Weight Of Cement Content Research Articles

Performance of black olive oil as permeability reducing admixture in concrete

The study is aimed at improving the permeability aspect of concrete durability. The main reason for black olive oil (BLO) as the choice material relies on its inherent hydrophobic properties. The effect of BLO admixture on strength and permeability properties of concrete grade C30 was experimentally examined. BLO was integrated into the fresh concrete mix at percentages of 0.3%, 0.5%, 0.7% and 1% by weight of cement content and a water-cement ratio of 0.5 was used throughout the study. Compressive and flexural strength, permeability properties in terms of water adsorption, porosity, coefficient of permeability and sorptivity of the concrete samples were investigated after curing in water at 3, 7, 28, 60, 90 and 180days hydration period. The BLO test admixture acted as a workability improving admixture and air entraining admixture in the fresh concrete. The various water permeability parameters of BLO-concrete samples were significantly improved for all the percentage inclusion of BLO. However, the mechanical strength properties of concrete sample containing the admixture decreased steadily with increase in BLO content. The 28days compressive strength of 03%, 05%, 0.7% and 1% BLO concrete samples decreased approximately by 3%, 13%, 6% and 13% respectively.The adverse impact on the strength properties of BLO-concrete mixes attributed to the effect of increased air content and workability induced by the BLO admixture can be compensated by reducing the water-cement ratio. The 0.3% BLO-concrete which exhibited the least reduction in strength and also meeting the design strength required for residential buildings is considered the optimum content.

Experimental investigation on Hybrid Fibre-Reinforced Concrete (HFRC) fracture toughness and impact resistance with partial replacement of nano-silica

This paper focuses on the compressive strength, fracture toughness and impact resistance of hybrid fibre-reinforced concrete. A total of 78 numbers of compressive strength test cubes, 24 numbers fracture Edge Notched Disc Bend (ENDB) specimens, and 20 numbers of impact disc specimens were constructed and tested. The replacement of Nano-silica was kept constant at 2% based on literature. Glass and steel fibres of 50 mm length were used with 1–4% by weight of cement content. Based on the obtained results, Steel Fibre (SF), Glass Fibre (GS) and Nano-Silica (NS) combinations gave better strength and performance in concrete. The observation made herein is that NS reduces the porosity of concrete as verified with the ultrasonic pulse velocity (UPV) test and microstructural studies including Scanning Electron Microscope (SEM) analysis. The results indicate that fibre combinations achieved better fracture toughness and high-impact resistance while maximum compressive strength was attained for 2% NS + 0.5% SF and 0.5% GF combinations.

Effect Factors on Unconfined Compressive Strength of Soil-Cement Columns: The Case Study of Ba Ria, Vung Tau, Vietnam

This paper presents the effect of the curing environment on the unconfined compressive strength of soil-cement samples and in finding the optimum output mix ratio and estimating the effect of silica fume in the admixture. This work is based on the data from the Cai Mep-Thi Vai inter-port road project and results from laboratory experiments. The results show that the specimens with the highest strength were cured in soil, lowered in city water with NaCl 2.5% and then NaCl 5%. The optimum silica fume admixture ratio equals to 1% (in comparison with the weight of cement content).

Determination of high Strength Concrete with Steel Fibre & Silica Fume

In this experimental studies effect on the Properties of concrete by using Silica fume and steel fibre is investigated, the combined effect of silica fume and steel fibre to be determined. The purpose of this work is to obtain a more flexural strength of concrete produced by using both silica fume and steel fibre. Steel fibres with aspect ratio of 80 were used in the experiments. [1] Addition different percentage of steel fibre and different percentage silica fume by weight of cement content. The slump cone method is used to determine workability [2]. Compressive and Flexural strength test were made on hardened concrete specimens. Plain concrete pavements have low flexural strength and strain capacity;By using fibre structural characteristics are improved and also allows reduction of the thickness of the pavement layer. These better properties are considerable and controlled by characteristics of fibre and percentage. The major effect of fibre reinforcement is to delay and prevent from cracking of concrete. This is will reduces the thickness of pavement which is responsible for less maintenance and provides durability. Brittleness of concrete reduced by addition of steel fibre and Silica fume increases the density of concrete. Failure by using steel fibre and silica fume is ductile in nature and without steel fibre and silica fume brittle in nature [2].

