Pr ese n te d bySY ED J EELA N I BA SH A

14 4 81 D 8 7 2 0

EFFECT OF DIFFERENT NANO-PARTICLES ON PHYSICAL AND MECHANICAL PROPERTIES OF

CONCRETE

Under the Guidance ofMs K SAILAJAAsst. Professor

Contents

Introduction Materials (properties and applications)Results and DiscussionsConclusionsReferences

Abstract

Nanoparticles like Al2O3, MnFe2O4, TiO2 and ZrO2 are used in this investigation. Nanoparticles with partial replacement of cement by 0.5 to 2 weight percent have been used as reinforcement. The results indicate that the strength and the resistance to water permeability of the specimens are improved by adding nanoparticles in the cement paste up to 2.0 wt. (%).Nanoparticles, as a result of increased crystalline Ca(OH)2 amount especially at the early age of hydration, could accelerate C-S-H gel formation and hence increase the strength of the concrete specimens. In addition, nanoparticles are able to act as nanofillers and recover the pore structure of the specimens by decreasing harmful pores. Curing of the specimens has been carried out in water for 7, 28 and 90 days after casting. Several empirical relationships have been presented to predict split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. In this study, Nanoparticles could improve mechanical and physical properties of the concrete specimens.

Introduction

Nanotechnology is the use of very small pieces of material by themselves or their manipulation to create new large scale materials.

At the Nano-scale material properties are altered from that of larger scales. The Nano-scale is the size range from approximately 1nm to 100nm. Nanotechnology is an enabling technology that allows us to develop materials with improved or totally new properties.

Nanoparticles:It is defined as a particle with at least one dimension less than 200nm. Nano-particles made of semiconducting material.

  Nanocomposites:

It is produced by adding Nano particle to bulk material in order to improve its bulk properties.

Nanotechnology in Construction: The construction industry was the only industry to identify nanotechnology as a promising emerging technology in the UK Delphi survey in the early 1990s .The importance of nanotechnology was also highlighted in foresight reports of Swedish and UK construction. Furthermore, ready mix concrete and concrete products were identified as among the top 40 industrial sectors likely to be influenced by nanotechnology in 10-15 years. However, construction has lagged behind other industrial sectors where nanotechnology R&D has attracted significant interest and investment from large industrial corporations and venture capitalists.

Why nanotechnology for concrete?

Improves the materials’ bulk properties. Ability to control or manipulate materials at the atomic

scale. NANOSCALE ATTACK ON ASR (ALKALI SILICATE REACTION)

To obtain thinner final products and faster setting time. Cost effectiveness. Lowered levels of environmental contamination.

Particle size and specific surface area related to concrete materials

Materials

Silicon dioxide:Nano-SiO2 could significantly increase the compressive strength of concretes containing large fly ash volume at early age, by filling the pores between large fly ash and cement particles. Nano-silica decreases the setting time of mortar when compared with silica fume (micro silica) and reduces bleeding water and segregation by the improvement of the cohesiveness.

Nano silica is only used in the high performance concretes (HPC), eco-concretes and self-compacting concretes (SSC) because of their high cost.

It is also added to increase the cohesiveness of concrete and to reduce the segregation tendency.

By adding nano silica to eco-concrete mixes to obtain an accelerated setting and higher compressive strength.

Aluminium oxide

It occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of which form the precious gemstones ruby and sapphire. Al2O3 is significant in its use to produce aluminium metal, as an abrasive owing to its hardness, and as a refractory material owing to its high melting point.

The Al2O3 nanoparticles with average diameter of 45 to 50 nm and average surface area of 30 m2/g.

Applications used as Filler

Glass CatalysesPurificationAbrasivePaint Composite fiber and Abrasion protection

Iron oxide

Ironoxide or ferric oxide is the inorganic com pound with the formula Fe2O3. It is one of the three main oxides of iron, the other two being iron oxide (FeO), which is rare, and iron oxide (Fe3O4), which also occurs naturally as the mineral magnetite. As the mineral known as hematite, Fe2O3 is the main source of iron for the steel industry.

