Future of Multifunctional Nanoconcrete

Concrete structures constitute a large portion of civil infrastructures, but their reliability is relatively low because of wide material discreteness and complex service environment. Consequently, the safety of concrete structures is an important problem being paid attention to at all times in civil engineering field. Therefore, it is necessary to take reasonable measures to monitor the state of concrete structures. In order to monitor the performance and state of concrete structures during...

Current Approaches for Dispersing CNTs in Cement Based Materials

Some works have reported disappointing results, showing little or no improvement in cement-based materials' properties by adding CNTs because of insufficient or poor dispersion of CNTs. For example, De Ibarra et. al. 2006 observed that a non-uniform distribution of the CNTs' bundles (Fig. 5) within the matrix provokes a decrease in the mechanical properties of the materials. Because the utilized SWNTs are straighter and more defect-free structures than the utilized MWNTs, SWNTs have a lower...

Electrical and Piezoresistive of CNTs

The unique electrical properties of CNTs are to a large extent derived from their 1-D character and the peculiar electronic structure of graphite. Resistance occurs when an electron collides with some defect in the crystal structure of the material through which it is passing. The defect could be an impurity atom, a defect in the crystal structure, or an atom vibrating about its position in the crystal. Such collisions deflect the electron from its path. But the electrons inside a CNT are not...

Dispersion of SWCNT for Use in Cementitious Composites

Dispersion of nanomaterials is one of the key issues facing the development of all nanocomposites. Nanomaterials need to be evenly dispersed in the matrix material in order to produce repeatable and consistent effects. Well dispersed nanomateri-als may also be expected to produce desirable properties with a lower mass content. Successful dispersion may, however, also be difficult to obtain as the very high surface areas of nanomaterials can cause them to adhere together due to electrostatic...

Sample Image after Nanoindentation

The nanoindentation on both aggregate and mastic phases of asphalt concrete cube sample were performed using a nanopositioner attached with our nanoindentation equipment. The photographs of asphalt samples after nanoindentation are shown in Figures 8(a) and 8(b). It can be seen that a significant impression on mastic sample from Figure 8(a). Where as the impression on aggregate is recovered quickly as shown in Figure 8(b). Aggregate sample is much stronger than the mastic sample and hence a...

Nanoporous Thin Film Technology to Improve Concrete Performance

As discussed above, most nanotechnology research has focused on characterizing concrete when nanosilica particles are dispersed in the cement paste. Nanoparti-cles added during cement mixing affect only the microstructure of the paste without making any significant improvement in the strength of the interfacial transition zones (ITZ). The addition of nanoparticles as nanoporous thin films (NPTF) on aggregate surface before concrete mixing was found to be an effective way to improve the ITZ and...

Structure and Dispersion of CNTs

Structurally, CNTs can be approximated as ''rolled-up'' sheets of graphite (Fig.1). In this graphite, sp2 hybridization occurs, where each carbon atom is connected evenly to other three carbon atoms (120 ) in the xy plane, and a weak n bond is present in the z axis. The sp2 set forms the hexagonal (honeycomb) lattice of a sheet of graphite Dresselhaus et al. 2000, Odom et al. 2000, Terrones 2003 . Varieties of CNTs include single-walled nanotubes (SWNTs) and multi-walled nanotubes (MWNTs)....

Nanoindentation for Moisture Damage Study

In a nanoindentation test, the movement of a diamond probe in contact with a sample surface is measured by applying an increasing load. Time, load, and displacement are recorded during the test. The elastic and plastic properties of the sample are determined from the load-displacement data. Stiffness and hardness are the most common mechanical properties measured from indentation data. Stiffness is the ratio of stress to strain. Hardness is the resistance to permanent deformation. It is defined...

Mechanical Properties of Nanocomposites

The CNTs' enhancement capability to the nanocomposites (i.e. CNTs reinforced cement-based materials) depends on many factors, among them the quality of CNTs' dispersion, the final aspect ratio (whether the nanotubes were shortened as a result of disaggregative treatment), CNTs' content level, CNTs' intrinsic structure and properties, composition and structure of matrix, and the interfacial bonding condition between CNTs and matrix. Therefore, very different results have been reported on the...

References

Pull-off forces measured between hexadecanethiol self-assembled monolayers in air using an atomic force microscope analysis of surface free energy. Journal of Adhesion Science and Technology 16 7 , 845-868 2002 Du, B., Tsui, O., Zhang, Q., He, T. Study of Elastic Modulus and Yield Strength of Polymer Thin Films Using Atomic Force Microscopy. Langmuir 17 11 , 3286-3291 2001 Frisbie, C.D., Rozsynai, L.F., Noy, A., Wrighton, M.S., Lieber, C.M. Functional Group...

