Concrete Component

In Long Beach, California, some of the concrete pavements are being replaced by recycled rubber. They have several advantages over the concrete they are replacing, including greater pedestrian safety and easier maintenance [38]. 

A professor has teamed up with an entrepreneur tennis player and also the California Department of Transportation to resurface a tennis court with rubberized concrete. It is said to be the first time that such a surface has been used [39]. 

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In testing materials with high sound damping, the burst transmitter increases the signal-to-noise ratio to, typically, 12 dB. Typical applications honeycomb and concrete components, and air-coupled testing. 

The use of the stoichiometric coefficient v, guarantees that the reaction rate does not depend on the concrete component i considered. There are several possibilities regarding the selection of an appropriate scale. Frequently, the reaction volume Vr is used leading to a reaction rate rv which has the dimension [mol m-3 s]. 

In-plant impregnation of low-fired ceramic products. Low-fired ceramic products such as roof tiles, facing tiles and unglazed floor tiles are made water repellent by immersing them in dilute silicone masonry water repellents thereby preventing efflorescence and imparting water repellency (Wacker-Chemie, 1982). Prefabricated concrete components, plaster of paris and aerated concrete can also be treated in this way. 

ENVIRONMENT-CONSCIOUS MATERIALS DESIGN OF LIGHTWEIGHT PRECAST CONCRETE COMPONENTS WITH... 

The presence of some water-soluble gases in water, for example, CO3, O3, HjS is undesirable since they cause corrosion of metallic and concrete components of the systems used in water technology and industry. Thus, water degassing is one of the most efficient anticorrosion measures. This process is also necessary for feed waters used in boilers. For water degassing both thermal and chemical procedures are required. 

German Committee on Reinforced Concrete, Guidelines for the Protection and Repair of Concrete Component",... 

Significant advances have been made in the technology of CP of prestressed concrete components through extensive fundamental research and evaluation of CP systems that have been installed. Concerns about a loss of bond between... 

Bennett, J.E. and Schue, T.J. (1998). Cathodic Protection Field Trials on Prestressed Concrete Components, Final Report. FHWA Report. FHWA-RD-97-153. 

In the case of good properties of concrete components and correct mixture proportions the most important is shrinkage of the paste, which can appear at very early age, immediately after concrete placing. There are two gronps of reasons resrrlting... 

Cement paste has a great impact on the properties of concrete, however, these properties are related to the three concrete components cement, aggregate and water. The effect of cement paste should be discussed under the assumption that all these components are of high quality and their proportions in the concrete mixture are fairly well selected. 

A layer composed of CH and C-S-H gel is formed on the aggregate surface immediately after mixing of concrete components with water [17]. However, Zimbel-man [29] foimd the presence of small ettringite crystals. After the duplex film, the layer of portlandite crystals oriented perpendicularly with c axis to the aggregate surface is present [30,31]. This is an interlayer between the duplex film and cement matrix, and is formed dining 1-2 days after mixing of concrete components with... 

The internal and external concrete corrosion are distinguish. The internal concrete corrosion results from the concrete components themselves, first of all the... 

There is a cormnon opinion that corrosion of concrete needs the liquid environment or at least an atmosphere of high hmnidity. The transport of liquid through the concrete causes the sequence of processes, includiug at first the concrete components of the highest reactivity calcium hydroxide and calcium aluminate hydrates. One can thus conclude that the phase composition of cement has a great impact on the behavior of concrete in any aggressive environment. 

Hobbs [110] concludes that the expansion occurs only when the water soluble alkalis, expressed as Na20, is higher than 2.5 kg/m of concrete. It relates to the total alkali content, introduced with all concrete components. In this context, if cement replacement by fly ash does not allow reducing alkali content below this value, or even it becomes higher, then the addition of this pozzolana will not decrease the expansion, but even it can be increased [110],... 

The content of concrete component readily soluble is the other effloreseenee controlling factor, beside permeability. This refers generally to the cement paste, from which the sodium, potassium and calcium ions ate released to the pore solution in concrete. 

Finally, the so-called fillers constitute the last group of additives, which are, as a rule, inert and do not react in cement paste. The hmestone, added on a laige scale in Italy and in France was classified to this group a time ago [3]. As it is commonly known, the hmestone cannot be considered as an inert concrete component however, as compared with mineral additions from the former two groups, degree of CaCOj reaction in cement paste is rather poor. Nowadays, however, hmestones are recommended in the EN 197-1 standard as mineral additions, together with pozzolanic additives (see types of cements. Table 1.3). In 2007 the ratio of limestone cements produced in Europe and Turkey was 21.4 % (members of Cembureau) this corresponded to the annual output on the level of 56.2 million tons, in majority class 42.5. The ground quartz sand can be considered as typical filler, which does not react practically with calcium ions in cement paste, at ambient temperature. 

Each factory is comprised of two separate areas. In one area, the carpenters, painters, iron winders and moulding smiths, who have no contact with wet cement, carry out their work. In the other area, concrete prepared in the batch plant is transported by cranes to the moulding bays, where it is poured into moulds and vibrated automatically or manually (Fig. 1). The workers then level and sometimes also steam cure the concrete components. 

Medium and ultra-high strength bar, rod, and cable in prestressed and post-tensioned concrete components. 

Spacone El-Tawil 2004). The behaviour of composite beams (made of two components connected through shear connectors to form an interacting unit) is significantly influenced by the type of connection between the steel beam and the concrete slab. Flexible shear connectors allow the development of partial composite action. Thus, for accurate analytical response prediction, structural models of composite structures must account for the interlayer slip between the steel and concrete components. A composite beam finite element able to capture the interface slip is therefore an essential tool for model-based response simulation of steel-concrete composite structures. 

Besides the value of peak temperature, other conditions are also of importance the rate of temperature variation (heating and cooling), the number of heating/cooling cycles, material humidity and heterogeneity of concrete components behaviour in high temperature. Furthermore, there is no linear relationship between the temperature variation and its influence on a material s properties because there are several factors acting with different intensity and in opposite directions. 

When Portland cement is partly replaced by fly ash, SF or blast-furnace slag, then usually better flowability of the fresh mix is obtained and lower dosages of superplasticizers are possible. This is quite profitable from an economic viewpoint, because superplasticizer is an important part of the cost of concrete components. 

The same appHes to the formwork plans from which the details of the concrete components are derived. Here, the foundations of the apparatuses, pump sumps, ramps, floor ducts etc. are in the focus of the process engineer. 

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