جستجوی مقالات مرتبط با کلیدواژه « آب مغناطیسی » در نشریات گروه « عمران »

The present study aimed to investigate the experimental performance of the effect of magnetic water on the mechanical properties of concrete containing basalt fibers. In this study, AQUA-Correct (AC) device made in Germany, which has a power of about 1300 Gauss, has been used to produce magnetic water. Concrete samples prepared (24 samples 7 and 28 days for compressive strength test and 24 samples 7 and 28 days for flexural strength test) are made by this machine with one and two times passing through the magnetic field. The fibers used are basalt fibers that it has a length of 3 cm and a diameter of more than 9-10 microns. It has high heat resistance and sound absorption and has effective applications in the manufacture and reinforcement of composite materials and is 0, 2 and 5% by weight of cement in the mixing plan. Basalt fibers have been studied on the properties of concrete such as compressive strength, flexural strength, slump and specific weight. The results showed that by increasing water magnetism, slump, specific weight and compressive strength and the flexural strength of concrete increases, also by increasing basalt fibers, slump and specific weight decreases and by increasing the percentage of fibers from 0 to 2, the compressive strength increases and from 2 to 5%, we face a decrease in compressive strength, resulting in that 2% is an optimal percentage of basalt fiber. However, by increasing percentage of fibers, flexural strength has been increased significantly.

In this study, to evaluate the effect of magnetic water along with the effect of smelting slag on concrete, electrical resistance tests, water permeation depth and frost and melting resistance tests were carried out. Three types of environmental conditions (sulfate, chlorate and ordinary water solutions) and conventional water ponds were used to perform the tests. The mixing design used in this study has two types of compressive strengths of 25, 40 MPa. The results showed that magnetic water has a great effect on the concrete and its application increases the specific electrical resistance of the concrete and reduces the chance of corrosion of buried steel in the concrete. Magnetic water also reduces the depth of water infiltration, increases the number of thawing and frost cycles, and increases the durability index. Increasing the percentage of smelting slag in concrete increases the specific electrical resistance of concrete, decreasing water penetration depth, increasing the number of frost and melting cycles, and concrete durability index. Increasing the compressive strength of the concrete from 25 to 40 MPa in addition to having a great effect on the mechanical properties, increased the specific electrical resistance of the concrete, decreased the water penetration depth, and also increased the number of frost and thaw cycles and the concrete durability index. It should be noted that the samples exposed to the sulfate medium performed better than the samples exposed to the chlorate medium and had lower electrical resistance and increased water penetration depth than the samples exposed to ordinary water.

Magnetic water changes the electron configuration of the ions, followed by significant changes in hardness, electrical conductivity of surface tension and other physical and chemical properties of water. These changes in the cement reaction create a situation that has a significant impact on the improvement of the properties of concrete in fresh and hardened states and is therefore of concern to the researchers. One of the basic characteristics of magnetic water, which is very important in the production of concrete, is the dependence of water on particles and colloidal solutions. When water is mixed with cement, a colloidal solution of cement is obtained, which if the water magnetic is used, the particles of the cement are surrounded by a single molecular layer of water with a lower density. This phenomenon makes it possible to reduce the amount of water used in the mixing of concrete, which will have a lot of benefits in concrete. Magnetization of water increases the hydration of negative ions, which damages the crystalline structure of the water. This paper studies the researches on magnetic water and its effect on the mechanical properties of lightweight concrete has been analyzed. The most influence of magnetic water on the mechanical properties of lightweight concrete has been obtained at the intensity of the magnetic field of 1 Tesla. The highest workability of cement paste made with magnetic water was obtained by rotation of 65 minutes of water in a magnetic field with intensity of 1 Tesla. The most effective magnetic field intensity is achieved in 1 Tesla for magnetic field.

AbstractIn this study, the toughness and durability of concrete with recycled aggregates and magnetic water against melting and freezing cycles and mechanical properties such as compressive and tensile strengths are investigated. Variables include the number of different cycles of water in the magnetic field, different amounts of super-plasticizer, steel fibers and micro-silica. A total of 242 samples were made in 11 different mix designs. It should be noted that half of the samples mentioned contains steel fibers. The results of most experiments have shown that magnetic water, although having a very high effect on the mechanical properties of concrete, should not be used alone as a compensating agent for defects caused by recycled aggregates. Using microsilica as a mineral admixture with magnetic water improves the concrete properties, significantly. The toughness indices were determined by ASTM C1018, JSCE and PCS method and concrete durability test by BS EN 140: 2003. Among the recycled aggregate concrete mixes, the best toughness results were for the samples containing microsilica and steel fibers. Also, ten round magnetic water resulted in an increase in the durability of recycled aggregate concrete by approximately 25% compared to one round of magnetization.