Nanoclays in Asphalt Binders and Mixtures

Pavement researchers have suggested that nanoclays have interesting performance enhancing characteristics that could improve the mechanical strength properties of both asphalt binders and mixtures. In one of such notable studies, it has been shown that polymeric nanoclay composites can improve the physical, chemical and mechanical properties of asphalt binder systems when the nanoclays are evenly dispersed at the nanoscopic level within the binder system Jahromi and Khodaii 2009 . Nanofil-15...

Incorporation of NanoSiO during Mixing

Research showed that the compressive and flexural strengths of cement mortars containing SiO2 and Fe2O3 nano-particles were both higher than those of plain cement mortar Li et al. 2004, Hui Li 2004 . The experimental results show that the compressive strengths of mortars with nano-silica NS were all higher than those of mortars containing silica fume at 7 and 28 days. An addition of 10 nano-SiO2 with dispersing agents resulted 26 increase of 28 days compressive strength whereas the increase of...

CSH Understanding Using Crystal Structures

Faucon et al. 1996 used MD simulations to understand the NMR data concerning C-S-H. Using the Tobermorite structure they observed that in the absence of calcium atoms, no break in the chain is observed. The presence of Ca causes partial rupture of Si chains. Faucon et al. 1997 also showed that Al atom can be substituted in the place of Si atom. Such substitution is possible where the bridging Si is energetically less stable. Faucon et al. 1999 used the similar substitutions using Na....

Modeling to Find the Amorphous Structure of CSH

The computed bulk properties of Tobermorite crystal structure is 4 to 5 times the bulk properties of cement paste as reported by Janakiram Subramani et al. 2009 . Plassard et al. 2004 observed a bridging silicon Si atom missing in the silicate chains thereby forming dimers or pentamers. If the missing Si atom occurs after every two Si positions in the chain it is called a dimer whereas if the missing Si atom occurs after every five Si positions in the chain it is called a pentamer. To verify...

Selfsensing Concrete Structures

2.4.1 Preparation of Concrete Column with Embedded CBCC Sensor Epoxy encapsulated CBCC sensor with shape of 30x40x50 mm was prepared with the developed methods, and the properties of CBCC sensor were shown in table 1. Resistivity , , Gage factor iicm Concrete columns were made with C40 and C80 concrete respectively for the aim of studying the strain sensing property of CBCC sensors in different strength grades of concrete matrix. The cement used for C40 and C80 concrete were Portland cement...

Introduction

Concrete is used extensively in constructions for buildings as well as in highways. The durability and long life-cycle of concrete is affected by minute cracks due to shrinkage and load-related stress. This is due to the relative lack of tensile strength compared to the compressive strength of concrete. Cement pastes which exhibit BELL 4190 University of Arkansas, Fayetteville, AR 72701, USA e-mail rps uark.edu BELL 4190 University of Arkansas, Fayetteville, AR 72701, USA e-mail kdhall uark.edu...

Optimization of Clay Addition for the Enhancement of Pozzolanic Reaction in Nanomodified Cement Paste

This chapter presents a process for obtaining nano-size silicate platelets for use in cement paste from exfoliating Cloisite Na clay particles. The resulting silicate platelets require all surface electrical charges to be neutralized. The results showed that this is achievable through the use of organic ammonium chloride surfactant. The exfoliation process was evaluated through the use of X-ray diffraction and the optimum stable concentration of organic ammonium chloride was...

Flexural Fatigue Performance of Concrete Containing Nanoparticles for Pavement

3.3.1 Materials and Mixture Proportions The materials and fabrication methods were same to that shown in section 2.2. Six kinds of mixtures are cast in this study. The water binder ratio used for all mixtures is 0.42, where the binder weight is the total weight of cement and nano-particles. Sand ratio is 34 . The mixture proportions for cubic meter of concrete are given in Table 12. Herein, PC denotes plain concrete. PPC denotes the concrete containing PP fibers in the content of 0.9 kg m3....

Dispersion and Morphological Characterization of the Nanoclaymodified Asphalt

3.2.1 Dispersion Characterization Separation Tube and X-Ray Dispersion After the preparation of the Nanomer and Cloisite-modified PG 64-28 asphalt binders, two techniques are employed to evaluate the extent of dispersion of the Nanomer and Nanocloisite particles within the PG 64-28 asphalt binder system. The two techniques are the separation tube method and the X-ray dispersion method XRD . The separation tube method involves the application of a thin-walled metal tube used to ascertain the...