The MnFe2O4nanoparticles with average diameter of 50 nm and average surface area of 28 m2/g were prepared by citrate nitrate auto combustion method.

ApplicationsUsed in Medicine

Photo catalystsMagnetic recordingPigment

PolishingIron industries

Zirconium dioxide

Zirconium dioxide (ZrO2) sometimes known as zirconia , is a white crystalline oxide of zirconium. Its most naturally occurring form, with a monoclinic crystalline structure, is the mineral baddeleyite.

The ZrO2 nanoparticles with average diameter of 15 to 20 nm and average surface area of 45 m2/g.

Applications

The main use of zirconia is in the production of ceramics, with other uses including as a protective coating on particles of titanium dioxide pigments, as a refractory material, in insulation, abrasives and enamels

Titanium dioxide

Titanium dioxide occurs in nature as the well-known minerals rutile, anatase and brookite, and additionally as two high pressure forms, a monoclinic baddeleyite-like form and an orthorhombic α-PbO 2-like form, both found recently at the Ries crater in Bavaria. It is mainly sourced from ilmenite ore. This is the most widespread form of titanium dioxide-bearing ore around the world.The ZrO2nanoparticles with average diameter of 15 to 20 nm and average surface area of 45 m2/g.

ApplicationsUsed as Pigment

Photo CatalystOther applications like protection and used in solar power

Results and Discussion

Results of split tensile test for partial replacement of cement 0, 0.5, 1,1.5 and 2 wt. (%).

The test results for 4 materials for 7, 28 and 90 days are given in the tabluar form

Sample Designation

Nano Al2O3 particle (%)

7 days 28 days

90 days

C0 (control) 0 1.8 1.9 2.2

N1 0.5 2.3 2.5 2.7

N2 1.0 2.2 2.8 3.1

N3 1.5 2.4 2.6 2.9

N4 2.0 1.6 1.7 2.0

Sample Designation

Nano MnFe2O4 particle (%)

7 days 28 days

90 days

C0 (control) 0 1.6 1.7 2.4

N1 0.5 2.2 2.5 2.8

N2 1.0 2.7 3.2 3.6

N3 1.5 2.5 2.8 3.2

N4 2.0 1.7 1.9 2.6

Sample Designation

Nano TiO2 particle (%)

7 days 28 days 90 days

C0 (control) 0 1.5 1.8 2.3

N1 0.5 2.3 2.6 2.9

N2 1.0 2.8 3.0 3.3

N3 1.5 2.6 2.7 3.0

N4 2.0 1.9 1.9 2.4

Sample Designation

Nano ZrO2 particle (%)Split tensile

7 days 28 days 90 days

C0 (control) 0 1.5 1.8 2.3

N1 0.5 2.5 2.9 3.4

N2 1.0 3.0 3.3 3.6

N3 1.5 2.9 3.0 3.2

N4 2.0 2.0 2.1 2.4

Comparison of the results from the 7, 28 and 90 days samples shows that the compressive strength increases with nano-Al2O3 particles up to 1.0% replacement (N2) and then it decreases, although the results of 2.0% replacement (N4) is still higher than those of the plain cement concrete (CO). It was shown that the use of 2.0% nano-Al2O3 particles decreases the compressive strength to a value which is near to the control Concrete.

The results show that the compressive strength increases by adding MnFe2O4 nanoparticles by 0.5 wt% replacements and then it decreases. MnFe2O4 nanoparticles accelerate consumption of crystalline Ca(OH)2 which quickly are formed into C-S-H during hydration of cement specially at early ages due to the high reactivity of these nano-particles.

N series blended concrete are due to the rapid consuming of Ca(OH)2 which was formed during hydration of Portland cement specially at early ages related to the high reactivity of nano-TiO2 particles. As a consequence, the hydration of cement is accelerated and larger volumes of reaction products are formed. Also nano-TiO2 particles recover the particle packing density of the blended cement, directing to a reduced volume of larger pores in the cement paste.

