scholarly journals The Beneficial Effect of the Addition of Fly Ash on Reduction of the Size of Microcracks in the ITZ of Concrete Composites under Dynamic Loading

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 668
Author(s):  
Grzegorz Ludwik Golewski
Keyword(s):  
Fly Ash ◽  
Beneficial Effect ◽  
Dynamic Loading ◽  
Coarse Aggregate ◽  
Interfacial Transition Zone ◽  
Dynamic Loads ◽  
Cement Matrix ◽  
Test Results ◽  
Average Width ◽  
Average Value

The paper presents results of tests on the effect of the addition of fly ash (FA) in the amounts of 0%, 20%, and 30% by weight of cement on the interfacial microcracks in concrete composites subjected to dynamic loads. The analyses were carried out based on the results of the microstructural tests using a scanning electron microscope (SEM). The average width of the microcracks (Wc) in the interfacial transition zone (ITZ) of coarse aggregate with cement matrix was evaluated. During the studies beneficial effect of the addition of FA on reduction of the size of Wc in the ITZ of concrete composites under dynamic loading were observed. Based on obtained test results, it was found that using the 20% FA additive causes favorable changes in the microstructure of mature concrete. In this composite, the average value of Wc was lower by more than 40% compared to the result obtained for the reference concrete. In contrast, concrete containing 30% FA additive had greater microcracks in the ITZ area by over 60% compared to the material without additive. In all analyzed composites, an increase in the Wc value by almost 70% to over 110% in the case of occurrence of dynamic loads was also observed. This was the most evident in the case of concrete with a higher content of FA.

scholarly journals A Preliminary Study on the Physical Properties of an Alternative Coarse Aggregate Made with Red Soil and Fly Ash

2018 ◽  
Vol 12 (1) ◽  
pp. 1-8
Author(s):  
J. Bright Brabin Winsley ◽  
M. Muthukannan
Keyword(s):  
Fly Ash ◽  
Specific Gravity ◽  
Room Temperature ◽  
Coarse Aggregate ◽  
Environmental Issues ◽  
Red Soil ◽  
Test Results ◽  
Ordinary Concrete ◽  
Preliminary Study ◽  
Natural Aggregates

Background and Objective: The demand for course aggregate is increasing every day. Natural aggregate used for ordinary concrete is obtained by quarrying, which cause serious environmental issues. An alternate course aggregate is needed for sustainable development. The objective of this research is to produce an alternative course aggregate in combination with soil available locally near site along with fly ash, to test its properties to make it fit for concrete. Method: An alternative coarse aggregate is produced from red soil and fly ash mixed at various ratios, 100:0, 90:10, 80:20, 70:30, 60:40, 50:50, fresh aggregate granules of different sizes less than 10mm is prepared using hand press, the aggregates were sundried in shade for 24hours, oven dried at 110°C, burned in Muffle furnace at temperature of 950°C and cooled gradually to reach room temperature. After the production, the specific gravity, bulk density, water absorption, Impact and aggregate crushing of the aggregates were tested. Result: Test results showed that aggregates produced are of lesser specific gravity, density with relatively appreciable impact value and crushing value. Conclusion: The test results show that the aggregates produced can be used in construction as replacement for natural aggregates.

Study on the Influence of Mix Design Parameters on the Properties of Self-Compacting Concrete

2013 ◽  
Vol 857 ◽  
pp. 10-19
Author(s):  
Ji Liang Wang ◽  
Xiang Qian Wen ◽  
Jun Hong Shan ◽  
Ying Liu
Keyword(s):  
Fly Ash ◽  
Volume Content ◽  
Coarse Aggregate ◽  
Mineral Admixture ◽  
Design Parameters ◽  
Fine Aggregate ◽  
Test Results ◽  
Self Compacting Concrete ◽  
Volume Stability ◽  
Dry Shrinkage

