scholarly journals Rheological Behavior and Microstructure Characteristics of SCC Incorporating Metakaolin and Silica Fume

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2576 ◽  
Author(s):  
Gang Ling ◽  
Zhonghe Shui ◽  
Tao Sun ◽  
Xu Gao ◽  
Yunyao Wang ◽  
...  
Keyword(s):  
Pore Structure ◽  
Silica Fume ◽  
Mechanical Performance ◽  
Free Water ◽  
Hydration Product ◽  
Replacement Ratio ◽  
Microstructure Characteristics ◽  
Beneficial Effects ◽  
Slump Flow ◽  
Strength And Durability

This study explores the effects of metakaolin (MK) and silica fume (SF) on rheological behaviors and microstructure of self-compacting concrete (SCC). The rheology, slump flow, V-funnel, segregation degree (SA), and compressive strength of SCC are investigated. Microstructure characteristics, including hydration product and pore structure, are also studied. The results show that adding MK and SF instead of 4%, 6% and 8% fly ash (FA) reduces flowability of SCC; this is due to the fact that the specific surface area of MK and SF is larger than FA, and the total water demand increases as a result. However, the flowability increases when replacement ratio is 2%, as the small MK and SF particles will fill in the interstitial space of mixture and more free water is released. The fluidity, slump flow, and SA decrease linearly with the increase of yield stress. The total amount of SF and MK should be no more than 6% to meet the requirement of self-compacting. Adding MK or SF to SCC results in more hydration products, less Ca(OH)2 and refinement of pore structure, leading to obvious strength and durability improvements. When the total dosage of MK and SF admixture is 6%, these beneficial effects on workability, mechanical performance, and microstructure are more significant when SF and MK are applied together.

Research on Properties of Low Grade Cement-Based Composite Materials Modified by Silica Fume

2012 ◽  
Vol 174-177 ◽  
pp. 751-756
Author(s):  
Zi Fang Xu ◽  
Ming Xu Zhang ◽  
Jin Hua Li
Keyword(s):  
Silica Fume ◽  
Mechanical Performance ◽  
Raw Materials ◽  
Cement Matrix ◽  
Hardened Cement ◽  
Low Grade ◽  
X Ray ◽  
Matrix Microstructure ◽  
Nano Powder ◽  
Strength And Durability

In order to notably improve the mechanical properties and durability of low-grade cement-based material, superfine silica fume was used to modify the cement-based composite based on special perfomance and effects of nano powder. The mechanical performance and durability were investigated.Then the phase compositions,microstructure and morphologies of as-received cement-based composite were studied by X-ray Diffractometer、TGA-DTA and SEM. The results show that： the best formula of raw materials is 1:1:0.025:0.015, and hydration can be accelerated and increasing of hydration products is observed after modification. In the hardened cement matrix, microstructure is very compacted and C-S-H gel forms densed structure, so the structure defect is notably reduced. This means that both strength and durability of cement-based composite are notably improved by the addition of superfine silica fume.

scholarly journals Development of Eco-Friendly Cement Using a Calcium Sulfoaluminate Expansive Agent Blended with Slag and Silica Fume

2021 ◽  
Vol 11 (1) ◽  
pp. 394
Author(s):  
Taewan Kim ◽  
Ki-Young Seo ◽  
Choonghyun Kang ◽  
Tak-Kee Lee
Keyword(s):  
Silica Fume ◽  
Mechanical Performance ◽  
Hydration Product ◽  
Early Age ◽  
Low Carbon ◽  
Calcium Sulfoaluminate ◽  
Mixing Ratios ◽  
Expansive Agent ◽  
Binder Ratio

This is an experimental study on the development of a low-carbon, eco-friendly cement containing a calcium sulfoaluminate expansive agent (CSAe), slag, and silica fume (SF). The cement to be developed has a low water/binder ratio (w/b) of 0.5 and is designed to be used for structural purposes, with focus on its mechanical performance. CSAe, slag, and SF were mixed at various mixing ratios. The main hydration product of the slag-based CSAe cement in the experiment was ettringite. Substituting less than 30% of CSAe showed a sufficient level of mechanical performance; that is, the material could be used as structural cement. SF controlled the excessive expansion of CSAe. However, since the developed slag-CSAe-SF cement has low early age (1 d) strength, follow-up research is needed for improvement.

