International Journal of Engineering Science Invention Research & Development; Vol. II Issue VIII February e-issn:

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1 International Journal of Engineering Science Invention Research & Development; Vol. II Issue VIII February 216 STUDY ON REACTIVITY OF NANO-CEMENT IN CONCRETE R.Selvaraj *1, M.Amirthavarshini *2 *1 Principal Scientist & Head, Civil Material Testing Laboratory, *2 P.G Project student, CSIR-CECRI, Karaikudi, Tamil Nadu- India. *1 *2 Abstract- Many innovative materials and methods are being developed global wide. One of such developments in the building industry is the development of nanotechnology in concrete making. In this research work, three kinds of nano cements are prepared and partially replaced in conventional concrete in three different percentages (1%, 2% and 3% by weight of (OPC) ordinary Portland cement), and keeping all other constituent materials unchanged. All essential characteristic studies are carried out. It is found that 3% replacement of OPC with nano OPC performed in excellent manner in all the characteristic strength measurements, and proved to be an outstanding construction material for many applications in the building industry. Keywords: Nano cement, Pozzolanic activity, compressive strength, Portland cement. I. INTRODUCTION Many developments are taking place in all the branches of engineering. In the building industry, many innovative and sustainable building materials are being developed to satisfy the need of builders and structural engineers. Very often the builders or constructors demand for light weight, quick setting, low-cost, eco-friendly and highly durable materials because such materials will enable builders easy handling, easy transport with reduced cost of construction and with high performance. Nanotechnology and nano-science offer the cement industry a significant opportunity for sustainable development, being ordinary Portland cement (OPC) the most widely used material in the construction industry all over the world. Science Nanotechnology was unofficially introduced by Richard P. Feynman In the past fifty years, plenty of revolutionary developments in all fields of have been reported and particularly last two decades have witnessed a rapid growth in research and development in the field of nanotechnology and nano-science especially nano-structural materials[luna.a.g, November 29]. The term Nanotechnology has becoming progressively popular to our society with a commonmisconception that nanotechnology deals with only small substance overlooking thefact that extraordinary properties of some bulk materials are produced as a result of manipulations at the nanoscale level of the material itself. Nanotechnology in the construction industry, on the other hand, only until recent years, has emerged from fundamental research to industrial applications, mainly because the high potential of this technology offers to improve the properties and performance of cementitious materials. In this paper, study has been made by physical activation of OPC ie making the cement particles to nano size with the keep of high energy milling (by micro pulverizing) and this activated OPC of three different particle sizes was used in the conventional concrete at three different percentages to replace OPC itself partially. A complete characterization study on mechanical properties is carried out. II. EXPERIMENTAL PART A. MATERIALS USED Ordinary Portland cement 43 grade, Dalmia brand, conforming to IS 8112 was used for this study. Very fine sand with fineness modulus being 1.89 was used. The coarse aggregate used was 1 mm and down size. The super plasticizer (high range water reducer) was obtained from M/S CHEMCON tecsys, Chennai; the brand name was CONXL-PCE 665. The super plasticizer is based on poly carboxylate ether polymer. The main polymer chain has been carboxyl groups for the adsorption on the surface of the cement particles and long polyethylene oxide graft chains. This keeps the cement particles physically away from each other. It comprises of R.Selvaraj and M.Amirthavarshini ijesird, Vol. II Issue VIII February 216/488

2 Splitting tensile strength f sp (Mpa) control Cylinder compressive strength f cy (Mpa) control Cube compressive strength f cu (Mpa) International Journal of Engineering Science Invention Research & Development; Vol. II Issue VIII February 216 particles in the range of.25 to.35 micrometers, specific gravity 1.12, ph7, and conforms to ASTM C 494 type B, Type D and Type G and complies with IS The water used for mixing the concrete was potable tap water. No pozzolanic materials such as fly ash, micro silica, silica fume, blast furnace slag are used in this concrete. The nanocement was obtained by pulverizing in a computer controlled high speed, high energy milling device with a rotational speed of 6rpm and ball to powder (B/p) ratio: 1/46[3, 4].There different nano-cement products were milled with18%, 26% and 36% of nano particles being below two micron size and all the above percentages are designated as FC1,FC2 and FC3 respectively and the particle size analyser used for particle size analysis was cilas 118 analyser. B. CHARACTERISATION TEST For characterization study ten concrete mixes were designed including one control mix. The detail of mix design is shown in Table 1. The designation NCC stands for nanocement concrete. Three different nano-cements are used to replace OPC at 1%, 2% and 3% by the weight of OPC itself. Cubes of size 15mm x 15mm x 15mm were cast for determination of cube compressive strength, cylinders of size 15mm diameter and 3mm long were cast for the determination of cylinder strength, the same size of cylinders were used for determining split tensile strength of this material. The flexural strength were obtained from the beam specimen of size 5mm x 5mm x 3mm. Table 2 shows the average characteristic strengths in cube compression, cylinder compression, splitting tensile strength and flexural strength. The trend of variation of various strength of materials is shown from Fig.1 to Fig. 4. Table 3 shows the ratio of strengths keeping the cube strength as the base. The Fig 5 shows the micropulveriser used for milling OPC to nano scale Fig 1. Shows Cube compressive strength of various materials Fig 2. Shows Cylinder compressive strength of various materials Fig 3. Shows splitting tensile strength of various materials R.Selvaraj and M.Amirthavarshini ijesird, Vol. II Issue VIII February 216/489