the influence of mixing amount of mineral admixture, volume content of fine and coarse aggregate have been systematical studied on the workability, mechanical properties and volume stability of self-compacting concrete. Test results showed that with the fly ash content increased, the workability of self-compacting concrete improved significantly, early compressive strength decreased, but increase rate of later strength improved remarkably, and the mixing amount of fly ash inhibited significantly the dry shrinkage of self-compacting concrete; with the volume content of coarse aggregate increased, the workability of self-compacting concrete decreased significantly, but the volume stability of self-compacting concrete improved obviously, thus the optimum volume content of coarse aggregate of self-compacting concrete was range from 0.30 to 0.34; when the volume content of fine aggregate varied at the range of 0.40~0.50, there may be little effects on the workability of self-compacting concrete, but the increase self-compacting concretes volume content could reduce obviously the dry shrinkage of self-compacting concrete. Moreover, the variation in the volume content of coarse and fine aggregate should have slight influence on the early strength of self-compacting concrete, and the influence of the volume content variety on the later strength of self-compacting concrete could be neglected eventually.

The Effects of Na2SiO3/NaOH Ratios on the Volumetric Properties of Fly Ash Geopolymer Artificial Aggregates

2019 ◽  
Vol 967 ◽  
pp. 228-235
Author(s):  
I Dewa Made Alit Karyawan ◽  
Januarti Jaya Ekaputri ◽  
Iswandaru Widyatmoko ◽  
Ervina Ariatedja
Keyword(s):  
Electron Microscope ◽  
Fly Ash ◽  
Scanning Electron Microscope ◽  
Specific Gravity ◽  
Water Absorption ◽  
Asphalt Mixture ◽  
Interfacial Transition Zone ◽  
Volumetric Properties ◽  
Test Results ◽  
Scanning Electron

This study was conducted as a part of a research to assess the influence of the volumetric properties of geopolymer artificial aggregates made of fly ash to the performance of asphalt mixture to be used in pavement layers. This paper presents the parameters adopted during the production of geopolymer artificial aggregates which may affect the volumetric properties and the structure of the aggregates. The investigated volumetric properties included specific gravity and water absorption. In the experiment laboratory, two variables were utilized for producing the artificial aggregates, which might affect the considered volumetric properties. Those variables are pan-granulator slopes and alkaline ratios (the ratios of Sodium Silicate to Sodium Hydroxide). The pan-granulator slopes were set at 3 different angles, i.e. 45o, 50o, and 55o. The selected alkaline ratios were 1.5, 2.0, 2.5, and 3.0. The test results indicated that the best volumetric properties were obtained at a slope of 50o and alkaline ratio of 2.5. The bulk specific gravity values at the best volumetric properties were found to be: 1) oven dry at 1.9 grams/cm3; 2) saturated surface dry (SSD) at 2.0 grams/cm3, and 3) apparent at 2.1 grams/cm3 with 6% water absorption. In addition, the interfacial transition zone and microstructure aggregates were examined by using Scanning Electron Microscope (SEM). In this study, it was found that there were effects of Na2SiO3/ NaOH ratios and the granulation method on the volumetric properties.

Influence of Aggregates on Cracking Sensitivity of Concrete

2012 ◽  
Vol 204-208 ◽  
pp. 3299-3302 ◽  
Author(s):  
Xia Chen ◽  
Jian Jun Yan ◽  
Hua Quan Yang
Keyword(s):  
Compressive Strength ◽  
Stress Test ◽  
Interfacial Transition Zone ◽  
Cement Matrix ◽  
Test Machine ◽  
Test Results ◽  
Concrete Cracking ◽  
Natural Aggregate ◽  
Compressive Strength Of Concrete ◽  
Cracking Sensitivity

Concrete cracking sensitivity made from different aggregates was compared with employment of advanced temperature and stress test machine by tracking thermal and stress development of concrete with age and elements distribution in interfacial transition zone of each concrete was explored by SEM and EDS. Test results indicated that compressive strength of concrete made from basalt and limestone was greater than diorite and natural aggregate and crack resistance of concrete based on cracking sensitivity comparison in terms of cracking temperature varying from minus 0.3°C to minus 2.5°C as diorite, basalt, limestone and natural aggregate. Elements Ca and Mg were apparently accumulated in vicinity of ITZ and some reaction between limestone and cement matrix might have taken place which blurred the boundary between aggregates and cement matrix.

scholarly journals Usefulness of porphyry and amphibolites as a component of concrete for airfield pavements