Study on Coupling of Glass Powder and Steel Fiber as Silica Fume Replacement in Ultra-High Performance Concrete: Concrete Sleeper Admixture Case Study

To investigate the substitution of silica fume (SF) with the coupling of glass powder (GP) and steel fiber (STF), a concrete sleeper admixture (CSA) contains SF is considered as the reference concrete admixture. The use of high SF content in CSAs has negative effects on concrete rheology. Furthermore, it decreases the extensive use of ultra-high performance concrete (UHPC) in concrete markets that can mainly be caused by the limitation in available resources and the high cost of SF production. The substitution of SF with GP is insufficient; therefore, the possibility of using the coupling of GP and STF as a SF replacement has been researched. In this regard, 0.5%, 1 % and 1.5% steel fiber by concrete volume and 5%, 10% and 15% glass powder and silica fume by weight of cement content have been investigated. It is found that concrete admixture with the coupling of STF and SF improves all the characteristics of the concrete. Additionally, the coupling effects of GP and STF are better than that of the SF and STF. Based on the synthetic consideration of the performance and cost, the combination of 10% GP and 1.5% STF is optimal in case of CSA mechanical performance.

Effects of using rice straw and cotton stalk ashes on the properties of lightweight self-compacting concrete

This paper presents the mechanical properties and microstructure of lightweight self-compacting concrete (LWSCC) incorporating rice straw ash (RSA) and cotton stalk ash (CSA) as a replacement ratio by weight of cement content. Seven concrete mixtures of LWSCC are prepared as a control mix without RSA and CSA. Three mixes are used with 5%, 10% and 20% RSA, and the three remaining mixes contain 5%, 10% and 20% CSA. The pumice lightweight coarse aggregate is used as a replacement for normal weight coarse aggregates with a ratio of 80%. The filling capability, segregation resistance and passing capability of fresh LWSCC are evaluated. Mechanical properties of hardened LWSCC, including compressive strength, splitting tensile strength, flexural strength, density and microstructural analysis, are measured for 28 days. Results show that the workability of LWSCC is decreased as the RSA and CSA ratios increased. By contrast, the hardened properties of LWSCC are increased as the percentages of RSA and CSA increased, except for 20% replacement ratio. The scanning electron microscope analysis shows that 10% of RSA yielded a denser concrete than the control mix.

Efficiency of Fiber Reinforced Concrete Containing Waste Marble dust and Waste Foundry Sand

The study focused on the effect of marble dust 0-10% (MD) by weight of cement content, waste foundry sand 0-30% (WFS) replaced by normal river sand and inclusion of glued steel fibres 0-1.5% (GSF) by volume fraction and also 1.5% of chemical admixture(SP) by weight of binding materials produced the excellent quality of structural concrete. Conversely, the replacement level of WSF can be limited up to 30%, Further, add into the concrete will affect the strength. From the test results observed that the 10% of MP, 20 % of WFS with 1.5% of GSF along with 1.5% of SP in concrete produced the higher compressive strength was 34.20, 39.90 and 42.50 N/mm2 at 7, 28 and 56 days respectively, the strength was increased up to 7.40% than compared to controlled concrete. Also, a higher amount of bending stress was measured from 3.30 to 4.57 MPa at 28 days for various mixes of concrete and the ultrasonic pulse velocity values are recorded between 3630 to 4030 m/sec for various mixes at 28 days. Finally, the durability measurement of RCPT and also material characteristics test on the modulus of elasticity of concrete were studied systematically.

Influence of silica fume on mechanical and fracture properties of high performance concrete

The main aim of this study is to determine the fracture energy of high performance concrete (HPC) containing silica fume (SF). The article presents the investigation on changes of the mechanical properties including compressive strength, splitting tensile strength, modulus of elasticity, fracture energy, and characteristic length of six HPC caused by the addition of SF. Additions of SF into the HPC were 0%, 5%, 10%, 15%, 20% and 25% by weight of cement content. The water/binder ratio was 0.25. The use of SF increased all tested mechanical properties of concrete. The study indicates that the mechanical properties of HPC were improved to a great extent at 28 days when cement used in concrete was replaced by SF. A 10% content of silica fume resulted in a 26% increase in tensile splitting strength, a 13% increase in compression strength and a 5% increase in the static modulus of elasticity. The brittleness of HPC increased with the presence of SF. The findings suggest that SF can effectively replace cement. Nevertheless, it is recommended that the replacement should not exceed 10%.

Influence of Crystalline Admixtures on the Short-Term Behaviour of Mortars Exposed to Sulphuric Acid.

