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  3. Laboratory investigation of mechanical properties and shrinkage of lightweight concrete containing nano-silica particles

Laboratory investigation of mechanical properties and shrinkage of lightweight concrete containing nano-silica particles

Number of pages: 129 File Format: word File Code: 31386
Year: 2011 University Degree: Master's degree Category: Civil Engineering
Tags/Keywords: Concrete shrinkage - Light concrete - Lightweight aerated concrete - Lightweight concrete containing nano-silica particles - Lightweight concrete with high strength - Lightweight concrete with nano-silica particles - Mechanical properties - Mechanical properties of lightweight concrete - Nanosilica particles
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  • Summary of Laboratory investigation of mechanical properties and shrinkage of lightweight concrete containing nano-silica particles

    Dissertation for Master's Degree

    Civil-Structural Field

    Abstract:

    One of the important problems in seismic design and implementation of buildings is the significant dead weight used in it. Therefore, in case of using lightweight concrete that has favorable mechanical properties, significant advantages can be obtained, including a reduction in dead load and earthquake force, which will ultimately lead to the economicization of the project. Considering that lightweight concrete has less resistance due to the low specific weight of this type of concrete, researchers have always tried to improve its mechanical properties by using additives to lightweight concrete.                                                                                      

    In this laboratory research, the effect of nanosilica and microsilica pozzolans on the mechanical properties of lightweight concrete has been tested, including compressive strength, tensile strength, as well as ultrasonic testing to determine the dynamic elasticity modulus and shrinkage test. In examining the effect of mixing nano-silica with micro-silica, the highest compressive strength was obtained for 2% of nano-silica and 7.5% of micro-silica. The use of nano silica up to 4% reduces the strain caused by shrinkage and improves the dynamic modulus of elasticity. Also, mixing 2% of nanosilica with 7.5% of microsilica reduces the strain. But the mixing of nano silica with percentages higher than 7.5 percent of micro silica reduces the aforementioned mechanical properties. Keywords: nano silica, micro silica, lightweight concrete, Lika, properties Chapter 1: Introduction and General 1-1. Introduction

    One of the important problems in the seismic design and execution of buildings, especially tall buildings and large concrete bridges, is the significant dead weight used in it. Therefore, in the case of using lightweight concrete that has favorable mechanical properties, significant advantages can be obtained, including a reduction in dead load and earthquake force, and as a result, a reduction in cross-sections in beams, columns, slabs, and foundations, as well as better performance in terms of thermal insulation and favorable fire resistance, which will ultimately lead to the economicization of the design. However, due to the fact that the mechanical properties of concrete often have a direct relationship with its specific weight, light concrete has less resistance due to the low specific weight of this type of concrete. Therefore, researchers have always tried to improve the mechanical properties of lightweight concrete by using additives.                                                                                       

    With the advancement of technology and mankind's access to nanotechnology due to the special capabilities it offers to humans, the need to use it in the concrete industry is strongly felt. The reason for paying attention to nanotechnology is that by reducing the size of particles, new and unusual mechanical, electrical, magnetic and It can be seen that it is not possible to achieve these features in normal mode.  

    1-2. Stylization

    Stylation is one of the new topics in construction science, which is expanding and progressing day by day. This technology consists of reducing the finished weight of the building by using new techniques of making new materials and optimizing execution methods. Reducing the weight of the building, in addition to saving the cost of time and energy, reduces the losses caused by natural disasters such as earthquakes and minimizes the damage caused by the heavy weight of the building [1]. Stylization and strengthening of buildings against earthquakes is considered essential, and in this regard, upgrading the scientific and specialized level in the country's engineering community and familiarizing with new building systems and materials is inevitable. On the other hand, solving problems such as long implementation time or the high cost of building construction in the housing sector requires providing solutions to expand the use of new methods and new construction materials to reduce weight, reduce construction time, and ultimately reduce the cost of implementation. This, in turn, will optimize the construction, increase the production of housing in the country and achieve more favorable conditions in the implementation.The necessity of lightening is explained according to the reduction of the force on the building against the earthquake, one of the methods of reducing the force on the building in an earthquake and the basic shear force is to reduce the weight of the structure based on most existing regulations, including the 2800 earthquake standard. Considering that Iran is an earthquake-prone country, the construction of residential places with light materials should be accepted as a principle.