Characterization of Asphalt Materials for Moisture Damage Using Atomic Force Microscopy and Nanoindentation

Asphalt materials have traditionally been characterized for moisture damage at component microscale and laboratory specimen macro scales. Though characterizations at such scales are commendable and often necessary and well understood by the pavement engineering community, there are problems which cannot be solved using micro and macroscale characterizations. For example, moisture damage in asphalt pavement is caused by moisture interaction with asphalt-aggregate bonds, which occurs at...

Reactive Powder Concrete RPC

A process for synthesis of cement with nano-scale particle sizes has recently been developed. It is demonstrated that nanocements with nano-scale particle sizes and varying phase compositions can be tailored. Addition of nano-cement in reactive powder concrete RPC systems has the potential to further enhance the properties of an already optimized system. The replacement of a small fraction of the conventional cement with these nano-cements causes faster cement hydration reaction and reduces the...

Pavements and Nanotechnology

Chemistry is the science concerned with the composition, structure, and properties of matter, while physics is the science that deals with concepts such as force, energy, and mass with the goal of understanding the natural world. Engineering seeks the creative application of scientific principles to design, develop, manufacture and operate structures, machines, manufacturing processes or works while acknowledging issues around economics of operation and safety to life and property. Pavement...

Abrasion Resistance of Concrete Containing Nanoparticles 321 Materials and Mixture Proportions

The cement used is Portland cement P.O42.5 . Fine aggregate is natural river sand with a fineness modulus of 2.4. The coarse aggregate used is crushed diabase with diameter of 5 25mm. UNF water-reducing agent one kind of P -naphthalene sulfonic acid and formaldehyde condensates, China is employed to aid the dispersion of nano-particles in concrete and achieve good workability of concrete. The defoamer, tributyl phosphate made in China is used to decrease the amount of air bubbles. The...

Nano Clay Composite

Nanoclay particles have shown promise in enhancing the mechanical performance, the resistance to chloride penetration, and the self-compacting properties of concrete and in reducing permeability and shrinkage Chang et al. 2007, Kuo et al. 2006, Morsy et al. 2009, He and Shi 2008 . Organo-modified montmorillonites OMMT which have been widely used in polymer clay nano-composites PCN are employed as fillers and reinforcements in cement mortars Kuo et al. 2006 . The hydrophilic montmorillonite MMT...

Improved Materials

Nanotechnology partly focuses on the creation of new materials at the molecular level with significantly improved properties on the mechanical and related levels Chong 2003 . Through judicious application of nanotechnology techniques material behavior problems can be addressed through engineering techniques on the nano-scale. This allows the molecular properties of materials to be better understood, and the molecular properties of materials to be changed, leading to improved behavior of the...

Design of CSH Nucleation and Growth

The most exciting cement mineral and which has also led to the largest collection of work is undoubtedly C-S-H. Unfortunately this hydrate is difficult to characterize and to quantify during the cement hydration. These problems were and are still basically the greatest barrier to overcome in order to perfectly seize the link existing between the development of this hydrate and all the mechanical changes occurring in a cement paste. The lack of investigation techniques was at the origin of many...

Dynamic Shear Rheometer DSR

In Fig. 5 and 6, two bar charts showing the DSR trends are presented here to establish the rheological characteristic of the original and nano-modified PG 64-28 asphalt binder systems. With 2 and 4 nanoclay addition to the PG 64-28 asphalt binder, the G value increased by an average of 66 and 125 , respectively, from that of the original heat mixed PG 64-28 asphalt binder. When 2 of Nanoclay B was added, the trend showed an average G increase of 184 while increasing the Nanoclay B additive to 4...

Preface

Nanotechnology was conceived with a vision to advance our understanding and control of matter at nanoscale toward national economic benefit, national and homeland security, and improved quality of life. It enables changes at the molecular level to optimize material behavior and performance of civil infrastructure systems such as buildings and highways at the macro-functional level. The resulting nano-modified high-performance construction materials and systems are characterized by higher...

Application of Nanoscience Modeling to Understand the Atomic Structure of CSH

Hall, Vikramraja Janakiram Subramani, and Shanique J. Murray Abstract. Concrete is used extensively for constructing buildings and highways. In order to enhance macroscopic mechanical properties tensile strength it is necessary to understand the structure and behavior of C-S-H gel at the atomic level. Current status in nanoscience modeling of C-S-H is reviewed. The computational tools available and their limitations are also surveyed. Application of nano science in...

Multifunctional and Smart Carbon Nanotube Reinforced Cement Based Materials

Nanotechnology has changed and will continue to change our vision, expectations and abilities to control the material world. These developments will definitely affect the field of construction and construction materials. Carbon nano-tubes CNTs are considered to be one of the most beneficial nano-reinforcement materials. The combination of high aspect ratio, small size, low density, and unique physical and chemical properties make them perfect candidates as reinforcements in...