal value for curing illness. In the present study, the effects of perinatal consumption of Zamzam and normal drinking water by the pregnant mice on their offspring's physical parameters, early sensory motor reflexes, locomotor activities, acetylcholinesterase (AChE) activity in the homogenize brain tissue and blood parameters were compared. To achieve that; Zamzam water was given to female Swiss-Webster strain mice as the only source of drinking fluid and the control animals were administered plain tap water. Treatment started from the first day of pregnancy and continued until the postnatal day fifteen of delivery. All offspring were subjected to various tests. The rate of body weight gain remained relatively unaffected until the second week of weaning period, however; in the last week the offspring exposed to Zamzam water gained significant body weight as compared to their control offspring. Furthermore, the opening of eyes and appearance of body hairs in Zamzam exposed pups remained unaffected as compared to the controls. The sensory motor reflexes in Zamzam exposed pups after birth and during the first two weeks of weaning period were significantly increased. Locomotor Activity Test performed in the male and female offspring after weaning period showed a significant decrease in the male and increase in the female on most of the elements of this test due to Zamzam exposure. AChE activity in the homogenized brain tissue and blood parameters were unaffected as compared to the controls, the present Zamzam effects in the offspring are possibly via in utero action and/or via mother's milk.

Çomak B.

Li Q., Geng H., Huang Y., Shui Z.

Chloride resistance of concrete with seawater mixing and metakaolin (MK) addition was evaluated by analytical techniques. With the combination of seawater mixing and NaCl solution curing, the compressive strength of concrete increased with MK content, which prevented the decrease of strength at 56 days. Both MK and seawater improved the chloride resistance which increased with MK content. The chloride ingress distance was reduced through the refinement of pore structure and immobilization of chloride by formation of Friedel’s salt. The minerals after chloride attack were characterized. The microstructure analysis along ingress direction confirmed the improvement of chloride resistance by MK and seawater.

Li Q., Geng H., Shui Z., Huang Y.

The effect of metakaolin (MK) and seawater mixing on the properties and hydration products of concrete was studied by analytical techniques. MK improved compressive strength by refining pore structure without altering porosity. Seawater increased compressive strength at early age without altering pore structure. The combination of MK and seawater improved both early and later age strength. Hydration products in pastes containing MK were Portlandite, ettringite, hemicarboaluminate, monocarboaluminate and C-S-H gels. In pastes with seawater, instead of hemicarboaluminate and monocarboaluminate, hydrocalumite was identified. MK promoted hydrocalumite formation. MK decreased CH content with increase of MK content and age. Seawater increased CH content at early age with MK content. The combination increased CH content at early age and decreased later. At 28 days, most chloride in seawater was immobilized by hydrocalumite. The combination improved properties of concrete at both early and later age.

Shi Z., Shui Z., Li Q., Geng H.

The effect of 0–6 wt% MK and mixing with seawater on the properties, hydration and microstructure of concrete was studied. The compressive strength at 28 days increased by 33% when addition of 5 wt% MK and by 22% when mixed with seawater. The combination of both increased compressive strength by 52%. The pore structure was refined under both conditions. There is a relationship between average pore diameter and compressive strength. MK promoted the formation of Friedel’s salt in concrete mixed with seawater. MK and mixing with seawater improved chloride resistance. This study shows that MK and seawater improved the performance of concrete.

Chen Q., Qu Z., Yin L., Liu J.

Rashad A.M., Mokhtar M.M., El-Nashar M.H., Abu-Elwafa Mohamed R.

Liu W., Zhao J., Feng Y., Zhang B., Xie J.