Conclusions

 About Al2O3

The results show that the nano-Al2O3 particles blended concrete had significantly higher compressive strength compare to that of the concrete without nano-Al2O3 particles.It is found that the cement could be advantageously replaced with nano- Al2O3 particles up to maximum limit of 2.0% with average particle sizes of 45 nm. Although, the optimal level of nano-Al2O3 particles content was achieved with 1.0% replacement. Partial replacement of cement by nano-Al2O3 particles decreased workability of fresh concrete; therefore use of super plasticizer is substantial.

About MnFe2O4

The results showed that concrete specimen reinforced with MnFe2O4 nanoparticles had higher compressive strength compared to that of the concrete without MnFe2O4 nanoparticles.

It was found that the cement could be advantageously doped with MnFe2O4 nanoparticles up to maximum limit of 1% by weight of cement with average diameter of 49 nm. However, the maximum value of compressive strength was achieved with 0.5 wt% doped MnFe2O4 nanoparticles.

The addition of MnFe2O 4 nanoparticles with 1.5 wt% and 2 wt% led to a compressive strength lower than the control specimen.

About TiO2

The results show that the nano-TiO2 particles blended concrete had higher compressive strength compared to that of the concrete without nano-TiO2 particles.

It is found that the cement could be advantageously replaced with nano-TiO2 particles up to maximum limit of 2.0% with average particle sizes of 15 nm when the specimens cured at saturated limewater for 28 days.

The optimal level of nano-TiO2 particles content was achieved with 1.0% replacement for the specimens cured in water 7, 28 and 90 days.

About ZrO2

As the content of ZrO2 nanoparticles is increased up to 2 wt%, the compressive strength and split tensile strength of concre specimens is increased.

This is due to more formation of hydrated products in presence of ZrO2 nanoparticles.

ZrO2 nanoparticles could act as nano fillers and improve the resistance to water permeability of concrete at 7 and 28 days and curing.

At 2 days of curing, the coefficient of water absorption is increased by increasing the nanoparticles content up to 2.0 wt. (%) since the specimens require more water to rapid forming of hydrated products.

CONCLUSION

Well dispersed nano particles increase the viscosity of the liquid phase, improves the segregation resistance and workability of the system.

Accelerates the hydration.

Better bond between aggregates and cement paste.

Improves the toughness, shear,tensile strength and flexural strength of concrete.

References:•“Study of effect of Al2O3 nanoparticles on the compressive strength and workability of blended concrete” by Agarkar, S. V. and Joshi, M. M.International Journal of Current Research Vol. 4, Issue, 12, pp. 382-384, December, 2012.

•“Computer-aided prediction of physical and mechanical properties of high strength concrete containing Fe2O3 nanoparticles” by Farzad Soleymani, Journal of American Science 2012;8(7).

•“The filler effects TiO2 nanoparticles on increasing compressive strength of palm oil clinker aggregate-based concrete” by Farzad Soleymani, Journal of American Science, 2012;8(6).

•“The effects of ZrO2 nanoparticles on physical and mechanical properties of high strength self compacting concrete” by Ali Nazari, Shadi Riahi, Department of Technical and Engineering Sciences, Islamic Azad University, Saveh Branch, Saveh, Iran. Materials Research. 2010; 13(4): 551-556.

•Nazari A. “The effects of curing medium on flexural strength and water permeability of concrete incorporating TiO2 nanoparticles”. Mater Struct, 2011, 44(4): 773–786.

•Nazari A, Riahi S. “Microstructural, thermal, physical and mechanical behavior of the self compacting concretem containing SiO2 nanoparticles”. Mater Sci Eng A, 2010, 527: 7663–7672.

•Nazari A, Riahi Sh, Shamekhi SF, Khademno A., “The effects of incorporation Fe2O3 nanoparticles on tensile and compressive strength of concrete”. Journal of American Science, 2010; 6(4): 90-93.

Thank you