Experiment Study on Mechanics and Pore Structure of Steel Fibre Reinforced Concrete

2010 ◽  
Vol 150-151 ◽  
pp. 825-828
Author(s):  
Yan Wang ◽  
Di Tao Niu ◽  
Yuan Yao Miao ◽  
Nai Qi Jiao
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Reinforced Concrete ◽  
Pore Structure ◽  
Steel Fibre ◽  
Fibre Reinforced Concrete ◽  
Experiment Study ◽  
Steel Fibre Reinforced Concrete ◽  
Mercury Intrusion ◽  
Strength And Durability

The concrete microstructure can affect its macroscopic properties, such as the strength and durability, etc. Based on the experimental study of cube compressive strength of steel fibre reinforced concrete, splitting tensile strength, flexural strength, and using by mercury intrusion method to test the pore structure of steel fibrous, this paper analyzes the influence of fibre on concrete pore structure. And then on mechanical properties of concrete from microcosmic perspective.

Mechanical Performance of Steam-Cured Self-Compacting Concrete Incorporating Silica Fume and Limestone Powder

2021 ◽  
Vol 56 ◽  
pp. 111-122
Author(s):  
Youcef Ghernouti ◽  
Bahia Rabehi ◽  
Sabria Malika Mansour
Keyword(s):  
Heat Treatment ◽  
Silica Fume ◽  
Mechanical Performance ◽  
Limestone Powder ◽  
Maximum Temperature ◽  
Self Compacting Concrete ◽  
Curing Period ◽  
Heat Treated ◽  
Binder Ratio ◽  
Mechanical Strengths

In this paper, influence of heat treatment on evolution of mechanical strengths at early age, less than 24hours of self-compacting concretes containing limestone powder and silica fume as fine materials was investigated experimentally. Two compositions of self-compacting concrete have been studied; the first is elaborated with silica fume addition and the second with limestone powder, each mixture were prepared with a constant water/binder ratio of 0.39. Concrete samples were either cured in water at (23±1°C), or steam cured at 65°C maximum temperature over six hours (6h) curing period. Tests of mechanical strengths were performed on specimens cooled down slowly to room temperature after heating.The obtained results show that all self-compacting mixtures exhibited satisfying fresh properties and check EFNARC specifications of self-compacting concrete (slump flow diameter higher than 650mm, L-box ratio higher than 80% and sieve stability less than 17%).Mechanical strengths of concrete containing limestone addition are slightly lower than those of concrete based on silica fume at all ages. Moreover, heat treatment generates an improvement of compressive and flexural strength. Interesting compressive strengths are obtained. At 24 hours, after heat treatment, the strengths are already greater than 35 MPa. The values ​​are 37 MPa and 40 MPa for self-compacting concrete containing limestone powder and silica fume respectively compared to 40 MPa and 46 MPa obtained at 7 days for the corresponding non-heat treated concretes. Compressive strength gain of SCCs mixtures with limestone powder and with silica fume, undergoing heat treatment at the age of 24hours is 85% and 75% respectively compared to SCCs mixtures cured in water.

scholarly journals Cement-Based Materials Containing Graphene Oxide and Polyvinyl Alcohol Fiber: Mechanical Properties, Durability, and Microstructure

Nanomaterials ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 638 ◽  
Author(s):  
Wenguang Jiang ◽  
Xiangguo Li ◽  
Yang Lv ◽  
Mingkai Zhou ◽  
Zhuolin Liu ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Flexural Strength ◽  
Polyvinyl Alcohol ◽  
Mechanical Strength ◽  
Mechanical Performance ◽  
Control Sample ◽  
Corrosion Condition ◽  
Cement Based Materials ◽  
Strength And Durability ◽  
Pva Fiber

