scholarly journals Prevention of Autogenous Shrinkage in High-Strength Mortars with Saturated Tea Waste Particles

Materials ◽  
2019 ◽  
Vol 12 (17) ◽  
pp. 2654 ◽  
Author(s):  
Sadam Hussain Jakhrani ◽  
Jae Suk Ryou ◽  
Atta-ur-Rehman ◽  
In Kyu Jeon ◽  
Byeong Hun Woo ◽  
...  
Keyword(s):  
Silica Fume ◽  
High Performance ◽  
Autogenous Shrinkage ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Cement Composites ◽  
Tea Waste ◽  
Long Time ◽  
Waste Particles ◽  
Mechanical Strengths

The purpose of this study was to prevent early age autogenous shrinkage in high-strength mortars with saturated tea waste particles. In general, high strength and high performance concretes are made with low water/binder ratios; hence, they are susceptible to shrink at early ages. This shrinkage occurs due to self-desiccation that leads to autogenous shrinkage. To overcome self-desiccation problems in high-strength cement composites, it is necessary to keep the composites moist for a long time. Pre-saturated porous lightweight aggregates and super absorbent polymers are the most commonly used materials in high-strength cement composites to keep them moist for a long time; however, in this study, porous tea waste particles were used to keep the cement mortars moist. Pre-saturated tea waste particles were used in two different size proportions, making up as much as 3% of the volume of the binder. Moreover, commonly used lightweight aggregate (perlite) was also used to compare the outcomes of specimens made with tea waste particles. Different parameters were observed, such as, flow of fresh mortars, autogenous shrinkage, mechanical strengths and microstructure of specimens. The addition of tea waste and perlite particles in mortars made with Ordinary Portland cement (OPC) as the only binder, showed a reduction in flow, autogenous shrinkage and mechanical strengths, as compared to mixes made with partial addition of silica fume. Although, the use of silica fume improved the mechanical strength of specimens. Moreover, the use of saturated tea waste and perlite particles also improved the microstructure of specimens at an age of 28 days. The results revealed that the saturated tea waste particles have the ability to prevent autogenous shrinkage but they reduce strength of high-strength mortars at early ages.

Early-Age Autogenous Shrinkage of High-Performance Concrete Columns by Embedded Fiber Bragg-Grating Sensor

2009 ◽  
Vol 419-420 ◽  
pp. 1-4 ◽  
Author(s):  
Ying Wei Yun ◽  
Ii Young Jang ◽  
Seong Kyum Kim ◽  
Seung Min Park
Keyword(s):  
Fiber Bragg Grating ◽  
High Performance ◽  
High Performance Concrete ◽  
Construction Material ◽  
Autogenous Shrinkage ◽  
Strain Sensor ◽  
Bragg Grating ◽  
Early Age ◽  
Long Time ◽  
Sensor Temperature

High-performance concrete (HPC) as a promising construction material has been widely used in infrastructures and high-rise buildings etc. However, its pretty high autogenous shrinkage (AS) especially in its early age becomes one of the key problems endangering long-time durability of HPC structures. This paper carried out the early age AS research of large scaled HPC column specimens by embedded Fiber Bragg-Grating (FBG) strain sensor. Temperature compensation for FBG strain sensor by thermocouple was also attempted in this paper, and the results were reasonable and acceptable comparing with the result compensated by FBG temperature sensor. Reinforcement influence, size effect and temperature effect on HPC AS were also analyzed respectively in this paper.

New Model for Concrete Creep and Shrinkage Prediction and its Application

2016 ◽  
Vol 249 ◽  
pp. 125-130 ◽  
Author(s):  
Vojtěch Kolínský ◽  
Jan L. Vítek
Keyword(s):  
Prediction Models ◽  
Concrete Strength ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
New Model ◽  
Software Products ◽  
Internal Parameters ◽  
Environment Temperature ◽  
Long Time ◽  
Creep And Shrinkage

At the beginning of this year prof. Z. P. Bažant and his team published a new numerical model for predicting creep and shrinkage in concrete structures. Model, named B4, is conceptually based on the previous version B3. While early prediction models were based mostly on classical concrete composition, the new model allows for observation the variability of modern concrete compositions, i.e. the effects of admixtures, various aggregate types and increasing concrete strength. The model also captures the effects of environment temperature, multi-decade prediction and autogenous shrinkage. This is important for concretes that are produced in Czech Republic and have higher, but not high strength (about 50 MPa). The model also allows to determine internal parameters according to experimental measurements on laboratory specimens or structural members. Therefore it is possible to refine the prediction of the behavior of structures made of this concrete in the long time periods. However, the increased number of input parameters leads to a higher complexity and it is necessary to have computational tools for practical model application. To provide the model to wider engineering community open structure computational program (in MATLAB environment) was created. Software is freely available for download on the internet. Description of the innovations of the model B4 and demonstration of its relatively simple applications using newly developed software products is a subject of this paper.