Seawater-mixed alkali-activated materials (Sw-AAMs) as a substitute to ordinary Portland cement (OPC) can reduce CO₂ emissions and alleviate water scarcity in areas with freshwater shortages. However, compared with freshwater-mixed alkali-activated materials (Fw-AAMs), introducing seawater with complex components can affect its reaction processes, fresh performance, mechanical properties, and durability. Therefore, the main characteristics of Sw-AAMs and their comparison with Fw-AAMs are reviewed in this study. The results show that seawater directly affects the reaction process of Sw-AAMs, leading to the formation of by-products such as M–S–H gel, Cl-hydrotalcite, and gypsum, which are not observed in Fw-AAMs. The type of activator anion (particularly SiO₃2⁻) is a key factor affecting various properties. In a system without SiO₃2⁻ ions, the addition of seawater increases the initial fluidity of the paste, reduces its setting time and increases the early strength of Sw-AAMs by 11–30%. However, when SiO₃2⁻ ions are present in the activator, the reduced formation of early primary products, coupled with the insufficient cross-linking ability of the by-products, decreases the early compressive strength of Sw-AAMs by up to 30%. Although seawater may affect the homogeneity of the cementitious material, there is a good interaction between the seawater-mixed matrix and aggregates, which helps enhance the elastic modulus and flexural toughness of Sw-AAM concrete. The research on long-term durability of Sw-AAMs and modelling of concrete at different scales is still in its infancy. Further research is required to ascertain the long-term behaviour of Sw-AAMs and to facilitate broader and more accurate applications.

Huang Z., Zhou Y., Xiang S., Sui L., Guo M.

Cai R., Liu Q.

Rashad A.M., Mosleh Y.A., Mossalam E.A., Gharieb M.

Kamali S., Ponomar V., Dal Poggetto G., Leonelli C., Kilpimaa K., Luukkonen T.

Water-intensive industries face challenges due to water scarcity and pollution. In the management of these challenges, membrane processes play an important role. However, they produce significant amounts of reject waters, in which the separated salts and pollutants are concentrated. This study aims to develop a novel management concept for reject waters using alkali activation to immobilize salts in a solid phase using metakaolin, blast furnace slag (BFS), or their mixture as precursors and to create alkali-activated materials with sufficient properties to be potentially used in construction applications. Seven different waters were used to prepare the NaOH-based alkali activator solution: deionized water, three simulated seawaters with increasing salinity, and three reverse osmosis (RO) reject waters from mining or pulp and paper industries. Overall, BFS-based samples had the highest immobilization efficiency, likely due to the formation of layered double hydroxide phases (hydrotalcite, with anion exchange capacity) and hydrocalumite (chloride-containing mineral). Moreover, high-salinity water enhanced the dissolution of precursors, prolonged the setting time, and increased the compressive strength compared with nonsaline water. Thus, the obtained materials could be used in construction applications, such as backfilling material at mines where RO concentrates are commonly produced.

Demir I., Alakara E.H., Sevim O., Kartal S.

This study investigates the impact of magnetized water (MW) on the fresh and hardened properties of alkali-activated slag (AAS) mortars incorporating raw marble powder (RMP) and calcined marble powder (CMP). In the initial stage of the study, control specimens were manufactured to ascertain the optimal parameters for molarity, curing temperature, and curing time. The optimal parameters were determined based on the highest strength results: a molarity of 10, curing time of 24 hours, and curing temperature of 110 ℃. In the second stage of the study, while maintaining these optimal parameters, RMP and CMP were substituted in place of blast furnace slag (BFS) at rates of 10%, 20%, 30%, and 40%. In this study stage, tap water (TW) and MW were employed as the mixing water. A mini-slump test was conducted to assess the fresh state properties of the prepared AAS mortars. Subsequently, ultrasonic pulse velocity (Upv), flexural strength (ff), and compressive strength (fc) tests were carried out to evaluate the hardened state properties of the specimens. Finally, scanning electron microscopy (SEM) analysis was performed to examine microstructural properties. According to the results, the ff and fc values of the mortars produced with CMP substitution using TW showed an increase of up to 20.6% compared to the mortars based on RMP and produced withTW. Additionally, utilizing MW as the mixing water enhanced the workability of AAS mortars. Consequently, incorporating CMP and MW in AAS mortars further improved fresh and hardened state properties compared to RMP and TW.

Zhang S.S., Wang S., Chen X.

