Carbon grid

Abstract: Lightweight foamed concrete which is produced with Portland cement is noble in compression but fragile in tension because it comprises various micro pores that tend to crack. The micro cracks start to transmit in the cement matrix when excessive load is transferred. Hence this research project explored the potential use of textile carbon grid laminates reinforced lightweight foamed concrete in terms of its mechanical properties. It should be pointed out that one of the major problems faced in reinforced lightweight concrete construction is the corrosion of reinforcing steel which ominously distresses the lifespan and robustness of concrete assemblies. Henceforth, fiber glass strip laminates as a replacement to welded wire mesh can commendably abolish the delinquent of decomposition as they are protected to corrosion. There are 3 densities of foamed concrete of 800kg/m3, 1100kg/m3 and 1400kg/m3 will be prepared will with inclusion of 3 different types of fiber glass strip laminates which are 130g, 145g and 160g (weight per square meter). The components that will be evaluated are failure modes, performance index, and microscopy study. When the basis weight of fiber glass strip laminates increases (from 130g to 160g), the greater the tensile bond strength of lightweight foamed concrete. As the load increases on the lightweight foamed concrete, a flew in the matrix may spread over the specimen cross-section. The mechanics of this spread depends on the size of the flaw, the properties of the fiber glass strip laminates reinforcement and matrix toughness. If lightweight foamed concrete is adequately reinforcing, the bridging fiber glass strip laminates will share the load and transfer it to the other parts of the specimen.

Abstract: A transmission electron microscope (TEM) micro-grid includes a pure carbon grid having a plurality of holes defined therein and at least one carbon nanotube film covering the holes. A method for manufacturing a TEM micro-grid includes following steps. A pure carbon grid precursor and at least one carbon nanotube film are first provided. The at least one carbon nanotube film is disposed on a surface of the pure carbon grid precursor. The pure carbon grid precursor and the at least one carbon nanotube film are then cut to form the TEM micro-grid in desired shape.

Abstract: Rising traffic loads have increased the requirements for the load-carrying capacity of bridges significantly. Therefore, the calculated shear capacity of many existing bridge deck slabs without shear reinforcement is not sufficient. Besides common strengthening methods, the use of textile reinforced concrete (TRC) offers an innovative alternative for strengthening measures. Therefore, the influence of an additional TRC-layer in the tension zone on the shear capacity has been investigated by full scale shear tests on two single span reinforced concrete slab strips (b = 0.5 m; h = 0.28-0.32 m; l = 4.4 m) at the Institute of Structural Concrete at RWTH Aachen University. The tests on a non-strengthened slab strip served as reference for two further tests on a slab strip strengthened by a TRC-layer with two and three layers of carbon grid, respectively. The test results revealed a clear participation in load-bearing of the strengthening layer with an increase of the shear capacity of up to 16 %. The paper presents the test results with regard to the effectiveness as well as the advantages and possible fields of application of this innovative strengthening method. Key-words: Reinforced concrete, shear, slabs, strengthening, textile reinforced concrete, experimental investigations. INTRODUCTION The road network has the function as the lifelines of society and is essential for infrastructure, transport and economy. One of the neuralgic nodes of the road network is bridges. Many bridges in Germany and other European countries were built in the 1960s and 70s (Figure 1, [1]) making assessment, maintenance and refurbishment of the existing network increasingly important [2]. In Germany, the Federal trunk road network includes in total 39106 bridges with a total bridge deck area of 30.03 km2 (state: 01.09.2012, [1]), from which more than one third are more than 40 years old. Especially the enormous increase of traffic loads and transport performance of goods transport shown in Figure 2 raises the question, whether the existing bridges have sufficient capacity to resist the continuously increasing demands [2]. Until 2025, a further increase of heavy goods transport is expected (Figure 2) leading to a further increasing potential market for innovative strengthening methods.