    1-3. Light concrete

    1-3-1. The definition of lightweight concrete according to the definition of the American Concrete Institute ACI 116R-87 is: "Concrete whose specific weight is significantly lower than the specific weight of concrete made with natural or broken aggregates". 1-3-2. Lightweight concrete manufacturing methods

    Lightweight concrete is made in 3 different ways:

    1- By removing fine grains from concrete granulation, concrete is obtained which is called "concrete without fine grains".  

    3- By creating air bubbles inside the cement slurry, when it is taken, a sponge-like material is called "gas concrete"[2].

    1-3-3. Properties of light concrete

    This concrete works in such a way that it becomes moisture-proof and does not act like ordinary concrete that absorbs water and repels water. This concrete is made under direct pressure (press). Due to the formation of concrete under pressure, its structure has an acceptable integrity. Lightweight concrete is poured in molds designed by experts. Due to the integrity of the concrete building type, the manufactured piece will have high strength and will show high resistance against earthquakes. To strengthen this concrete, one or more layers of metal mesh are used inside the concrete, which is similar to reinforcing ordinary concrete with rebar. The production cost of this type of concrete is lower than other building materials in proportion to its characteristics. Much less time is needed to produce lightweight concrete walls or other parts. The waste of raw materials for the production of lightweight concrete is much less than normal concrete, because all the production steps are carried out in a specific place and are designed for the production process [3].

    1-3-4. Advantages of lightweight concrete The advantages of using lightweight concrete are:

    Reducing the weight of the structure due to its low weight "about 300 to 1750 kg per cubic meter" compared to ordinary concrete with a specific weight of 2400 kg/m3

    2- Reducing the dimensions of structural elements such as beams, columns and foundations and the possibility of using smaller sections

    3- Reducing the earthquake force on the structure

    4- Reducing the load on concrete forms due to the reduction of the dimensions and light weight of light concrete

    5- Advantage of the speed rating in installation and compliance with any type of construction plan

    6- High resistance due to the use of additives

    7- Light concrete is considered to be a better insulator than normal concrete in terms of heat transfer and sound[4].

    1-3-5. Disadvantages of buildings made with light concrete

    Buildings have special problems that can be briefly mentioned in the following examples:

    Problems of connecting structural members together

    Transportation problems

    Problems of sealing joints

    Need for an expert installation group

    Specialized maintenance

    Problems of installing non-standard components A structure to the walls

     

    1-3-6. The problems of light concrete mixing plan and ways to deal with it

    With the increase in demand for light concrete consumption, attention to the problems of its mixing plan, pouring, compacting and processing was also raised and an attempt was made to provide a solution for it. One of the problems is controlling the efficiency and thus controlling the ratio of water to cement in lightweight concrete. It is recommended to use light grains in two states, completely dry or completely pre-moistened. If the water absorption of light grains is too high, a pre-moistening method is used for these concretes so as not to witness a sharp drop in slump. Pre-moistening means increasing the moisture and water absorbed by the plant. If the light water absorption is low, there is no need for pre-moistening. The problem of separation in the place and pouring of light concrete is serious, so it is recommended that the concrete slump (except for pumped concrete) does not exceed 10 cm, and its appropriate value is 5 to 7.5 cm.

  • Contents & References of Laboratory investigation of mechanical properties and shrinkage of lightweight concrete containing nano-silica particles

    List:

    Chapter One: Introduction and Generalities

    1-1. Introduction. 2

    1-2. stylization 2

    1-3. Light concrete. 3

    1-3-1. definition 3

    1-3-2. Methods of making lightweight concrete. 3

    1-3-3. Characteristics of lightweight concrete. 4

    1-3-4. Advantages of lightweight concrete. 4

    1-3-5. Disadvantages of buildings made with lightweight concrete. 5

    1-3-6. Problems of lightweight concrete mixing plan and ways to deal with it. 5

    1-4. Research background. 6

    1-5. The purpose of the research. 9

    Chapter Two: Knowing the types of lightweight concrete additives and nano materials