Some characteristics of high-strength structural concrete

1991 ◽  
Vol 18 (5) ◽  
pp. 885-889 ◽  
Author(s):  
J. A. Bickley ◽  
J. Ryell ◽  
C. Rogers ◽  
R. D. Hooton
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Performance ◽  
High Strength ◽  
Standard Test ◽  
Technical Note ◽  
Concrete Technology ◽  
Chloride Permeability ◽  
Strength Concrete ◽  
Low Humidity

The 68-storey Scotia Plaza tower in Toronto is an outstanding example of the use of concrete technology to achieve high-performance high-strength concrete. Cementitious hydraulic slag, silica fume, and a superplasticizer were combined with CSA type-10 Portland cement and high-quality aggregates to produce very workable high-strength concrete. During the course of construction, data were published suggesting the possibility of the strength regression of some silica fume concretes after long exposure to low humidity, the determinations being made on standard test cylinders. Tests were, therefore, made at ages of 1 year and 2 years on specimens drilled from columns in the structure. This technical note gives details of the laboratory examination and testing of these specimens. Key words: high strength, slag, silica fume, permeability, rapid chloride permeability, petrographic examination, superplasticizers.

Evaluation of Setting Time in Ultra High Performance Concrete

2012 ◽  
Vol 525-526 ◽  
pp. 621-624
Author(s):  
Sung Wook Kim ◽  
Jung Jun Park ◽  
Doo Youl Yoo ◽  
Young Soo Yoon
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Setting Time ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Initial Crack ◽  
Test Method ◽  
Plastic State ◽  
Ultra High Performance Concrete ◽  
Confining Stress

Ultra high performance concrete (UHPC), characterized by a high strength and high ductility, is also subjected to large shrinkage due to its low water-to-binder ratio and its large content in high fineness materials. The large amount of autogenous shrinkage of UHPC can induce crack on structural member when it was restrained with reinforcement and form. However, shrinkage of UHPC in plastic state is not generating confining stress, which is the main cause of initial crack. Normally, the setting time in concrete is an index to distinguish shrinkage which occur confining stress or not. An estimation of setting time is conducted in compliance with ASTM C 403 till now however, that test standard reveals error of results due to discordance of test condition as following with concrete type. This study therefore evaluated setting time of UHPC through the modified test method which was proposed by KICT. Test results and analyses proved a discrepancy of setting time between ASTM and proposed method. The proposed method put faith in evaluation of setting time in accordance with UHPC.

Basic Study of PK Fiber Tire Cord3

2007 ◽  
Vol 35 (4) ◽  
pp. 317-325 ◽  
Author(s):  
Yugo Zuigyo ◽  
Masahiko Yamamoto
Keyword(s):  
High Performance ◽  
High Strength ◽  
Laboratory Evaluation ◽  
High Modulus ◽  
Tire Cord ◽  
Basic Study ◽  
Performance Requirements ◽  
Simple Processing ◽  
Long Time ◽  
Excellent Adhesion

Abstract Rayon, nylon, and polyester have been used for a long time as general tire reinforcements. Recently application of p-aramid fiber, which has high tenacity and high modulus properties, is gradually increasing in order to satisfy high-performance requirements, large tires, and tire weight reduction. However, in working with high-strength and high-modulus fibers such as p-aramid it is normally difficult to obtain excellent adhesion with simple processing methods and their fatigue resistances are not good. This time we have focused on a new high-tenacity and high-modulus “polyketone” fiber obtained by gel-spun technology and performed a basic study in tire cord application. Through laboratory evaluation, we have confirmed that polyketone cord fiber has excellent adhesion, comparable with rayon and nylon, and good fatigue resistance in comparison with rayon. In addition, through its tire evaluation as a body-ply cord and cap-ply cord for PCR tires, we have confirmed its performance advantage in comparison to current tire cords.

