میکروسیلیس

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Vahid Shapouri Mohammad Reza Alavi Moghadam Taghi Ebadi

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Open Access Article

2 - The Effect of PVA Fibers and Nano-Particles on the Bonding Strength of Fiber Reinforced Concrete
hossein nematian jelodar Ata Hojatkashani Rahmat Madandoust Abbas Akbarpour Seyed Azim Hosseini

Abstract Repairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond More

Abstract Repairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond strength parameter of materials is one of the important properties in the selection of repair mortars. In the current Experimental studies, the bond strength of 7 types of cement base mortars consisting Nano-Silica (NS), Micro-Silica (SF) and Polyvinyl Alcohol (PVA) fibers have been tested on base concrete according to ASTM C882 standard. The base concrete is made of fiber concrete with a target compressive strength of 45 MPa and consisting macrosynthetic fibers. The workability of fiber concrete was 120 mm, and the method of curing the samples was done as the wet method. The obtained results indicate that all 7 types of repair materials of this research were compatible with the base concrete and the sample with the combination of PVA fibers and Nano-Silica in cement-based mortars has increased the bond strength of the samples by 85% compared to the samples without fibers. The highest bond strength among the samples was related to cement based mortar containing PVA fibers and Nano-silica (PVA0.75NS6) with bond strength equal to 21.83 MPa. Manuscript profile

Open Access Article

3 - Investigating the Effects of Using Microsilica and Nanosilica on the Hardened Mechanical Properties and Durability of SCC Containing Recycled Aggregates
Reza Farokhzad mohsen mehrpoya

     Today, the wastes remaining from concrete degradation is considered as an environmental problem and is one of the biggest challenges in the building industry. Accordingly, many researchers have decided to re-use the materials of aggregates from More

     Today, the wastes remaining from concrete degradation is considered as an environmental problem and is one of the biggest challenges in the building industry. Accordingly, many researchers have decided to re-use the materials of aggregates from degradation in concrete production cycles. In this paper, attempts were made to assess and if possible to promote the mechanical and durability characteristics after the addition of nano-silica and micro-silica to self-compacting concrete containing recycled aggregates (obtained from worn concrete degradation). One of the points to be considered in this paper was the attempt to use tests such as half-pole testing and concrete wave velocity. In this regard, 72 mixture designs were studied in 8 collections. In these mixture designs, with respect to the content of recycled aggregates, the nano- and micro-contents were changed. Then, the samples underwent mechanical tests including compressive strength and tensile strength, and durability tests including corrosion potential, concrete wave velocity (ultrasonic) and electrical strength. After the tests, with an increase in the use of nano-silica and micro-silica, the efficiency and fluidity of the fresh concrete were reduced, and compressive strength and tensile strength were increased. Also, at fixed strength, nano-silica caused less efficiency and fluidity than micro-silica and also, with an increase in the content of recycled aggregates in concrete, efficiency and fluidity as well as compressive strength and tensile strength of concrete were reduced. Manuscript profile

Open Access Article

4 - Experimental investigation on Quartz Powder effect on Compressive Strengths of High Strength Concrete (HSC)
javad javadi Masoud Pourbaba

HSC has great mechanical properties and durability and is one of technology developments in concrete. This type of concrete has high cohesion, compressive strength and low water to cement ratio and permeability which results to high durability. HSC is a cemental composi More

HSC has great mechanical properties and durability and is one of technology developments in concrete. This type of concrete has high cohesion, compressive strength and low water to cement ratio and permeability which results to high durability. HSC is a cemental composite product that contains optimum amount of fines and with a water to cement ratio (W/C) less than 0.25.High performance concrete compared with normal concrete has a structure with discontinous pores that results to high performance and minimum water permeation to concrete. HSC’s admixture contains water, silica fume, cement, fine sand, super plastisizer and rock powder like quartz that in this study are used of Iran’s local materials. In this study 10x10x10 cube specimens were made and evaluated. Compressive leads to failure were applied to concrete specimens. The purpose of this study is investigation of quartz powders increase in HSC.Results shows that concrete compressive strength with 11% quartz powder is the highest and increase in quartz powder lead to brittle pre failure and explossive failure of concrete specimens.Other considerations shows that increase of quartz powder leads to more crack on concrete and it is suggested to use fibers to prevent more crack in this type of concretes. Manuscript profile

Open Access Article

5 - An Experimental Study of the Effects of Silica Fume Products on Properties of Hardened Concrete
Ahmad maleki fardin esmaeili

Today, concrete is known as one of the most used building materials in the world. Silica fume and its products are now known as one of the best mineral additives in concrete. Silica fume is mainly used to improve the properties of hardened concrete so when using Silica More