2018 ◽  
Vol 163 ◽  
pp. 07002
Author(s):  
Małgorzata Linek ◽  
Piotr Nita ◽  
Paweł Wolka ◽  
Wojciech Żebrowski
Keyword(s):  
Bulk Density ◽  
Internal Structure ◽  
Coarse Aggregate ◽  
Cement Matrix ◽  
Physical Parameters ◽  
Hardened Concrete ◽  
Test Results ◽  
Laboratory Test Results ◽  
The Matrix

Coarse aggregate used as part of cement concrete is of primary significance for the obtained parameters of hardened concrete. In case of concretes intended for airfield pavements, the application of granite grit is recommended. Alternative to this type of aggregate in the form of porphyry and amphibolites aggregate was suggested. In order to assess the suitability of different aggregate types for concrete mixes, their bulk density, absorbability, polishing resistance, abrasion and crushing resistance were determined. Also, the internal structure of the suggested aggregates and its influence on changes of hardened concrete composite structure were subject to the assessment. The influence of aggregate type on the structure of cement matrix and contact areas between the matrix and aggregate grains were specified. The observed changes, in case of the internal structure of concretes based on porphyry and amphibolites aggregates, with reference to granite aggregate, resulted in changes of mechanical and physical parameters. Analyses included the determination of bulk density, absorbability, compression, bending and splitting resistance. According to the obtained laboratory test results, the significant influence of the aggregate type applied to the mix on parameters of hardened concrete, with regard to the application thereof to the airfield pavements was proved.

Impacts of Gradation on the Property of Lime-Fly Ash Bound Macadam

2012 ◽  
Vol 178-181 ◽  
pp. 1321-1324 ◽  
Author(s):  
Wen Xue ◽  
Xiang Ping Han ◽  
Zhi Guo Xia ◽  
Qi Zheng
Keyword(s):  
Fly Ash ◽  
Construction Projects ◽  
Coarse Aggregate ◽  
High Strength ◽  
Pavement Performance ◽  
Good Effect ◽  
Test Results ◽  
Aggregate Content ◽  
Fine Aggregates ◽  
Skeleton Structure

This paper studied the lime-fly ash bound macadam mixed with different proportions of lime fly-ash and aggregates which is often used in construction projects, analyzed the impacts of the aggregate content to the unconfined compressive strength, modulus of compressive resilience property with various lime content and is showed that dense skeleton lime-fly ash bound macadam reached the desirable strength property and had good effect on pavement performance Therefore, it is concluded that lime-fly ash bound macadam with desirable property, replacing fine aggregates is achievable, Test results show that coarse aggregate of lime fly-ash stabilized aggregate can form skeleton structure and has the advantage of high strength and other better material properties which can meet the requirements pavement.

An Investigation on the Behaviour of Concrete with Waste Tyre Rubber Fibres as a Partial Replacement of Coarse Aggregate

2011 ◽  
Vol 367 ◽  
pp. 49-54 ◽  
Author(s):  
G. Senthil Kumaran ◽  
M. Lakshmipathy ◽  
Nurdin Mushule
Keyword(s):  
Strain Energy ◽  
Coarse Aggregate ◽  
Tensile Tests ◽  
Partial Replacement ◽  
Cement Matrix ◽  
Human Society ◽  
Test Results ◽  
Rubber Content ◽  
Split Tensile Strength ◽  
Waste Tyres

Concrete is an excellent structural material and considered as essential for the modern civilization and human society. Now, use of waste tyres in concrete has become technically feasible and the concrete is being considered as light weight concrete. The composites were formed with 0%, 5%, 10%, 15%, 20% and 25% of fibers replaced by coarse aggregate weight. The fibers were of different lengths (L) such as 25mm, 50mm and 75mm had holes of diameters (D) 4mm, 5mm and 6mm. The holes functioned as anchors in the cement matrix so that the tyre fibres shall not be separated while placing in the mould. The 3rd, 7th and 28th day’s compression strength and crack patterns were observed on cubes. Split tensile strength on 14th and 28th day were tested on cylindrical specimens. Test results have shown that the increase in rubber content decreases the compressive strength, but, increases the strain energy while conducting the split tensile tests. The composite with fiber specimen L50-D5 and L50-D6 with 10% replacement of coarse aggregate had shown better results than other specimens. However, further studies are needed to reveal the hidden properties of tyre fiber modified concrete.

scholarly journals PENAMBAHAN FLY ASH DAN SERAT SERABUT KELAPA SEBAGAI BAHAN PEMBUATAN BETON