Seawater-based geopolymers potentially capitalize on the abundant seawater and reduce the CO2 emissions for marine/offshore constructions. Unlike the well-documented seawater ions (e.g., Ca2+, Na+, and Cl−), existing studies on magnesium-ion (Mg2+)-induced changes of geopolymers, especially the non‑calcium mixtures, have been limited. In this study, Mg2+ was confirmed to retard the setting of sodium-silicate activated metakaolin from Vicat and calorimetry tests. Through chemical extraction and spectroscopy characterization, the retardation mechanism was found mainly due to the consumption of OH− via Mg2+ in the activating solution, which decelerated the dissolution and condensation during geopolymerization. Supplemental Vicat penetration under a controlled alkalinity indicated a further retardation via the "coating effect" of magnesium silicate hydrate (M-S-H) gels, which were produced by the interaction of Mg2+ and the aqueous silicates. These findings substantiate the tailorability of setting by Mg2+, an abundant marine resource, thereby paving the way to develop eco-friendly cementitious binders with balanced performance.

Aruntaş H.Y., Korkmaz Y., Demir İ., Kaplan G.

Fly ash (FA), which is utilized to create the next generation of green concrete for contemporary buildings, is widely accessible throughout the world. This study investigated the activation of concretes with 0, 5, 10, 15 and 20% Class C fly ash (CFA) by seawater. Seawater was used for curing and mixing water to determine the effectiveness of the activation process. Fresh state, compressive strength, carbon footprint and cost properties of CFA and non-CFA concrete were analyzed. Fresh state, compressive strength, carbon footprint and cost properties of CFA and without CFA concrete were analyzed. The slump values of the concrete were adjusted according to the S3 class specified in the EN 206 standard. The densities of the fresh concretes ranged between 2366 and 2417 kg/m3, while the fresh densities decreased slightly as the CFA content increased. The 28-day compressive strength of the concretes varied between 17.9 and 39.1, and the 90-day compressive strength ranged between 22.2 and 40.4 MPa. Generally, using up to 10% CFA can increase compressive strength. Using seawater as mixing water rather than curing water increases the compressive strength. The CO2 emissions and costs of concretes decrease as the CFA content increases. Concrete using 20% CFA can reduce CO2 emissions by up to 19% and costs by up to 6% compared to the reference. As a result, the carbon and cost performances of the concrete improve more when seawater is used in the mix water, and CFA is used at a ratio of 10%. In addition, seawater is more suitable for the activation process of CFA-containing concretes.

Rashad A.M., Abdu M.F., Ezzat M.

Egypt is a rich country with natural volcanic glass, which can be utilized to produce possibility volcanic glass powder (VGP). This VGP can then be employed as a pozzolanic material for the Portland cement (PC) system. In this investigation, for the first time, the possibility to employ Egyptian volcanic glass powder (VGP) as a modifier agent for alkali-activated slag (AAS) cement was studied. The volcanic glass (VG) was delivered from a quarry in the form of lumps pieces. After crushing and powdering, it was blended with slag in proportions of up to 30 wt% of slag (as a partial replacement). The slag free from VGP and those containing VGP were activated by an alkaline activator to produce alkali-activated cement. The effect of various ratios of VGP on flowability, setting time, compressive strength, transport properties, environmental conditions measured by wetting/drying cycles, crystalline phases, hydration products, and microstructures of AAS cement were investigated. The results confirmed that VGP is an amorphous material rich in silica and has a suitable ratio of alumina. The incorporation of 10% VGP was the optimal ratio. Higher ratios of VGP than 10% showed an adverse effect on the AAS cement properties.

Khattab S.A., Elshikh M.M., Elemam W.E., Elshami A.A., Youssf O.

