STUDY ON BEHAVIOUR OF NANO CONCRETE PROJECT REFERENCE NO.: 38S0380

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1 STUDY ON BEHAVIOUR OF NANO CONCRETE PROJECT REFERENCE NO.: 38S0380 COLLEGE : ADICHUNCHANAGIRI INSTITUTE OF TECHNOLOGY BRANCH : DEPARTMENT OF CIVIL ENGINEERING GUIDE : DR.M. RAME GOWDA STUDENTS : MR. SUSHEEL S M MR. NAVEEN M MR. AVINASH H K MR. L BANCHANLANG SHULLET ABSTRACT Concrete is the most commonly used building material for construction and it consumes almost the total cement production in the world. The use of large quantities of cement produces increasing CO 2 emissions, and as a consequence of the greenhouse effect. A method is to reduce the cement content in concrete mixes is the use of silica fines. One of the silica fines with high potential as cement replacement and as concrete additive is nano-silica (ns). This project work aims to present the state of nano silica application in concrete, focusing on the nano silica properties to render it suitable to be applicable in concrete. It includes the nano silica addition effect and their application in concrete. Also an overview of the experimental setup for developing nano concrete. 1. Introduction "Nano technology is the study of the control of matter on an atomic and molecular scale. It deals with the size 100 nanometres or smaller, and involves developing materials or devices within that size". Nano concrete is one of the most active research areas that encompass a number of disciplines including civil engineering and construction materials, currently, the most active research areas dealing with cement and concrete are: understanding of the hydration of cement particles and the use of nano-size ingredients such as titanium oxide, silica, carbon nano-tubes, and nano-sensors. If cement with nanosize particles can be manufactured and processed, it will open up a large number of opportunities in the field of ceramics, high strength composites etc. It will elevate the status of Portland cement to a high tech material in addition to its current status of most widely used construction material. The main objective of this thesis Dept. of Civil Engineering, AIT, Chikkamagaluru Page 1

2 is to outline some of the applications of nanotechnology in concrete and comparing this concrete with the ordinary concrete. A long time used material concrete is for the first time fully replaced by a nano maternal. It is well known physics and chemistry that a well designed and developed nano material produces better and cheaper cost results than traditional materials. Micro silica has been one of the world's most widely used products for concrete for over eighty years. Its properties allowed high compressive strength concretes; water and chemical resistant concretes, and they have been part of many concrete buildings that we see nowadays. Its disadvantage, though, has been its relatively high cost and contamination, which affects the environment and the operator s health. As micro silica, as a powder, is thousand fold thinner than cigarette smoke. Operators must take special precautions to avoid inhaling micro silica and not to acquire silicosis an irreversible hence to overcome all this above ill-effect of micro silica, nanotechnology was introduced in the world of concrete. Nanotechnology is one of the most active research areas which have wide applications in almost all the fields. As concrete is most useful material in construction industry it has been required to improve its quality. Improving concrete properties by addition of nano particles have shown significant improvement than conventional concrete. Why nanotechnology for concrete? Improves the materials bulk properties. Ability to control or manipulate materials at the atomic scale. To obtain thinner final products and faster setting time. Cost effectiveness. Lowered levels of environmental contamination Dept. of Civil Engineering, AIT, Chikkamagaluru Page 2

3 1.1 Nanoparticle A nano particle is a microscopic particle whose size is measured in nanometres (nm). It is defined as a particle with at least one dimension less than 200nm. Nano particles made of semiconducting material (material that is between a conductor and insulator e.g. silicon) may also be labelled quantum dots if they are small enough (typically sub 10nm) such that jumps in energy levels occur. The importance of this is that the same material of different sizes can emit different colors when energized with, for instance, UV light, Carbon Nano tubes are a sub set of nano particles. 1.2 Concrete and Sustainability Concrete is probably unique in construction, it is the only material exclusive to the business and therefore is the beneficiary of a fair proportion of the research and development money from industry. Concrete is a composite construction material composed primarily of aggregate, cement, and water, which is a nanostructure, complex, multi-phase material that ages over time. Sustainability is defined by the World Commission on Environment and Development as the development that meets the needs of the present, without compromising the ability of the future generations to meet their own needs. It is basically an idea for concern for the wellbeing of planet Earth with continued growth and human development. The current construction practices are based on the consumption of enormous quantities of building materials and drinking water, resulting in the scarcity of these resources after a long turn. The sustainable development of the cement mortar would save not only the natural resources and energy but also protect the environment with the reduction of waste material. The mortar properties in fresh state such as workability are governed by the particle size distribution and the properties in hardened state, such as strength and durability, are affected by the mix grading and resulting particle packing. Rheological properties of a fresh cement paste play an important role in determining the workability of concrete. The water requirement for flow, hydration behavior, and properties of the hardened state largely depends upon the degree of dispersion of cement in water. Factors such as water content, early hydration, water reducing admixtures and mineral admixtures like silica fume determine the degree of flocculation in a cement paste. Dept. of Civil Engineering, AIT, Chikkamagaluru Page 3

