Papers by Keyword: Smart Concrete

Abstract: Smart and resilient concrete structures will require building materials such as cements that sense flaws. One mechanism of crack detection in structures is monitoring their electrical conduction. Two mechanisms of charge in cement is ionic movement and moisture diffusion. Carbon rich electrically-conducting char is produced by pyrolyzing rice husks and can be used to enhance electrical conduction in cement. This paper studies the evolution of electrical properties in ordinary Portland cement added with up to 15 wt% rice husk-derived biochar. Resistance of cements decreased with increasing biochar addition while moisture loss and resistance both increase as curing time increases. Cement with 15 wt% biochar experiences the largest moisture loss and the most conducting. This suggest charge transport along percolation paths of biochar particles is dominant mechanism in these materials. Electron microscopy and energy dispersive spectroscopic studies reveal formation of Ettringite phase and good wetting/bonding at the interface of biochar particles and cement.

Abstract: This article deals with the measurement system and the use of special cement composites with carbon particulates. The type of carbon particulates consequently determines the electrical properties of cement composite material. These materials can be used for electric heating, electromagnetic shielding or stress measurement. Strain properties can be used to measure the deformation of concrete structures (bridges, beams, pillars) or for weighing-in-motion of road vehicles. This article describes novel laboratory equipment which is designed for multichannel dynamic and long-period material stability measurements.

Abstract: Smart concrete is an innovative material because it can serve as a sensor without any additional sensors in it. It is reinforced with carbon fiber that has gone through the pyrolysis process at high temperature to produce carbon content above 90%. The carbon fiber used in this study was Polyacrylonitrile. The working principle of carbon fiber sensor works piezoresistivity that respond to changes in mechanical (stress and strain) to electrical impulses. The resistivity changes that will be converted into units of load on the display circuit system. Key to success of this research was the concrete formulations and systems were sensitive and accurate readings so that any small change in resistivity could be directly detected. Variations in carbon fiber were added to the 0-1% by weight of cement with interval 0.5. Fly ash was added as a filler to reduce the use of cement. Results obtained from dynamic cyclic testing showed that the compressive strength was the best in the concrete without carbon fiber, then decline in line with the increased number of carbon fiber. But inversely proportional to the resistivity of the concrete produced. Smart concrete must have a high sensitivity to changes in stress / strain, it should also meet the required concrete strength both press and flexible to avoid initial crack.

Abstract: It’s been almost a decade that the idea of smart materials has attracted man’s attention. These materials are capable of responding to their surrounding environment and of adapting to it. The development pace of construction materials has also been towards multi-purpose and smart materials, which would ultimately result in manufacturing phase matters. In fact, the existence of smart structural materials and systems has played a substantial role in developing the idea of the smart control of a construction. These materials can improve designing methods and the construction of buildings. In the sustainable buildings design approach (a new approach to designing buildings which should meet a high level of environmental standards with an emphasis on the costs of their useful lifespan), such highly efficient materials are used because they are more adaptable to the environment and increase a building’s useful lifespan. In this article, some of the smart materials used for the façade are introduced and their performances will be studied. It is concluded that using such technologies requires less energy and very little amounts of chemicals and detergents which could be a step taken towards achieving sustainable architectural and environmental goals.

Abstract: This paper describes some of the characteristics of nano-materials are discussed nano SiO2, silica fume and nano-scale carbon-fiber reinforced concrete to improve strength and durability of the role of nano-SiO2, silica and carbon nano-fibers can be prepared as an admixture of high performance concrete, nano materials can also be used as a preparation mixed with Division of concrete with special features, such as metal oxides can be prepared by adding nano smart concrete and green concrete, metal powder can be prepared by adding nano electromagnetic shielding concrete.

Abstract: As a smart material, the study of shape memory alloy in civil engineering mainly in the self-monitoring and self-repairing of concrete beams, earthquake resistance and reinforcement of concrete columns, seismic damping of concrete structures, etc. The development of shape memory alloy and its main features are outlined; research progress of the shape memory effect and superelasticity of shape memory alloys in smart concrete application are introduced; the factors which affect the development of smart concrete structure and the development direction are pointed out.

Abstract: In this paper, some smart sensors or material used to make the smart sensors, such as piezoresistance composite, piezoelectric polymer, piezoelectric cement and corrosion monitoring sensor, developed by Harbin Institute of Technology were introduced. Piezoresistance composite is made with carbon nanotube and resin, one character of the work is the carbon nanotube is orientation arranged by magnetic field. Piezoelectric polymer is made with PZT particles and PVDF, in order to improve its performance a few carbon nanotube are also mixed in the composite. Piezoelectric cement is one kind of sensing material whose primary raw materials are cement and piezoelectric ceramic particles (or fiber). The sensing performance of piezoelectric cement is coming from its functional phase, the piezoelectric ceramic. The corrosion monitoring sensor is made with solid-state reference electrode, whose surface is one kind of binary alloy membrane produced with physical vapor deposition technology. The main producing technology, performance and applications of above sensors were introduced in this paper.

Abstract: Smart concrete is the product of modern building materials combining with modern technology and the advanced stage of the traditional concrete development. But the smart concrete material is currently in the research and laboratory stage and is far away from large-scale practical application stage. The history and developing status of the smart concrete were reviewed. The definition and classification of the smart concrete were discussed in detail. The developing trend and prospects of the smart concrete were analyzed and some problems were proposed.

Abstract: Shape memory alloy (SMA) has many potential applications as an actuator in smart material systems due to its abilities of shape memory, pseudo-elasticity, high damping and wear resistant. In this paper, a smart concrete beam has been developed by taking advantage of the shape memory effect of SMA and the characteristic of applying large forces on the resisting member in the transformation of SMA on heating. Deformation behavior and influence of factors on the deformation behavior of SAM smart concrete beam were investigated experimentally. Actuation mechanics of SMA was analyzed. Experimental results show that SMA wires significantly increase structural survivability and allow structural to recover from residual deformation by damaged earthquake and typhoon, and the crack almost closes completely after electrically heating the SMA wires. The number or areas of SMA wires has no influence on the tendency of deformation during loading and the tendency of reversion by heating. An increasing of the initial pre-strain of SMA wire can significantly improve the capacity of self-restoration of SMA concrete beams, but the steel main bars play a very negative role in reducing residual deformation.

Abstract: Smart concrete technology provides a new alternative way for health monitoring of reinforced concrete structures. In this paper, the piezoresistivity of two kinds of smart concrete filled with carbon black or carbon fiber was studied, and two types of embedded sensors were fabricated using the smart concrete with favorable piezoresistivity. The sensing performance, the measuring methods and the response to environmental temperature and humidity of embedded sensors were investigated. A compensation circuit was incorporated to reduce the effect of temperature and humidity on the output of embedded sensors. The sensors were embedded in concrete beams and columns to monitor the structural compressive strain under field conditions. Experimental results indicate that the embedded sensors fabricated using smart concrete filled with carbon black or carbon fiber feature favorable sensing performance (gauge factors are 55.28 and 138 respectively). The self-sensing concrete components embedded with these sensors can realize the monitoring of their local compressive strain. It therefore can be concluded that the prepared smart concrete and the developed embedded sensors have great potential to be used for health monitoring and damage assessment of concrete structures.