scholarly journals Effect of Aggregate Types on the Mechanical Properties of Traditional Concrete and Geopolymer Concrete

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1110
Author(s):  
Hani Alanazi
Keyword(s):  
Mechanical Properties ◽  
Laser Scanning ◽  
Large Scale ◽  
Geopolymer Concrete ◽  
Coarse Aggregates ◽  
Concrete Mixtures ◽  
Different Types ◽  
Quartz Aggregates ◽  
Large Scale Tests ◽  
Physical And Chemical

For the same concrete quality, different types of coarse aggregates may result in different mechanical properties. This paper presents a study on the effect of aggregate types on the mechanical properties of two concretes, namely, geopolymer concrete (GP) and traditional Portland cement (TC) concrete. The mechanical properties were investigated through several large-scale tests. Moreover, scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and laser scanning microscope (LSM) images were obtained to study the microstructure of tested mixes. The results revealed that the aggregate type has different effects on the mechanical properties of TC and GP, as they were behaving opposite to quartz and limestone aggregates. Microstructure analysis further confirmed the growth of well-bonded regions between the paste and aggregate in the GP with limestone aggregates, and the formation of several weak interfacial zones in concrete mixtures made with quartz aggregates. It was concluded that the mechanical properties of GP are very sensitive to the stiffness of aggregate, concentrations of stress, and the physical and chemical reactions occurring in the interfacial transition zone which may lead to improved or weakened bond strength between paste and aggregates.

scholarly journals LOADS ON WIND TURBINES ACCESS PLATFORMS WITH GRATINGS

2011 ◽  
Vol 1 (32) ◽  
pp. 65
Author(s):  
Thomas Lykke Andersen ◽  
Peter Frigaard ◽  
Michael R Rasmussen ◽  
Luca Martinelli
Keyword(s):  
Drag Coefficient ◽  
Wind Turbine ◽  
Wind Turbines ◽  
Large Scale ◽  
Peak Load ◽  
Multiplication Factor ◽  
Preliminary Results ◽  
Different Types ◽  
The Many ◽  
Large Scale Tests

The present paper deals with loads on wind turbine access platforms. The many planned new wind turbine parks together with the observed damages on platforms in several existing parks make the topic very important. The paper gives an overview of recently developed design formulae for different types of entrance platforms. Moreover, the paper present new results on loads on grates based on both drag coefficient measurements and preliminary results on slamming from large scale tests. As expected both investigations show that platforms with grates give a significant reduction in the loads compared to closed plate platforms. The grate multiplication factor, defined as the peak load on the grate platform relative to the peak load on a closed plate platform was found approximately equal to the solidity of the grate.

Performance Enhancement of Recycled Aggregate Concrete – An Experimental Study

2021 ◽  
Author(s):  
Sivamani Jagan ◽  
Thurvas Renganathan Neelakantan ◽  
Palaniraj Saravanakumar
Keyword(s):  
Mechanical Properties ◽  
Experimental Study ◽  
Elastic Modulus ◽  
Performance Enhancement ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete ◽  
Coarse Aggregates ◽  
Durability Properties ◽  
Concrete Mixtures

Extensive studies have been performed on the mechanical and durability properties of the concrete prepared with recycled coarse aggregates (RCA), however, only modest consideration has been given to the studies on the behaviour of RAC prepared by alternative mixing approach techniques. This study presents the mechanical properties of the recycled aggregate concrete (RAC) with different percentages of RCA prepared by normal mixing approach (NMA), two-stage mixing approach (TSMA) and sand enveloped mixing approach (SEMA) techniques. The manufactured concrete mixtures were tested for compression, tension, flexure and elastic modulus at 7, 28 and 90 days. The results indicate that the mechanical properties of the RAC (with 100% of RCA) prepared through TSMA and SEMA were improved by 9.36 and 12.14% at 28 days. Perhaps, prolonged curing to TSMA and SEMA mixtures improved the mechanical properties of the RAC that is nearly equal to normal aggregate concrete (NAC) prepared by NMA.

scholarly journals Development of Heavyweight Self-Compacting Concrete and Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1035 ◽  
Author(s):  
Afsaneh Valizadeh ◽  
Farhad Aslani ◽  
Zohaib Asif ◽  
Matt Roso
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Tensile Tests ◽  
Offshore Structures ◽  
Experimental Program ◽  
Geopolymer Concrete ◽  
Self Compacting Concrete ◽  
Coarse Aggregates ◽  
Maximum Compressive Strength ◽  
Heavyweight Concrete