Today, concrete is known as one of the most used building materials in the world. Silica fume and its products are now known as one of the best mineral additives in concrete. Silica fume is mainly used to improve the properties of hardened concrete so when using Silica fume concrete properties after hardening usually more significant. But although various experiments have been conducted on the subject. But this thesis is considering other products of silica impact on the hardened concrete properties have been investigated, including compressive strength, permeability and Thawing -freezing of hardened concrete. Three mixing ratio is tested in the laboratory: 1- without additives and 350 kg per cubic meter of cement, 2- with 10% Silica fume powder and one percentage lubricant, 3- with 10% of the micro gel. Based on lab work conducted in the research and the gathering of results can be explained by the properties of hardened concrete, the use of powder and gel of Silica fume increased compressive strength of 37.5 and 56 percent respectively. Water penetration rate, in the second ratio increase 50 percent and in the third ratio decreased 25 percent, compared to the first ratio. The results indicate the desirability of Silica fume gel long-term impact on the quality of hardened concrete including its durability. While the silica fume powder, could adversely affect the permeability and Freezing-Thawing of concrete. Manuscript profile

Open Access Article

6 - Laboratory Evaluation of Dynamic Modulus of Elasticity Cement-Based Grout to Improve the Quality by Using Nano and Micro-Technology
meysam shirzad shahrivar Amin Gholizad

Measurements of the speed of passing ultrasonic waves are used to determine the quality and strength of materials. Velocity of ultrasonic waves of solids depends on the density and elasticity characteristics. The quality of material depends on the firmness and elasticit More

Measurements of the speed of passing ultrasonic waves are used to determine the quality and strength of materials. Velocity of ultrasonic waves of solids depends on the density and elasticity characteristics. The quality of material depends on the firmness and elasticity of the, so measurement of the speed of passing waves can be used to determine the  quality of and elastic properties. According to the application of cement based grout to bridge the gap between the members and the concrete foundation and the ability to absorb and transmit static and dynamic loads by grout into the foundation, structural engineers need to grout with high quality, strength and durability that has a strong internal structure and with minimal pores and cavities inside. Ultrasound waves passing speed test is done to check these features and its results are presented based on dynamic modulus of elasticity. The results show that the modified grout mix with nano-silica, silica fume, and dynamic modulus of elasticity increased so that by replacing 1% nano-silica powder and 20% micro silica powder in grout combination with cement, dynamic modulus of elasticity  increased  to 64%. Manuscript profile

Open Access Article

7 - Investigation of rheological and mechanical properties of two-component and three-component mortars containing microsilica and slag
Seyed Fathollah Sajedi wilbert karamian

With the use of pozzolans and additives, today, a huge change has been made in mortar technology to achieve high strength and durability. The purpose of this study is to make two-component and three- component mortars and compare their rheological and mechanical propert More

With the use of pozzolans and additives, today, a huge change has been made in mortar technology to achieve high strength and durability. The purpose of this study is to make two-component and three- component mortars and compare their rheological and mechanical properties. In this research, compressive, flexural and tensile strength tests were performed on reference mortar, two-component mortars as well as three-component mortars. Slag utilized in making of research mortars was produced in Ahvaz Steel plant. Compressive strength tests were conducted at 7, 28, 56 and 91 days and flexural and tensile strength tests were performed at 28 and 91 days. In the mentioned resistance tests, cubic specimens with dimensions of 50 mm, prismatic specimens with dimensions of 160 × 40 × 40 mm and standard bow-tie specimens were applied, respectively. The results presented that the replacement of microsilica up to 10% by weight of cement increased the compressive, flexural and tensile strengths of two-component mortars, which were significant at all ages compared to the sample without microsilica. With increasing cement substitute microsilica up to 15%, changes in compressive, flexural and tensile strengths follow an inverse nonlinear behavior. Optimal microsilica and slag replacement percentages of 5% and 10%, respectively, increased the three strengths in the three-component mortars, which are significant at all ages compared to the reference sample. With increasing the percentage of replaced microsilica, the flowability of the mortars decreased and with increasing the percentage of slag, the flow increased. Manuscript profile

Open Access Article

8 - Comparison of the effect of silica fume and fly ash on the mechanical properties of masonry recycled concretes
Mostafa Azhdarizadeh Seyyed Fathollah Sajedi Mohammad Sirous Pakbaz

10.30495/civil.2023.701859

The present study is devoted to the study of the effect of replacing silica-fume (SF) and fly ash (FA) pozzolans on the mechanical properties of recycled concrete (RC) made from recycled masonry coarse aggregates (RMCA).  In manufactured concretes, natural aggregat More