Using durable materials is a sustainable solution for extending the lifetime of constructions. The use of crystalline admixtures makes cementitious materials more durable. They plug pores, capillary tracts and microcracks, blocking the entrance of water due to the formation of crystals that prevent the penetration of liquids. The literature has covered the performance of these admixtures on concrete, but studies on mortars are still scarce. The aim of this study is to investigate the effect of an aggressive environment (sulphuric acid solution—3 wt%) on mortars produced with different percentages of a crystalline admixture (1%, 1.5% and 2% by weight of cement content). Physical and mechanical properties were studied after immersing the mortars in a H2SO4 solution for 90 days. It was found that, after a 90-day sulphuric acid exposure, mortars with the crystalline admixture showed greater compressive strength than the control mortar, besides exhibiting lower mass loss. However, the crystalline admixture did not produce any significant effect on the capillary water absorption coefficient. In a nonaggressive environment, and in the short term, the crystalline admixture did not have a significant effect on the compressive strength, the capillary water absorption coefficient or the ultrasonic pulse velocity.

Factors influencing half-cell potential measurement and its relationship with corrosion level

The purpose of this research was to evaluate the influences of concrete cover, chloride content, compressive strength and moisture content on the half-cell potential measurement in reinforced concrete structure. The relationship between the level of corrosion and the half-cell potential value was also evaluated. Twenty one concrete slabs with the dimensions of 300 × 300 × 100 mm3 and three concrete slabs with the dimensions of 300 × 300 × 125 mm3 were prepared for various experimental cases; that is, three levels of cover (25, 50 and 100 mm), three levels of chloride content (0.6, 1.2 and 1.8% by weight of cement content) and two levels of compressive strength (17.65 and 20.59 MPa). After curing in water for 28 days, the half-cell potential was measured in accordance with the ASTM C879 every week to detect corrosion under wet-dry accelerated until 140 days. The specimens were then broken to observe the corrosion condition of reinforcement inside them. The results showed that the half-cell potential decreased (more negative value) with the increase of chloride content and moisture content but increased (less negative value) with the increase of compressive strength. The influence of concrete cover was still not definitive. The variation of half-cell potential decreased with the increase of concrete cover, chloride content and moisture content. On the other hand, the variation of half-cell potential increased with the increase of compressive strength. The relationship between the level of corrosion and the half-cell potential was found; that is, the level of corrosion increased with the decrease of the half-cell potential.

Eco-Friendly Concrete Containing PET Plastic Waste Aggregate

The experimental program in this investigation focused on studying the properties of concrete containing different percentages of Plastic Wastes Polyethylene Terephthalate (PET) plastic waste as a volumetric replacement to natural coarse aggregate. Different percentages (10%, 20%, 30%, 40%, and 50%) of PET shredded plastic waste from waste PET bottles as a volumetric replacement to natural coarse aggregate and 10% silica fume as a replacement by weight of cement content were used. The properties of these concrete mixes including, workability, dry density, compressive strength, total flexural energy, impact resistance, thermal conductivity at 28 days age and drying shrinkage at 90 days age were studies. The use of plastic waste aggregate in concrete presents various advantages; one of these advantages is that plastic aggregates result in producing lightweight concrete depending on the percentage of plastic waste used. The dry density of concrete containing higher percentage of PET plastic waste of 40% and 50% as a volumetric replacement to natural coarse aggregate, was 1910 and 1850 kg/m3 respectively. Also thermal insulating properties of concrete containing plastic waste aggregate were improved.

Performance of Lightweight Natural-Fiber Reinforced Concrete

Concrete, the most common construction material, has negligible tension capacity. However, a reinforcement material such as natural fibers, can be used to improve the tensile properties of concrete. This paper presents experiments conducted on Super Lightweight Concrete mixed with coconut fibers (SLNFRC). Coconut fibers are regarded as one of the toughest natural fibers to strengthen concrete. Coconut fiber reinforced composites have been considered as a sustainable construction material because the fibers are derived from waste. These wastes, which are available in large quantities in Asia, have to be extracted from the husk of coconut fruits and must pass a mechanical process before being added to a concrete mixture. The Super Lightweight Concrete was made by mixing concrete paste with foam agent that can reduce the overall weight of concrete up to 60% with compressive strength up to 6 MPa. The Super Lightweight Concrete is intended to be used for non-structural walls, as alternative conventional construction materials such as brick walls. The influence of coconut fibers content in increasing the flexural tensile strength of Super Lightweight Concrete was studied in this research. The fiber content studied include 0%, 0.1%, 0.175%, and 0.25% by weight of cement content. Sixteen specimens of SLNFRC mini beams of 60 mm x 60 mm x 300 mm were tested to failure to investigate their flexural strengths. The optimum percent fibers yielding higher tensile strength was found to be 0.175%