The present study investigates the punching shear behavior of flat slabs strengthened by ECC concrete. In addition, it studies the effect of magnetic water in a mixture of ECC concrete. In the experimental part of the study, nine reinforced concrete slab specimens with the dimensions of 1000times1000 mm with the same reinforcement ratio were constructed and tested. The reinforcement ratio of the slabs was . The slab thickness varied in different specimens. One specimen with mm thickness was made of plane concrete. Six specimens were made by combining the plane concrete and ECC concrete layers with different thicknesses of and mm. Two of the specimens were made by ECC concrete with mm thickness. The mixture of plane concrete incorporated an ordinary Portland cement with a water-cement matrix ratio of . This ratio was for ECC Concrete. In some specimens, the U-shaped shear studs were used for a better connection between the ECC concrete and plane concrete layers. ECC concrete has been used on the tension side of the slabs. Both punching shear strength and displacement of each specimen were measured by a Linear Variable Displacement Transducer (LVDT). During the punching shear tests, the load and maximum deflection were recorded by a data acquisition system and ‌onsequently, the load-displacement curves were drawn. The tests were conducted using a testing machine to apply the load at an average rate of kg/sec. A hydraulic jack was fixed to the frame and used to apply the concentric load on the column stub. The hydraulic jack had a maximum capacity of kN. The results of the tests indicated that the ECC concrete enhanced the punching shear strength of slabs. The magnetic water improved the ECC concrete flow and load-carrying capacity of the slabs. U-shaped shear studs increased the load-carrying capacity of the specimens.

The main objective of this study was to assess engineering properties of self-compacting concrete (SCC) incorporating magnetic water and various percentages of natural zeolite. The fresh properties of SCC were investigated by means of slump flow, T50, V-funnel, L-box and visual stability index (VSI). At hardened state, mechanical properties and durability characteristics of concrete were evaluated by means of compressive and tensile strength tests, modulus of elasticity test and water absorption test at different ages under both wet and dry curing conditions. The results of fresh concrete indicated that magnetic water and natural zeolite in SCC can improve the rheological properties and stability of SCC where the magnetic water is able to increase the slump flow up to 3% and decrease plastic viscosity of concrete mixture up to 6% without aggregates segregation. In addition, the presence of magnetic water and natural zeolite improves mechanical properties and durability of SCC. According to this, compressive and tensile strengths and modulus of elasticity of SCC containing magnetic water and 20% natural zeolite were increased up to 42, 12 and 33 %, respectively, at the age of 90 days. In the same concrete mixture, the value of water absorption was decreased up to 48%.

The use of concrete in construction projects is increasing day by day. Making concrete with different properties, compatible with the conditions of each project, is necessary and unavoidable. So far, researchers have conducted research on the characteristics of this type of concrete. However, the role of water consumption in the mixing and curing of this type of concrete has not been studied much. Also, in some countries, studies are being conducted on the use of magnetic water and its effect on concrete. The purpose of this article is to investigate the changes in the properties of self-compacting mortars in the fresh state, due to the use of magnetic water in the construction phase, and therefore small slump tests and small v-shaped funnels are used as important criteria using normal and processed waters. It has been done for 5, 10, 15 and 20 minutes. The results of the tests show that magnetic water improves the rheological properties of fresh mortar.

Today, concrete plays important role in civil engineering and construction industry. From the past until now, increasing compressive strength, durability and workability have been among the most important components considered by concrete technology researchers. Due to the fact that water is one of the most important components of concrete mixes and forms a volume of 15 to 25% of concrete, its quality plays a key role in concrete. One way to increase workability and strength in countries such as China and Russia is to use magnetic technology in concrete construction. In this way, using magnetic technology, magnetic water is produced and used in mixing concrete. In the present paper, an attempt is made to review the studies and experiments performed in connection with the use of magnetic water in concrete mixes.