4 1.3 Nanotechnology in Concrete Nanotechnology is rapidly becoming the Industrial Revolution of 21st century. It will affect almost every aspect of one s life. In comparison to other technologies, nanotechnology is much less well defined and well-structured. It is known that Nano is a Greek word and means dwarf. It does not mean dealing with dwarfs but it became a common word for everything which is smaller than 1 Micron or 1 million of a millimeter. 1 Micron is 1000 Nanometer. The nano science and nano-engineering (nanomodification) of concrete are terms that have come into common usage and describe two main approaches of applications of nanotechnology in concrete Until today, concrete has primarily been seen as a structural material. Nanotechnology is helping to make it a multipurpose smart functional material. Concrete can be nanoengineered by the incorporation of nano-sized building blocks or objects (e.g., nanoparticles, nano admixtures and nanotubes) to control material behavior and add trailblazing properties, or by the grafting of molecules onto the cement particles, cement phases, aggregates, and additives (including nano-sized additives) to provide the surface functionality adjusted to promote the specific interfacial interactions of the molecules. Recently, nanotechnology is being used in many applications and it has received increasing attention also in building materials, with potential advantages and drawbacks being underlined. The scale of various constituents of concrete is shown in Fig 1.3. Fig1.1: Scale of various constituents of concrete 1.4 Silica fume Dept. of Civil Engineering, AIT, Chikkamagaluru Page 4

5 Silica is the common name for materials composed of silicon dioxide (SiO2) and occurs in crystalline and amorphous forms. Silica fume or micro-silica (SF) is a by-product of the smelting process in the silicon and ferrosilicon industry. The American concrete institute defines silica fume as Very fine non crystalline silica produced in electric arc furnaces as a by-product of production of elemental silicon or alloys containing silicon. It is a grey coloured powder, similar to Portland cement or fly ashes. It is an ultrafine powder collected as a by-product of the silicon and ferrosilicon alloy production and consists of spherical particles with an average particle size (diameter) of 150 nm. The main field of application is as pozzolanic material for high performance concrete. 1.5 Nano-silica Fig 1.2: Silica fume Nano silica is typically a highly effective pozzolanic material. It normally consists of very fine vitreous particles approximately 1000 times smaller than the average cement particles. It has proven to be an excellent admixture for cement to improve strength and durability and decrease permeability Nano Silica reduces the setting time and increases the strength (compressive, tensile) of resulting cement in relation with other silica components that were tested Nano-silica is obtained by direct synthesis of silica sol or by crystallization of Nano-sized crystals of quartz. Fig 1.3: Nano silica Dept. of Civil Engineering, AIT, Chikkamagaluru Page 5

6 2. Objectives of the Present Investigation The following objectives are derived on the basis of literature review, 1. Developing Nano silica concrete and study of fresh and hardened properties of developed concrete in the laboratory. 2. Comparative analysis of compressive and split tensile strength of conventional concrete and concrete developed with nano silica Material. 3. Methodology 3.1 General The Methodology consists of three phases; First phase covers the design of mixes by using suitable mix design method as per the literature review. The second phase covers the achievement of desired design mix by doing trial and error procedure by satisfying all the rheological characteristics. The third phase covers the study of hardened properties of developed mixes in the laboratory. 3.2 Methodology Details The present investigation is to design M 60 grade High strength concrete. Further developed mixes are studied both for rheology as well as hardened properties. In this study cement is replaced by silica fume and Nano silica material. Further it is planned to chalk out the program for casting number of cubes and cylinders. The mix design planned is American Concrete Institute method, because it is flexible when compared to other methods of mix design. The percentage replacement of nano silica is chosen in the range from 0-4% at an interval of 1.0%. 3.3 Experimental programme: The experimental procedure consists of testing the basic materials in the laboratory. The design mix is worked out by American concrete institute method using basic material test results, and then the developed ratio is taken as a mix ratio. The mix design is shown in Appendix II. For this mix ratio cement is replaced by Nano silica (0-4%) at an interval of 1.0% in an increasing order. All mixes developed are studied and tested for both fresh and hardened properties. Total 90 specimens were casted and tested for compressive and split tensile strength in the laboratory. The details of specimen proposed to be cast is as shown in table 3.1. Table 3.1 : Details of cubes and cylinder with various percentages of Nano silica Dept. of Civil Engineering, AIT, Chikkamagaluru Page 6

7 Mixes Silica Fume replacement (%) Nano silica as additive (%) Cubes Cylinders 7 days 28 days 56days 7days 28days 56days Control mix Samples Conclusions And Scope For Future Work Conclusions The conclusions are on the basis of experimental investigation in the laboratory It can be stated that adequate quantities of super plasticizers are to be added when admixtures like nano silica and condensed silica fume (CSF) are used along with cement in high strength concrete mixes. 3.0% of nano silica appears to be the optimum in the high strength concrete mixes like M 60. The highest compressive strength with 3.0% of nano silica and and 5% of CSF appears to be optimum in the present blended concrete mixes. In the case of split tensile strength 2% of nano silica gives the highest value. The highest strength with 2% of nano silica and 5% CSF appears to be the optimum in present condition for split tensile strength. In the present project work, the mineral admixture CSF is much finer than cement and as such its water demand is also more. Hence, when both nano silica and CSF are used in high strength concrete mixes, the workability is getting very adversely affected. With the introduction of nano materials like nano silica in concrete it is expected that better composites of concrete can be prepared to answer any kind of situation faced by the structures. Scope for Future Work The same work is extended to study the flexural properties of developed Nano silica concrete by using Nano silica materials. Dept. of Civil Engineering, AIT, Chikkamagaluru Page 7