3 control Flexural strength f r (Mpa) International Journal of Engineering Science Invention Research & Development; Vol. II Issue VIII February 216 III Fig 4. Shows flexural strength of various materials Fig 5. Shows the micropulveriser used for milling RESULTS AND DISCUSSION From Table 1, it can be seen that the control mixture had a water to cement ratio as.44, despite using superplasticizers and the strength after 28 days curing was 29.3 MPa. Whereas the nanocement(opc- replaced) nano concrete, for which same mixture proportion was maintained except only the replacement level of nano OPC and dosage of superplasticizers and has shown a drastic improvement of all strength characteristics after 28 days of curing ie with a minimum of 5.19 MPa for NCC 9 to for NCC 3. It is clear from the test results, that as the quantity of replacement nano- OPC is increased, all mechanical strength parameters are increased. The ratio of cylinder strength to cube strength obtained was.784 times, but it is increased to.866 times in case of NCC 1. This indicates that around 8% increase in cylinder strength compared to conventional concrete. Similar trend was observed in the ratio of (f sp /f cu ), this was 8.7% for control concrete and 1.2% for NCC 9 concrete. This increase was observed in all nano concretes. The ratio of (f r /f cu ) was.19 for control (1.9%), this has been found almost more than 11% and in few cases 1.6%. The ratio of (f sp /f r ) was.8 in case of control and for all other nano concretes this ratio was more than the value obtained for normal concrete and had.929 for NCC 6 concrete. In general, all mechanical properties have increased drastically in nanoconcrete. The reason for such improvement in the strength is when the nano OPC is incorporated in the concrete mixture as a replacement material for OPC in concrete, the specific surface area that is available for hydration reaction is large. This enhances speedy and faster reaction. Moreover, the water to cement ratio was not increased and kept constant for all NCC and only the dosage of super plasticizer is changed. Therefore there is no chance for excess water to present in NCC. This is also the reasons for improvement in strength. But compared to increase in compressive strength, the tensile strength such as f sp and f r are not increased. However this could be increased by incorporation of strong fiber materials in the concrete mixture. Addition of nanocement does not show any appreciable increase in setting time. The initial setting time and final setting time for concrete mix were 3 and 4 minutes and for nanoconcretes these values were around 27 and 37 minutes respectively. This variation is within 1%. It was also observed, the strength of NCC after 24 hours i.e., immediately after demoulding was much higher than the control concrete. This is a great advantage at site because the demoulding time was greatly reduced. Also this early attainment of strength provides another advantage of this material such as R.Selvaraj and M.Amirthavarshini ijesird, Vol. II Issue VIII February 216/49

4 International Journal of Engineering Science Invention Research & Development; Vol. II Issue VIII February 216 it can be easily adoptable for any prefabricated structural elements, and subsequently it leads to fast building systems. There are no appreciable changes in the initial and final setting times. The changes are well within 1% in both cases. IV. CONCLUSION The fiber particles with more specific surface area involved in faster and speedy hydration system. The nano concrete attained much higher strength after 24 hours and therefore this nano-concrete is advantageous at site for early removal of shuttering and demoulding. Secondly, such a high strength material can very well be used for prefabrication of structural elements and leads to faster construction practices. REFERENCES 1. De la Garza Gutierrez.H,Munoz Mendoza.M.P, Chimal Valencia.O.A, Martienz Sanchez.R, De la Torre.S.D,Garcia Luna.A, Garcia Casillas.P,23, Optimizing milling parameters for refining Portland cement, Journal of Metastable and Nanocrystalline materials, 15-16, PP Feynman.R,196, There s plenty of rooms at the bottom Annual meeting of the west American Physical society, Engineering Science 23,PP Garcia Luna.A., 25, Micrometric refining process for obtaining cement particles. MX 23, PA Luna.A.G, November 29, Nanotechnology for sustainable development on cement industry proceedings of the 11 th NCB International seminar on cement and building materials, held at New Delhi, during 17-2, PP3-12. Table 1. Concrete mix design Materials used / m 3 Unit Control mix OPC Kg FC1 Kg FC2 Kg FC3 Kg River sand Kg Coarse aggregate 1mm and down Kg Super Size plasticizer L Water/Cement ratio R.Selvaraj and M.Amirthavarshini ijesird, Vol. II Issue VIII February 216/491

5 International Journal of Engineering Science Invention Research & Development; Vol. II Issue VIII February 216 Table 2. Characteristic strengths of Nano concrete after 28 days curing Designation Cube Compressive Strength f cu (MPa) Cylinder Compressive Strength f cy (MPa) Splitting Tensile Strength f sp (MPa) Flexural Strength f r (MPa) Control Table 3. Ratio of Characteristic strengths of Nano concretes Designation f cy /f cu f sp /f cu f r /f cu f sp /f r Control R.Selvaraj and M.Amirthavarshini ijesird, Vol. II Issue VIII February 216/492