Self-compacting concrete is one of the most important and significant achievements of concrete technology. In some countries, studies are being conducted on the use of magnetic water and its effect on concrete. According to the results of this research, by applying a magnetic field to ordinary water, the structure of its molecules changes so that it can be said that as water molecules pass through a magnetic field, there is a significant change in the arrangement of them in the liquid. In this paper, changes in the properties of hardened self-compacting mortars due to the use of magnetic water in the fabrication and processing stage have been investigated. It has been done for 5, 10, 15 and 20 minutes using ordinary water as well as processed water. The results of the experiments show that magnetic water improves the strength standards of hardened concrete. Therefore, in order to achieve a certain level of efficiency and strength, if the magnetic water is used, the ratio of water to concrete or superplasticizer can be reduced.

self-compacted concrete(SCC) is a concrete that can flow in the space between reinforcement without separation and compact only by their own weight. In this study, the effect of using silica fume, metakaolin, rice husk ash and fly ash with different ratios of 10% and 20% by weight of cement in self-compacting concrete containing magnetic water is concered. The fresh properties of self compacted concrete were's tested by means of slump flow, T50, V-funnel, L-box and visual stability index(VSI). The hardened properties were assessed, using compressive strength at the ages of 7 and 28 days. Also splitting tensile strength and water absorption test were assessed at the age of 28 days. In addition, concrete specimens were made using tap water and magnetic water, was passed through a magnetic field of 0.8 Tesla. The results show that pozzolanic materials are suitable in properties of self-compacting concrete containing magnetic water in terms of flowability and viscosity. Moreover, magnetic water can reduce the amount of superplasticizer, required for SCC, up to 45%. Also the results of hardened SSC show an improvement in mechanical and durability properties of concrete. The usage of silica fume with ratio 20% by weight of cement in self-compacting concrete containing magnetic water, increases the compressive and splitting tensile strengths by 48% and 35% respectively and decreases amount of water absorption by 55% at the age of 28 days.

Nowadays, concrete is one of the most important and widely used human product. Improving concrete characteristics have always been one of the fundamental subjects for engineers. Improve the physical properties of water, as one of the main elements of concrete, is one way to improve the characteristics of the concrete. When water passes through the magnetic field, its physical quality has changed, it is called Magnetic water. This study examines the effect of the use of magnetized water (MW) with a solenoid current-carrying, on the compressive strength and workability of high performance concrete. The variables of this study were the intensity of magnetic field, the silica fume replacement level and water to cement ratio in different mixes. The results show that using MW increases the workability of concrete about 36% in average.MW in combination with superplasticizer is more effective than MW on workability and compressive strength of concrete. MW had more positive effects on the samples without silica fume. Increasing the intensity of magnetic field improved the workability, 28 and 90 days compressive strength concrete.

When subjected to a magnetic field, the hydrogen bonds between water molecules become weakened, and the water molecule clusters break down into smaller ones. This allows for the water to more easily penetrate into cement particles, causing a faster and more effective hydration process. In order to assess the effect of magnetic water on curing and workability of cement past and wet concrete, also the compressive strength of condensed cement as well as concrete, first, a magnetic treatment device was designed and built in this study. The magnetic water produced was mixed with cement to make cement pastes with different water-to-cement (w/c) ratios. Curing time, workability, and compressive strength of such cement pastes were investigated. Then, using well balanced aggregates, magnetic water, cement with different proportions, and micro-silica, concrete with different mix designs were made and tested. Among the results from this study are: 1) The optimized magnetic field intensity for producing magnetic water is 0.8 to 1.0 tesla. 2) Magnetic water reduces the primary and secondary curing of cement by 50% and 19%, respectively. 3) The best compressive strengths are obtained if the water is circulated through the magnetic field for about 15 minutes, and the best workability is obtained if this time is about 65 minutes. 4) For higher proportions of cement in mix design and the application of magnetic water, the resulted concrete compressive strength may be increased by 20% and even higher. 5) In addition to enhancing the level of cement hydration, application of magnetic water takes more advantage of micro-silica in improving concrete strength. For example, the simultaneous application of micro-silica and magnetic water increases the 7-day-strength by 46% and the 28-day-strength by 39%. It is noteworthy that if one were to choose either application of micro-silica or the magnetic water for enhancing the concrete compressive strength, results here show that the application of micro-silica is slightly more effective. In general, the application of magnetic water increases the speed of concrete strengthening and/or the hydration process. In fact the rate of this strengthening for the 7-day-concrete is much more than that for the 28-day-concrete.