The present study is devoted to the study of the effect of replacing silica-fume (SF) and fly ash (FA) pozzolans on the mechanical properties of recycled concrete (RC) made from recycled masonry coarse aggregates (RMCA).  In manufactured concretes, natural aggregates were replaced by RMCA at different percentages. In order to improve the mechanical properties of these concretes, different percentages of SF and FA were substituted for part of the cement. Slump and specific gravity tests were performed on fresh concrete and compressive strength, splitting tensile strength, modulus of elasticity, and ultrasonic pulse velocity tests were performed on the hardened concrete. The results indicate that replacement of SF and FA increased the slump and decreased the specific weight of the concretes. Also, the results revealed that replacing 5% and 10% SF improved some mechanical properties of recycled concrete containing 50% of RMCA. Replacement of 15% SF, in concrete containing 25% of RMCA resulted in the close mechanical properties of RC compared with CC without pozzolans. Also, the test results demonstrated that replacing different percentages of Fly Ash, could not improve the mechanical properties of RC. Manuscript profile

Open Access Article

9 - Effect of Air Entrain and Microsilis Additives on Light Weight Perlite Concrete
Mahin Ganadi mohammadali lotfolahiyagin Raheb Amiri

Abstract This paper presents the results of a laboratory study carried out on effect of using microsilis and air entrain on compressive strength of light weight perlite concrete. In this study, 63 test specimens with different percentage and mixtures including microsil More

Abstract This paper presents the results of a laboratory study carried out on effect of using microsilis and air entrain on compressive strength of light weight perlite concrete. In this study, 63 test specimens with different percentage and mixtures including microsilis and air entrain were used. 63 test specimens including microsilis were also prepared for comparison purposes. Laboratory test results showed that workability and compressive strength can be increased, and density can be decreased by the use of air entrain and microsilis. These results showed that concrete mixture incorporating 0.5% air entrain and 10% microsilis can be optimum case Manuscript profile

Open Access Article

10 - Effect of Water-Cement Ratio on Abrasive Strength, Porosity and Permeability of Silica Fume Concretes
Abolfaz Shamsayi Mohsen nacharchi Saber piroti Kamal rahmani

Abstract Today following the development of construction of hydraulic structures like dams, the matter of concrete durability used in these kinds of structures has gained paramount importance. One of the important factors of concrete durability in these structures is i More

Abstract Today following the development of construction of hydraulic structures like dams, the matter of concrete durability used in these kinds of structures has gained paramount importance. One of the important factors of concrete durability in these structures is its resistance against abrasion due to the crash of particles carried by water. To enhance the abrasion resistance of concrete, different methods have been offered and investigated by researchers and one can refer to the following to name a few. Using aggregates resistant to abrasion, reducing the water-cement ratio, using nanocilica microcylis in concrete, suitable and on time seasoning. In the present research the following experiments have been done on concrete samples. -The abrasive strength of block samples of 15×15×15 cm  for 28 past days using Sand Blast Method. -The hydraulic conductivity coefficient of cylinder samples with the height of 10cm., and 10cm., in diameter, 28 past days using Penetration Method. The results of abrasion experiments showed that by reducing water-cementratio from 0.50 to 0.33, the abrasive strength of concrete improves as far as 30.94 %. The permeability experiments showed that; By reduction of water-cement ratio from 0.50 to 0.33, the hydraulic conductivity coefficient of the concrete is reduced from 39.88 × 10 m/sec to 2.49 × 10 m/sec., and the porosity of concrete is reduced from 13.90 % to 13.10 %. The above results show that reducing water-cement ratio results in increasing abrasive strength and increasing the hydraulic conductivity coefficient and reducing porosity of silica fume concrete. Manuscript profile

Open Access Article

11 - The Effect of PVA Fibers and Nano-Particles on the Bonding Strength of Fiber Reinforced Concrete
hossein nematian jelodar Ata Hojatkashani Rahmat Madandoust abbas akbarpour nik ghalb rashti Seyed Azim Hosseini

Repairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond strength More

Repairing and Strengthening of concrete structures is of special importance and the mechanical properties of repair mortars and their compatibility with the base concrete are significant aspects in the field of repairing of damaged concrete structures. The bond strength parameter of materials is one of the important properties in the selection of repair mortars. In the current Experimental studies, the bond strength of 7 types of cement base mortars consisting Nano-Silica (NS), Micro-Silica (SF) and Polyvinyl Alcohol (PVA) fibers have been tested on base concrete according to ASTM C882 standard. The base concrete is made of fiber concrete with a target compressive strength of 45 MPa and consisting macrosynthetic fibers. The workability of fiber concrete was 120 mm, and the method of curing the samples was done as the wet method. The obtained results indicate that all 7 types of repair materials of this research were compatible with the base concrete and the sample with the combination of PVA fibers and Nano-Silica in cement-based mortars has increased the bond strength of the samples by 85% compared to the samples without fibers. The highest bond strength among the samples was related to cement based mortar containing PVA fibers and Nano-silica (PVA0.75NS6) with bond strength equal to 21.83 MPa. Manuscript profile

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