The influence of graphene oxide (GO) and polyvinyl alcohol (PVA) fiber on the mechanical performance, durability, and microstructure of cement-based materials was investigated in this study. The results revealed that compared with a control sample, the mechanical strength and durability of cement-based materials were significantly improved by adding PVA fiber and GO. The compressive and flexural strength at 28 d were increased by 30.2% and 39.3%, respectively. The chloride migration coefficient at 28 d was reduced from 7.3 × 10−12 m2/s to 4.3 × 10−12 m2/s. Under a sulfate corrosion condition for 135 d, the compressive and flexural strength still showed a 13.9% and 12.3% gain, respectively. Furthermore, from the Mercury Intrusion Porosimetry (MIP) test, with the incorporation of GO, the cumulative porosity decreased from more than 0.13 cm3/g to about 0.03 cm3/g, and the proportion of large capillary pores reduced from around 80% to 30% and that of medium capillary pores increased from approximately 20% to 50%. Scanning electron microscope (SEM) images showed a significant amount of hydration products adhering to the surface of PVA fiber in the GO and PVA fiber modified sample. The addition of GO coupling with PVA fiber in cement-based materials could promote hydration of cement, refine the microstructure, and significantly improve mechanical strength and durability.

scholarly journals Rheology, Strength and Durability Characteristics of Alccofine Blended Fibre Reinforced Self Consolidating Concrete

2018 ◽  
Vol 7 (3.12) ◽  
pp. 209
Author(s):  
Bletty Baby ◽  
Jerry Anto ◽  
Basil Johny ◽  
Sreenath S
Keyword(s):  
Steel Fibre ◽  
Flow Characteristics ◽  
Strength Degradation ◽  
Fibre Content ◽  
Split Tensile Strength ◽  
Self Consolidating Concrete ◽  
Slump Flow ◽  
Strength Tests ◽  
Hardened Properties ◽  
Strength And Durability

In this study, observations were made on the effect of blending cement with fly ash and Alccofine on the fresh and hardened properties of micro steel fibre reinforced self-consolidating concrete (SCC). SCC mixes were prepared based on EFNARC guidelines. Blending has been done by replacing 5%, 10% and 15% of cement with Alccofine. Slump flow, L-box and V-funnel tests were conducted to study the flow characteristics of SCC. Compressive strength, split tensile strength, and flexural strength tests were performed to assess the strength characteristics. It was observed that the SCC with 10% replacement of cement with Alccofine showed better results than the other mixes. Further, the modification of the optimum blend with 10% Alccofine was made by adding variable percentages (0.5%, 1% and 1.5% by volume) of micro steel fibres and strength tests were conducted to optimise the fibre content. The strength degradation of the SCC with optimum Alccofine and fibre content exposed to alkaline, chloride and sulphate solutions was also studied.

scholarly journals Research on Mechanical Performance & Behaviour of Geopolymer Concrete Subjected to Elevated Temperatures

2019 ◽  
Vol 8 (2S8) ◽  
pp. 883-887
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Silica Fume ◽  
Elevated Temperatures ◽  
Mechanical Performance ◽  
Geopolymer Concrete ◽  
Sem Images ◽  
Before And After ◽  
Alkaline Conditions ◽  
Compressive Strength Of Concrete

The investigative studies on mechanical performance & behaviour, of Geopolymer Concrete (GPC) before and after the exposure to elevated temperatures (of 200 0 C -1000 0 C with an increment of 100 0 C). Indicate that the GPC Specimens Exhibited better Compressive strength at higher temperatures than that of those made by regular OPC Concrete with M30 Grade. The chronological changes in the geopolymeric structure upon exposure to these temperatures and their reflections on the thermal behaviour have also been explored. The SEM images indicate GPC produced by fly ash , metakaolin and silica fume, under alkaline conditions form Mineral binders that are not only non-flammable and but are also non-combustible resins and binders. Further the Observations drawn disclose that the mass and compressive strength of concrete gets reduced with increase in temperatures.

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