One of the most important challenges in developing the concrete industry is to use sustainable materials that are able to improve concrete properties. Magnetized water (MW) is a type of water that can replace tap water (TW) in conventional concrete and enhance its mechanical properties. However, the performance of MW in geopolymer concrete has not been well investigated up to now. The goal of this study is to measure the effect of using an alkaline activator (AA) made of MW on the mechanical properties and durability of fly ash (FA)-based geopolymer concrete. The AA was a mixture of sodium hydroxide (SH) solution and sodium silicate (SS) solution. Eighteen geopolymer concrete mixes were tested for several fresh, hardened, and durability properties. Of these mixes, nine were prepared with AA made of MW and the other nine were the same but prepared with AA made of TW. The preparation of MW was simply carried out by passing TW across permanent magnets of 1.6 Tesla, and then 1.4 Tesla intensities for 150 cycles. The MW-based AA properties were analyzed and compared to those of the conventional TW-based AA. Several mechanical and durability properties were measured. Scanning electronic microscopy (SEM) analysis was also conducted on selected mixes. The outcomes of the hardened concrete tests demonstrated that while using MW to prepare AA solution contained SH with a molarity of 16 M, an SS/SH ratio of 2, an AA/C ratio of 0.4, a W/C ratio of 10%, and a curing temperature of 115 °C could display the best outcomes in this study when used in geopolymer concrete. Using MW in a geopolymer concrete AA could increase its slump by up to 100% compared to that made of TW. Using MW in the AA enhanced the compressive strength by up to 193%, 192%, and 124% after 7, 28, and 56 days, respectively. The SEM analysis showed that using MW clearly enhanced the surface morphology of geopolymer concrete. The proposed geopolymer concrete made using the MW-based AA in this study sheds the light on a new class of eco-friendly concrete that could possibly be used in many structural applications.

Sun Z., Li X., Liu Q., Tang Q., Lin X., Fan X., Huang X., Gan M., Chen X., Ji Z.

The development of sustainable cementitious materials is essential and urgent for the construction industry. Benefiting from excellent engineering properties and a reduced greenhouse gas footprint, alkali-activated materials (AAM) are among the robust alternatives to Portland cement for civil infrastructure. Meanwhile, concrete production also accounts for around 20% of all industrial water consumption, and the global freshwater shortage is increasing. This review discusses recent investigations on seawater-mixed AAMs, including the effects of seawater on workability, reaction mechanism, shrinkage, short and long-term strength, binding of chloride and corrosion of steel reinforcement. Attention is also paid to the utilization of sea sand as aggregate, as well as discussions on the challenges and further research perspectives on the field application of AAMs with seawater and sea sand.

Sevim O., Alakara E.H., Demir I., Bayer I.R.

This study investigates the effect of magnetic water (MW) on the properties of slag-based geopolymer composites (SGCs) incorporating ceramic tile waste (CTW) from construction and demolition waste (CDW). The presented study consists of two stages. In the first stage, reference mortars without additives were produced, and optimum parameters for molarity, curing temperature and curing time were determined. Tap water (TW) was used as mixing water, and blast furnace slag (BFS) was used as a precursor in SGCs in this stage. SGCs were produced using different alkali activator concentrations (12, 14 and 16 M) and were cured for either 24 or 48 h in an oven at ranging from 60 to 110 °C. Ultrasonic pulse velocity (Upv), flexural strength (ffs), and compressive strength (fcs) tests were performed on the produced SGCs. The results of these tests indicated that optimum paramaters for molarity, curing temperature and curing time parameters were determined to be 16 M, 100 ℃ and 24 h, respectively. Then, TW and MW were used as mixing water, and BFS and CTW were used as precursors in the second stage. At this stage, SGCs were produced using 16 M and cured in an oven at 100 ℃ for 24 h. In the mixtures, CTW was used by substituting 10, 20, 30 and 40% by weight of BFS. In the second stage, workability, Upv, ffs, and fcs tests as well as microstructure analyses, were performed on the produced SGCs. Microstructure analyses were performed with scanning electron microscopy (SEM). According to the results, Upv, ffs, and fcs increased compared to the reference SGCs when 10% of CTW was used. Additionally, when MW was used as mixing water, there were increases in workability, Upv, ffs, and fcs results compared to those produced with TW. From SEM analyses, it has been observed that MW accelerates the polymerization process of SGCs containing CTW and reduces the pore size of SGCs. As a result, it has been determined that MW can improve the fresh and hardened state properties and microstructures of SGCs containing CTW.

Elshami A.A.

Abstract This paper presents the experimental approach and the first results obtained as a result of the effect of five Sources of mixing water on produce more durable concrete. Five types of water were used, namely simulated acid rain (AR), Rain water (RW), tap water (TW), Zamzam water (ZW) and sea water (SW) as mixing water for ordinary portland cement concrete OPCC. The durability of these different types of water were tested toward their capacity to prevent the rebar corrosion. The results of workability, pH value, compressive strength, chlorides penetration and microstructure of different specimens mixed with each type of water were compared with those mixed with tap water (TW).