Heavyweight self-compacting concrete (HWSCC) and heavyweight geopolymer concrete (HWGC) are new types of concrete that integrate the advantages of heavyweight concrete (HWC) with self-compacting concrete (SCC) and geopolymer concrete (GC), respectively. The replacement of natural coarse aggregates with magnetite aggregates in control SCC and control GC at volume ratios of 50%, 75%, and 100% was considered in this study to obtain heavyweight concrete classifications, according to British standards, which provide proper protection from sources that emit harmful radiations in medical and nuclear industries and may also be used in many offshore structures. The main aim of this study is to examine the fresh and mechanical properties of both types of mixes. The experimental program investigates the fresh properties of HWSCC and HWGC through the slump flow test. However, J-ring tests were only conducted for HWSCC mixes to ensure the flow requirements in order to achieve self-compacting properties. Moreover, the mechanical properties of both type of mixes were investigated after 7 and 28 days curing at an ambient temperature. The standard 100 × 200 mm cylinders were subjected to compressive and tensile tests. Furthermore, the flexural strength were examined by testing 450 × 100 × 100 mm prisms under four-point loading. The flexural load-displacement relationship for all mixes were also investigated. The results indicated that the maximum compressive strength of 53.54 MPa was achieved by using the control SCC mix after 28 days. However, in HWGC mixes, the maximum compressive strength of 31.31 MPa was achieved by 25% magnetite replacement samples. The overall result shows the strength of HWSCC decreases by increasing magnetite aggregate proportions, while, in HWGC mixes, the compressive strength increased with 50% magnetite replacement followed by a decrease in strength by 75% and 100% magnetite replacements. The maximum densities of 2901 and 2896 kg/m3 were obtained by 100% magnetite replacements in HWSCC and HWGC, respectively.

scholarly journals The Utilization of Recycled Masonry Aggregate and Recycled EPS for Concrete Blocks for Mortarless Masonry

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1923 ◽  
Author(s):  
Tereza Pavlu ◽  
Kristina Fortova ◽  
Jakub Divis ◽  
Petr Hajek
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Masonry Wall ◽  
Expanded Polystyrene ◽  
Mechanical And Thermal Properties ◽  
Concrete Mixtures ◽  
Wall Structures ◽  
Different Types ◽  
Concrete Blocks ◽  
Recycled Masonry

The main aim of this paper is to carry out the environmentally based enhancement of a concrete mixture containing recycled materials whilst considering natural resource consumption as well as mechanical and thermal property levels. The developed concrete is intended to be used in mortarless masonry wall structures. Ten concrete mixtures with different types and replacement rates of recycled masonry aggregate and recycled expanded polystyrene were prepared, and their mechanical and thermal properties were experimentally investigated. It was found that the use of recycled masonry aggregate led to better thermal properties while maintaining sufficient mechanical properties. On the contrary, the addition of recycled expanded polystyrene did not significantly affect the thermal properties of concrete, but the mechanical properties considerably declined. For this reason, the recycled masonry aggregate is suitable to use as an aggregate for concrete masonry blocks for wall structures.

scholarly journals Mechanical Properties of Geopolymer Concrete Made With Partial Replacement of Coarse Aggregate by Recycled Aggregate

2019 ◽  
Vol 9 (1) ◽  
pp. 2301-2304 ◽  
Keyword(s):  
Mechanical Properties ◽  
Sodium Hydroxide ◽  
Sodium Silicate ◽  
Coarse Aggregate ◽  
Recycled Aggregate ◽  
Recycled Aggregates ◽  
Partial Replacement ◽  
Geopolymer Concrete ◽  
Recycled Coarse Aggregate ◽  
Coarse Aggregates

Construction is the one the fast growing field in the worldwide. There are many environmental issues connected with the manufacture of OPC, at the same time availability of natural coarse aggregate is getting reduced. Geopolymer binder and recycled aggregates are promising alternatives for OPC and natural coarse aggregates. It is produced by the chemical action of inorganic molecules and made up of Fly Ash, GGBS, fine aggregate, coarse aggregate and an alkaline solution of sodium hydroxide and sodium silicate. 10 M sodium hydroxide and sodium silicate alkali activators are used to synthesis the geopolymer in this study. Recycled aggregates are obtained from the construction demolished waste. The main focus of this work is to find out the mechanical properties of geopolymer concrete of grade G40 when natural coarse aggregate(NCA) is replaced by recycled coarse aggregate in various proportions such as 0%, 10%, 20%, 30%,40% and 50% and also to compare the results of geopolymer concrete made with recycled coarse aggregates(RAGPC) with geopolymer concrete of natural coarse aggregate(GPC) and controlled concrete manufactured with recycled aggregates(RAC) and controlled concrete of natural coarse aggregates(CC) of respective grade. It has been observed that the mechanical properties are enhanced in geopolymer concrete, both in natural coarse aggregate and recycled coarse aggregate up to 30% replacement when it is compared with the same grade of controlled concrete.