Nanoadditives - Future of High Performance Concrete

2017 ◽  
Vol 908 ◽  
pp. 83-87
Author(s):  
Martin Labaj ◽  
Jaroslav Válek ◽  
Tomáš Jarolím ◽  
Lucia Osuská
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Concrete Surface ◽  
Cement Stone ◽  
Hardened Cement ◽  
Concrete Technology ◽  
High Quality ◽  
Long Time ◽  
The Impact

These days it is almost impossible to imagine the technology of high performance concrete without the use of any kind of additive. Whether it is a material capable of achieving high strength, excellent mobility of the fresh mix without losing cohesion or producing high quality architectural concrete surface, microadditives have their certain place for a long time now. Although the research in this field still has something to offer, it does not hurt to try to consider the future and imagine the path that will be taken in the production of high performance concrete of next generation. The article deals with the possibility of using nanoparticles in concrete technology. These materials can actively participate in the creation of very high-quality cement stone. In addition, due to the extreme reactivity of nanoparticles, these reactions can take place almost immediately after the onset of hydration and during its first hours. The experimental part of the paper assesses the impact of nanoparticles on selected properties of fresh cement paste and hardened cement mortar. In all cases, there was a positive effect and it has been demonstrated that nanoparticles may eventually create a new category of high performance concrete additives.

Technology of Ultra-High Strength / High Performance Concrete Applied to Guangzhou Xita Tower Construction

2009 ◽  
Vol 405-406 ◽  
pp. 1-4 ◽  
Author(s):  
Hao Wen Ye
Keyword(s):  
High Performance ◽  
High Performance Concrete ◽  
Autogenous Shrinkage ◽  
High Strength ◽  
Hardened Concrete ◽  
High Rise ◽  
Slump Flow ◽  
Mix Proportion ◽  
New City ◽  
Pumping Equipment

This paper introduces development and application of ultra-high strength/high performance concrete in construction of the Xita tower high-rise building at Zhujiang New City of Guangzhou, China. The goal of the concrete construction in the Xita Tower project will be realized via research of mix proportion and optimization of pumping equipment. In regard to mix proportion of concrete, low water/cement (W/C) ratio, low water content lower than 150 kg/m3 and employment of superplasticizer are essential to acquire high strength. A series of parameters have been measured to research workability of concrete from C70 to C90, such slump, slump flow, flow time from inverted cone, L-box flow, and bleeding under pressure et al. Properties of hardened concrete should also be considered, including durability, autogenous shrinkage caused cracking, and fire resistance.

scholarly journals Performance Comparison between Densified and Undensified Silica Fume in Ultra-High Performance Fiber-Reinforced Concrete

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3901 ◽  
Author(s):  
Sung-Hoon Kang ◽  
Sung-Gul Hong ◽  
Juhyuk Moon
Keyword(s):  
Reinforced Concrete ◽  
Silica Fume ◽  
High Performance ◽  
High Strength ◽  
Performance Comparison ◽  
Fiber Reinforced Concrete ◽  
Hydration Reaction ◽  
Fiber Reinforced ◽  
Dust Generation ◽  
High Performance Fiber

Silica fume (SF) is a key ingredient in the production of ultra-high performance fiber-reinforced concrete (UHPFRC). The use of undensified SF may have an advantage in the dispersion efficiency inside cement-based materials, but it also carries a practical burden such as high material costs and fine dust generation in the workplace. This study reports that a high strength of 200 MPa can be achieved by using densified SF in UHPFRC with Portland limestone cement. Additionally, it was experimentally confirmed that there was no difference between densified and undensified SFs in terms of workability, compressive and flexural tensile strengths, and hydration reaction of the concrete, regardless of heat treatment, because of a unique mix proportion as well as mixing method for dispersing agglomerated SF particles. It was experimentally validated that the densified SF can be used for both precast and field casting UHPFRCs with economic and practical benefits and without negative effects on the material performance of the UHPFRC.

Study of High Strength Concrete Using Microsilica

2018 ◽  
Vol 6 (8) ◽  
pp. 414 ◽  
Author(s):  
Ramanpreet Singh ◽  
Gurprit Singh Bath ◽  
Manjeet Bansal
Keyword(s):  
Silica Fume ◽  
High Strength Concrete ◽  
High Performance ◽  
High Performance Concrete ◽  
High Strength ◽  
Copper Slag ◽  
Strength Concrete ◽  
Construction Company ◽  
Four Levels ◽  
High Level

The framework of bridges, buildings, roads etc. need concrete. The concrete which is being used is not able to fulfil the contemporaneous needs. In India High Strength Concrete (HSC) is preferred for manufacturing practices and at the same time High Performance Concrete is used at high level. The properties of HSC are improved like mechanical and durability are improved by using silica fume in concrete. HSC has made the work of construction company more rewarding to design tall, long and light structures. HSC is helpful in designing buildings with good number of floors, wide area bridges and slim structure. The products like fly-ash, copper slag, silica fume etc. are produced by industries which leads to various environmental problems. The experiment on silica was done which stated that no strength is lost in silica-fume concretes. The experiment comprises four levels of silica-fume at the rate of 0%, 5.5%, 8.0%,9.5% and 11.0% which results high strength concrete.

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