    2-1. Introduction. 12

    2-2. Classification of lightweight concrete. 12

    2-3. Properties of lightweight concrete. 16

    2-4. Methods of increasing the strength of lightweight concrete. 17

    2-5. Types of light grains 17

    2-6.  Natural light grains. 18

    2-6-1. pumice stone 18

    2-6-2. mineral pumice 18

    2-6-2-1. Uses of mineral pumice. 18

    2- 7. Synthetic light seeds produced domestically. 19

    2-7-1. pearlite 19

    2-7-1-1. How to prepare perlite. 19

    2-7-1-2. Application of perlite. 20

    2-7-1-3. Sources of perlite in the country and the world. 21

    2-7-2.  Leica 21

    2-7-2-1. Advantages and applications of Leica in the construction industry. 22

    2-8. Types of light concrete. 27

    2-8-1.  Beton Lika 27

    2-8-2.  Gas light concrete. 27

    2-8-3.  Polystyrene concrete. 28

    2-8-3-1.  The advantages of polystyrene light concrete are: 28

    2-8-3-2.  Disadvantages of polystyrene light concrete. 29

    2-9.  High strength concrete. 29

    2-9-1.  Advantages of using high strength concrete. 30

    2-9-2.  Disadvantages of using high strength concrete. 31

    2-9-3. High strength concrete mixing design. 31

    2-10. Economic aspects of lightweight concrete. 34

    2-11. Pozzolans 35

    2-11-1. Definition of pozzolans 35

    2-11-2. Motivation to use pozzolans 35

    2-11-3. The effect of pozzolans on the compressive strength of concrete. 36

    2-11-4. Pozzolanic portland cement. 36

    2-11-5. Microsilica. 37

    2-11-6.  fly ash 38

    2-12. Lubricants and super-lubricants: 39

    2-13. The role of stone powder in improving the properties of lightweight concrete with high strength. 40

    2-14. The effect of the type of lyca granulation on the mechanical properties of lightweight concrete. 40

    2-15. Implementation issues of structural lightweight concrete. 41

    2-16. Nanomaterials and their characteristics 41

    2-16-1. Introduction. 41

    2-16-2. Nanocomposite materials. 42

    2-16-3. Amorphous nano silica. 43

    2-16-3-1. Nanosilica and comparing some of its properties with microsilica 44

    2-16-4. Nanotubes 46

    Chapter three: raw materials and methods

    3-1. Introduction. 49

    3-2. Materials used (Material) 49

    3-2-1. cement 49

    3-2-1-1. Portland pozzolanic cement (PPC) 49

    3-2-2. Mixing water. 50

    3-2-3. Aggregates 50

    3-2-3-1. Los Angeles test on coarse aggregates. 52

    3-2-4. Nanosilica additive. 54

    3-2-5. Microsilica additive. 55

    3-2-6. Super lubricant additive 56

    3-3. Examples and how to process them 57

    3-4. Research method. 57

    3-5. Mixing plan. 58

    Chapter Four: Test Results and Their Discussion

    4-1. Introduction. 61

    4-2. Results of lightweight concrete tests. 61

    4-2-1. Compressive strength test. 62

    4-2-1-1. Compressive strength test for the design of mixtures containing nanosilica (2, 3 and 4) 63

    4-2-1-2. Compressive strength test for the design of mixtures containing microsilica (5 and 6) 67

    4-2-1-3. Compressive strength test for the design of mixes containing nano mix with micro (7 to 12) 69

    4-2-2. Indirect tensile strength test. 72

    4-2-2-1. Indirect tensile strength test for the design of mixtures containing nanosilica (2, 3, and 4) 74

    4-2-2-2. Indirect tensile strength test for the design of mixtures containing microsilica (5 and 6) 76

    4-2-2-3. Indirect tensile strength test for the design of mixtures containing the mixing of nanosilica with microsilica (7 to 12) 78

    4-2-3. Ultrasonic pulse velocity (UPV) test 83

    4-2-3-1. Pulse rate method. 83

    4-2-3-2. Factors affecting pulse rate. 83

    4-2-3-3. Application of the pulse speed method. 84

    4-2-3-4. Ultrasonic testing for designUltrasonic testing for the design of mixtures containing nanosilica (2, 3, and 4) 86

    4-2-3-5. Ultrasonic testing for the design of mixtures containing microsilica (5 and 6) 88

    4-2-3-6. Dynamic elasticity modulus test for the design of mixtures containing mixing of nanosilica with microsilica (7 to 12) 90

    4-2-4. Concrete shrinkage test. 93

    4-2-4-1. Introduction. 93

    4-2-4- 2. Effective factors in shrinkage. 93

    4-2-4-3. Types of concrete shrinkage. 94

    4-2-4-4. The relationship between internal processing and aggregation. 94

    4-2-4-5. Shrinkage test results. 95

    4-2-4-6. Shrinkage test for the design of mixtures containing nanosilica (2, 3 and 4) 96

    4-2-4-7. Shrinkage test for the design of mixtures containing microsilica (5 and 6) 98

    4-2-4-8. Shrinkage test for the design of mixtures containing nano mixing with micro (7 to 12) 100

    Chapter five: conclusions and suggestions

    5-1. Introduction. 105

    5–2. conclusion 105

    5- 3. Suggestions. 107

    Resources and References 108

    Source:

    - Hamed Makhdomi, Reza Rahgozar, April 1389, "Investigation of concrete lightening and its additives - advantages and applications", International Conference on Lightening and Earthquake, Kerman.