Comportamento mecânico de material fresado após processo de estabilização granulométrica e química por meio da incorporação de cimento e cinza de casca de arroz moída

RESUMO Este trabalho objetivou avaliar, através de ensaios laboratoriais, a viabilidade da utilização de material fresado puro e estabilizado (mecânica, granulométrica e quimicamente) em camadas de pavimentos flexíveis. Os materiais fresados são oriundos da BR-290 e da ERS-509 no estado do Rio Grande do Sul. Foi realizada estabilização granulométrica, sendo determinado o teor de 70% de material fresado e 30% de agregado natural, sendo bastante efetiva na elevação do ISC (de 56 para 95% e de 21 para 68%, para o fresado da BR-290 e ERS-509). Para os ensaios compressão simples foram moldados corpos-de-prova cilíndricos de 10x20 cm com diferentes teores de cimento Portland (CP-IV 32), sendo determinados os teores de 4,86% (BR-290) e 5,37% (ERS-569) a partir da resistência à compressão de 2,1 MPa aos 28 dias. A partir dos resultados obtidos, em uma segunda etapa da pesquisa utilizando somente o material fresado da ERS-509, foram moldados corpos de prova para determinação da resistência à compressão, da resistência à tração e do módulo de resiliência; sendo nestes substituído, em massa, o CP-IV em 15, 30 e 50% por cinza de casca de arroz moída (#325 e #500), colocados em câmara úmida por 7, 28 e 160 dias. A análise dos resultados mostrou que para compressão simples e à tração, a substituição de 15% de cimento por CCA se mostrou eficiente, não havendo queda de resistência comparado as amostras de referência. Também fica evidente a eficácia da CCA, apresentando resultados positivos sempre que comparados àquelas misturas somente com o real teor de cimento Portland utilizado, juntamente com o apelo ambiental se torna uma alternativa interessante de utilização em camadas de pavimentos.

Coloured Concrete with Focus on the Properties of Pigments

In this paper the possibilities of colouring concrete and the use of pigments are presented. There are two groups of pigments with respect to its manufacture (organic and inorganic) and three different forms available on market: powder, granulates and slurry. Next to the influences of other concrete components the effects of fine pigment particles on the properties of fresh and hardened concrete are introduced. Because of the higher need of water the workability of each mixture is affected. With the increasing specific surface area of pigment the flow of fresh concrete decreases. On the other hand this characteristic feature causes slightly higher density of concrete matrix which results in better durability. Optimal dosages differs depending on the form of pigment, for powders it is about 5% of the weight of cement content. Higher amounts don ́t bring about higher tinting strength and in the case of more than 10 % its mechanical properties can be negatively affected. An example of colour evaluation as well as utilization of recycled materials as colouring agents are also mentioned.

Study on the Early Hydration of Cement Paste Containing Sodium Chloride

This paper studies the effect of sodium chloride as the additive component in cement paste. Sodium chloride was included at 0.5%, 1%, 1.5%, and 2% by weight of cement content. Analysis on the performance of this reagent was conducted via setting time, compressive strength, and porosity test. Based on the setting time analysis, the inclusion of sodium chloride can extend the initial setting time of cement paste up to 24.91% longer than control specimen. Obstruction on the formation of calcium silicate hydrate gel by sodium and chloride ion was one of the possible causes to this phenomenon. Acceleration on the compressive strength development by sodium chloride was also detected. It appears that sodium chloride was able to de-flocculate the coagulated cement particles and reduced the viscosities of cement slurries; hence resulted in faster early hydration process.

Assessment of Green Inhibitor on the Crystal Structures of Carbonated Concrete

The present paper involves studies of inhibitors on carbonation depth and carboaluminates of concrete which was exposed to accelerated carbonation. Three inhibitors used were; calcium nitrite, ethanolamine and eco-friendly green Bambusa Arundinacea. Concrete mix was designed to be 30 MPa with 0.45 W/C ratios which was chloride contaminated by 1.5% weight of cement content from analytical grade of magnesium chloride salt. Inhibitors additions were 2% and 4% weight of cement content. The results show that Bambusa arundinacea inhibitor distinctively shows lowest level of carbonation. This developed hydrophobic green inhibitor characteristics was able to form impermeable barrier against CO2 gas. Additionally, hemicarboaluminate phases appears at hydration in calcite-containing Portland cement, even in the presence of two inhibitors (calcium nitrite and ethanolamine) which gradually converted to monocarboaluminate. Whereas, Bambusa arundinacea inhibitor causes the saturation of portlandite that maintained Ca/Si ratio above 1.65 and C-S-H remain unaffected by carbonation.