Review on Different Types of Geopolymer Concrete Fibres

2016 ◽  
Vol 857 ◽  
pp. 388-394 ◽  
Author(s):  
Meor Ahmad Faris ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
Khairul Nizar Ismail ◽  
Ratnasamy Muniandy ◽  
Aeslina Abdul Kadir ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Ordinary Portland Cement ◽  
Geopolymer Concrete ◽  
Base Materials ◽  
Different Types ◽  
History Of ◽  
Binder Material ◽  
Materials Used

Ordinary Portland Cement (OPC) has been used over the than hundred years for material construction especially as a binder in production of concrete. However, there are a few disadvantages with the using of OPC that have been found especially in terms of properties and green house effect. This paper reviews the potential of an alternative binder material with no cement usage (cementless) called as “geopolymer”. The history of the development geopolymer will be described. Different types of base materials used in the formation of geopolymer will be explained in details. The influence of different types of fibres to the mechanical properties especially compressive strength and flexural strength were explained well.

Creep Property of Concretes with Different Types of Coarse Aggregates

2012 ◽  
Vol 174-177 ◽  
pp. 308-313 ◽  
Author(s):  
Yan Jun Liu ◽  
Mang Tia
Keyword(s):  
Prestressed Concrete ◽  
Prediction Models ◽  
Creep Property ◽  
Cementitious Materials ◽  
Prestress Loss ◽  
University Of Florida ◽  
Coarse Aggregates ◽  
Concrete Mixtures ◽  
Florida Department ◽  
Different Types

The rheological phenomenon of concrete materials, also termed as creep, is one of very important properties of concrete. Excessive deformation caused by creep does more detrimental effects on prestressed concrete structures than otherwise. Even though some investigations had been conducted on the normal concrete mixtures by the researchers and engineers all over the world, and the conclusions and the creep prediction models based on those investigations were developed, their effectiveness to be extended to all the concrete mixtures is very limited due primarily to the susceptibility of the creep property of concrete to the variation of the properties of aggregate, cement, water to cementitious materials ratio and their proportions. Especially for prestress concrete, creep induced prestress loss puts severe threat on the safety and durability of prestressed structures. Thus, in order to thoroughly understand the creep characteristics of the typical concrete mixtures used in Florida, this project was carried out by University of Florida and Florida Department of Transportation. The investigation found out that the creep strains of the concretes with different types of coarse aggregates at 91 days are very close, while the differences of creep coefficients of the concretes with different aggregates are fairly significant.

scholarly journals Refractory and Mechanical Properties of Dealuminated Kaoline-Based Geopolymer Concrete

2020 ◽  
Vol 8 (5) ◽  
pp. 2045-2049
Keyword(s):  
Mechanical Properties ◽  
Refractory Concrete ◽  
Geopolymer Concrete ◽  
Thermal And Mechanical Properties ◽  
Concrete Mixtures ◽  
Cold Crushing Strength ◽  
Aluminous Cement ◽  
Shock Resistance ◽  
Alkaline Activator ◽  
Geopolymer Paste

This study has been performed to evaluate the performance of the industrial by-product dealuminated kaolin (DK) as geopolymer paste in production a refractory concrete. The paper study the thermal and mechanical properties of concrete mixtures containing crushed refractory brick as combined aggregate and geopolymer paste produced from the blend of 10%, 20% and 30% of DK, ordinary Portland cement (OPC), solution of sodium hydroxide and sodium silicate as alkaline activator. These concrete mixtures were tested for workability, shrinkage at 400,800 and 1200 °C, thermal shock resistance at temperature of 950 °C, Cold crushing strength, tensile strength, and elastic modulus. The results of these mixtures compared with the results of concrete mixtures containing 100% OPC and 100% aluminous cement (AC) .The results show that the thermal and mechanical properties of geopolymer concrete produced by dealuminated kaolin (DK) are enhanced. Also, it is found that mixture contains 20% of DK appears to be the optimal geopolymer concrete mixture.

The Relationship between Mechanical Properties and Shrinkage of the Concretes Used in Florida

2012 ◽  
Vol 204-208 ◽  
pp. 3799-3804
Author(s):  
Yan Jun Liu ◽  
Mang Tia
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Elastic Modulus ◽  
Empirical Relationship ◽  
Lightweight Aggregate ◽  
Shrinkage Strain ◽  
Coarse Aggregates ◽  
Concrete Mixtures ◽  
The Relationship ◽  
Mineral Additives

This paper investigated the mechanical strength and shrinkage properties of the concrete mixtures frequently used in Florida. The concrete mixtures were proportioned with three different types of coarse aggregates, such as Miami Oolite limestone, Georgia granite and Stalite lightweight aggregate, and two mineral additives, including fly ash and slag. And fourteen concrete mixtures were evaluated on their characteristics of compressive strength, elastic modulus and shrinkage for 91 days. The empirical relationship between the mechanical properties of concretes and shrinkage strain was analyzed mathematically. The results indicate that the compressive strength and elastic modulus of concrete are exponentially related the shrinkage strain of concrete. The finding from this study is agreeable with that by Troxell et al [5]. Also, the effectiveness of ACI 209 and CEB-FIP models on predicting the shrinkage behavior of concretes used frequently in Florida was evaluated. The result indicates that CEB-FIP model gives more reliable prediction than ACI 209 model does.

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