    2- Payam Ashtari, Mahdieh Sadat Mirrahimi, April 1389 1389, "Investigation of the proposed mixing plan of structural lightweight concrete with light-grained perlite", International Lightening and Seismic Conference.

    3- Tina Tafarj Fakour, Hamed Ahmadi Moghadam, Mohammad Kamranzadeh Fomeni, May 1389, "Investigation of the mixing plan of lightweight concrete containing microsilica and nanosilica", the third national conference on urban retrofitting and management.

    4- Ramzanianpour, Jahormi, Mahdikhani, Modi, 15 October 2018, "Comparison of the effect of nano-silica and silica fume on mechanical properties, microstructure and durability", Proceedings of the first national concrete conference.

    5- Ali Qods, "Investigation of the effect of steel fibers on the durability of lightweight concrete", 14th Civil Engineering Student Conference.

    6- Malek Mohammad Ranjbar, Rahmat Madandost, Seyed Yasin Mousavi, Ali Sadr Mumtazi, 2018, "Evaluation Durability of lightweight concretes containing expanded polystyrene (EPS) grains in a destructive salty environment", 8th International Civil Engineering Congress.

    7- Agil Ahmadi, Mohammad Reza Sohrabi, 1387, "Investigation of the effect of metakaolin on the mechanical properties and durability of lightweight concrete in aggressive environmental conditions", 4th National Civil Engineering Congress.

    8- Ali Ahmadvand, Isfand 1375, "Laboratory investigation of the use of concrete Lightness in Composite Slabs with Kolahi Profile", Master's Thesis, University of Science and Technology.

    9- Mohammad Reza Yadalhi, Autumn 1380, "Preparation of Lightweight Concrete with High Strength and Its Economic Evaluation", Master's Thesis, University of Science and Technology.

    10- Abdul Naser Rigi, Spring 1383, "Preparation of Lightweight Concrete Using Natural Pumice Granules and Evaluation of Its Properties", Master's Thesis, University of Sistan and Baluchistan.

    11- Abbas Naseri, Shahrivar 2016, "Investigation of the use of lightweight concrete in the construction of segmental maintenance linings of tunnels", master's thesis, University of Tehran.

    12- Morteza Hossein Ali Beigi, Seyyed Baqer Hosseinian, Payam Shafiq, May 2018, Mazandaran University Faculty of Engineering publication article.

    13- Vendidad Company.

    14- Ali Sadr Mumtazi, Akbar Khodaparast Haghi, May 1387, "Investigating the mechanical properties of lightweight fiber concrete containing bulk polystyrene and obtaining the optimal mixing ratio", 4th National Civil Engineering Congress, Tehran.

    15- Hamidreza Irani, Vahid Rahimi, Behrouz Hosni, 1389, "The effect of light weight granularity on the compressive strength of lightweight concrete with high strength". National Conference of Civil Engineering and Sustainable Development.

    16- Aggregate standard, lightweight aggregates used in concrete blocks (Iranian Standard No. 7657).

    17- Marjan Dehghani, Asda. Mahmoodzadeh, 1389, "Using lightweight concrete in the structure of lightening and strengthening housing", International Conference on Lightening and Earthquake.

    18- Arzoo Emdadi, Nicholas Ali Lieber, "Effect of thermal insulation of building walls made with lightweight concrete in reducing fuel consumption and total cost", University of Tehran.

    19- Morteza Hossein Ali Beigi, Seyed Baqer Hosseinian and Payam Shafiq, 1385, "Construction of lightweight concrete with high strength with The use of light grains, stone powder and microsilica", Mazandaran University Faculty of Engineering publication.

    20- Concrete Technology, Navi Del, translated by Ramzanianpour, A.A., Shah Nazari, M.H., 2011, Azarang Publications.

    21- Mohammadi Tehrani, Fariborz, "Leica Comprehensive Guide", Leica Company.

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