Performance of Self Compacting High Strength Fiber Reinforced Concrete (SCHSFRC)

In this experimental study the changes on some mechanical properties of self compacting concrete specimen produced by silica fume, metakaolin, fly ash and steel fibers were investigated. The main objective of this is to obtain ductile Self Compacting High Strength Concrete (SCHSC) which flows under its own weight and homogeneity while completely filling any formwork and passing around congested reinforcement. The Self Compacting High Strength Concrete produced by using silica fume, metakaolin, fly ash, steel fibers and Polycarboxylatether base superplasticizer. Three types of steel fibers were used in the experiments and volume fractions of steel fiber were 0.5% to 4.0 %. Addition of silica fume, metakaolin and fly ash into the concrete were 2.5 %, 2.5 % and 10 % by weight of cement content respectively. Water/cement ratio was 0.29. Compressive strength and split tensile strength tests were made on hardened concrete specimens. Keywords-Compressive Strength, Fly Ash, High Strength Concrete (HSC), High Strength Fiber Reinforced Concrete (HSFRC), Metakaolin, Silica fume, Split Tensile Strength, Steel Fibres. I. Introduction Construction of durable concrete structures requires skilled labor for placing and compacting concrete. Self Compacting Concrete achieves this by its unique fresh state properties. In the plastic state, it flows under its own weight and homogeneity while completely filling any formwork and passing around congested reinforcement. In the hardened state, it equals or excels standard concrete with respect to strength and durability. This work is aimed to study the performance of steel fiber reinforced self compacting concrete as plain self compacting concrete is studied in depth but the fiber reinforced self compacting concrete is not studied to that extent. The main objective of this study is to optimize the Steel Fiber Reinforced Self Compacting High Strength Concrete (SFRSCHSC) in the hardened state. But the literature indicates that some studies are available on plain SCC but sufficient literature is not available on Steel Fiber Reinforced Self Compacting High Strength Concrete (SFRSCHSC) with different mineral admixtures. Hence an attempt is made in this work to study the mechanical properties of both plain Self Compacting High Strength Concrete (SCHSC) and SFRSCC.

Combine Effect of Metakaolin, Fly Ash and Steel Fiber on Mechanical Properties of High Strength Concrete

In this experimental study the changes on some mechanical properties of concrete specimens produced by Metakaolin, fly Ash and steel fibers were investigated. The main objective of this work is to obtain a more ductile high strength concrete produced by using Metakaolin, Fly Ash and Steel Fiber. Three types of steel fibers were used in the experiments and volume fractions of steel fiber were 0.5% to 4.0 %. Addition of metakaolin and fly ash into the concrete were 5 % and 10 % by weight of cement content respectively. Water/cement ratio was 0.27. Compressive strength and split tensile strength tests were made on hardened concrete specimens. The use of metakaolin increased mechanical strength of concrete. On the other hand, the addition of steel fiber into concrete improves ductility of high strength concrete significantly. Keywords-Compressive Strength, Fly Ash, High Strength Concrete (HSC), High Strength Fiber Reinforced Concrete (HSFRC), Metakaolin, Split Tensile Strength, Steel Fiber.

Combined effect of silica fume and steel fiber on the mechanical properties of high strength concretes

In this experimental study, the changes on some mechanical properties of concrete specimens produced by using silica fume and steel fiber were investigated. The main objective of this work is to obtain a more ductile high strength concrete produced by using both silica fume and steel fiber. Two types of steel fibers with aspect ratios (fiber length/fiber diameter) of 65 and 80 were used in the experiments and volume fractions of steel fiber were 0.5% and 1%. Additions of silica fume into the concrete were 0%, 5%, 10% and 15% by weight of cement content. Water/cement ratio was 0.38 and the reference slump was 120 ± 20 mm. Slump test for workability, air content and unit weight tests were performed on fresh concretes. Compressive strength, splitting tensile strength and flexural strength tests were made on hardened concrete specimens. Load–deflection curves and toughness of the specimens were also obtained by flexural test performed according to ASTM C1018 standards. Flexural tests on beam specimens were achieved using a closed loop deflection-controlled testing machine. The use of silica fume increased both the mechanical strength and the modulus of the elasticity of concrete. On the other hand, the addition of steel fiber into concrete improves toughness of high strength concrete significantly. As the steel fiber volume fraction increases, the toughness increases, and high values of aspect ratios give higher toughness. The toughness of high strength steel fiber concrete depends on silica fume content, the fiber volume fraction and the fiber aspect ratio.