UKaRsT ◽  
2019 ◽  
Vol 3 (1) ◽  
pp. 48
Author(s):  
Eko Siswanto
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Coarse Aggregate ◽  
Absorption Test ◽  
Coconut Fiber ◽  
Average Value ◽  
Variation Data ◽  
Compressive Strength Of Concrete ◽  
Average Compressive Strength

AbstrakAlong with the development of technology today many types of materials and mixtures are used. This study used concrete K-225 jobmix and carried out the addition of coconut fiber as an addition to coarse aggregate and Fly ash as cement enhancer.Jobmix variations of concrete are 0%, 10%, 20%, 30%, and 40%. The number of test specimens from each variation was made 3 pieces of specimens in the form of cubes 15 x 15 x 15 cm, testing the specimens was carried out at the age of 28 days. By testing compressive strength and absorption.                The results showed that the average compressive strength of concrete in each variation was 0% (2800 kg / cm2), 10% (2520 kg / cm2), 20% (2016 kg / cm2), 30% (1411 kg / cm2) and 40% (846 kg / cm2). From the average - compressive strength of concrete in each variation data obtained that the value of compressive strength of concrete with a variation of 10% is equal to the average value of compressive strength K-225. The optimum percentage of coconut fiber fibers in the compressive strength of concrete at a variation of 10% with the conversion results of 260 kg / cm3 reaching k-225 quality. Absorption test with addition of coconut fiber fibers and Fly ash in each variation with an average of ¼ hour (0.101 ml), 1 hour (0.046 ml), 4 hours (0.016 ml), and 24 hours (0.037 ml)  Keywords: Compressive Strength, Absorption, Coconut Fiber, Fly ash.

Research on Pavement Performance of Dense Skeleton Lime Fly-Ash Stabilized Aggregate in Gravelly Conditions

2011 ◽  
Vol 287-290 ◽  
pp. 1033-1036
Author(s):  
Jian Ning Guo ◽  
Shi Bin Ma ◽  
Lei Wang
Keyword(s):  
Fly Ash ◽  
Service Life ◽  
Material Properties ◽  
Coarse Aggregate ◽  
High Strength ◽  
Pavement Performance ◽  
Rigid Base ◽  
Test Results ◽  
Base Course ◽  
Skeleton Structure

Lime fly-ash stabilized aggregate is the commonly material used as semi-rigid base course of pavement and the performance of pavement directly affects its service life. This paper focuses on pavement performance of dense skeleton lime fly-ash stabilized aggregate in gravelly conditions. Test results show that coarse aggregate of lime fly-ash stabilized aggregate can form skeleton structure and has the advantage of high strength and other better material properties which can meet the requirements pavement.

Nanomechanical Performance of Interfacial Transition Zone in Fiber Reinforced Cement Matrix

2018 ◽  
Vol 760 ◽  
pp. 251-256 ◽  
Author(s):  
Vojtěch Zacharda ◽  
Petr Štemberk ◽  
Jiří Němeček
Keyword(s):  
Elastic Modulus ◽  
Transition Zone ◽  
Cement Paste ◽  
Steel Fiber ◽  
Mechanical Performance ◽  
Creep Compliance ◽  
Interfacial Transition Zone ◽  
Cement Matrix ◽  
Average Value ◽  
Reinforced Cement

This paper shows a micromechanical study of interfacial transition zone (ITZ) around steel fiber in cement paste. It investigates microstructure and mechanical performance of the ITZ by a combination of nanoindentation and scanning electron microscopy (SEM). The investigated specimens were made from cement CEM I 42.5R paste with dispersed reinforcement in the form of steel fiber TriTreg 50 mm. The SEM demonstrated larger porosity and smaller portion of clinkers in the ITZ. Nanoindentation delivered values of elastic modulus, hardness and creep parameters around the fiber. An average value of elastic modulus in ITZ was at the level of 67% in comparison with cement bulk and the width of ITZ was about 40 µm. The value of hardness was found to be 60% of the average hardness of the bulk cement paste. The measured load-displacement curves were used for calculation of creep indentation parameter (CIT) and the creep compliance function. An average value of the creep compliance in the ITZ was found to be two times higher than in the cement bulk.

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