Concrete: cellular concrete of clay- gypsum and invention of light weight concrete Ferro concrete: this concrete is made up of a layer of fine mesh wire saturated with cement. Gunite: or commonly referred as a shot crete. This type or form of concrete is most commonly used in areas where formwork is limited or hard to use. Shoring up exposed vertical excavations, banks or surfaces susceptible to collapse. For example, vertical soil or rock surfaces.
The hydrothermal technique usually gives hydroxyapatite powders a high degree of crystallinity. However, need high temperature and the obtained powders are usually in agglomeration and the size distribution are usually in wide range. The main advantage of emulsion technique is the simplicity of the process, good crystallinity product without high temperature, and favours the formation of small crystallites with a sufficient narrow size distribution. Sol-gel synthesis of hydroxyapatite has many advantages, which include high product purity, homogeneous composition, and low synthesis temperature. When the mass production of high crystalline hydroxyapatite is required, mechanochemical treatment is more suitable.
Shotcrete is one of the concrete that are more flexible and it has high strength, durability, low permeability, excellent bond and limitless shape possibilities. These properties allow shotcrete to be used in most cases as a structural material, for instance in complex shaped structures that have placing in difficult conditions areas. Shotcrete undergoes a unique method of placement and compaction simultaneously due to the force at which it is projected from the nozzle of the hose pipe. It can be press tightly together (embedded) onto any type or shape of surface, including vertical or overhead areas. Shotcrete can be significantly used in almost any concrete project and in a characteristic manner that results in a significant savings of time and money (this makes it economical).
It works well in an outdoor setting because of its weight, hardness and overall toughness. The major drawback is that since it is a comparatively pure form of iron, it corrodes fairly quickly when subjected to moisture and air. Most modern furnishings with metal are mostly made of stainless steel, such as slides, hinges, supports and body pieces. Since it has a high tensile strength it can be used in hollow tubes, which reduce the weight and increases user accessibility. Aluminium is lightweight and resistant to corrosion and as a result, it is used extensively in stamped and cast furniture, particularly in molded chairs.
Metal Matrix Composites The demand for materials having high strength and high toughness and capable of operating effectively under adverse conditions has led to the development of a new generation of materials known as Metal matrix composites. Attractive physical and mechanical properties that can be obtained with metal matrix composites (MMCs), such as high specific modulus, strength and thermal stability have made them the materials of the future and this fact has been documented extensively. MMCs combine metallic properties (high strength and high modulus), leading to greatest strength in shear and compression and higher service temperature capabilities. Interest in MMCs for aerospace, automotive and other structural applications has
Thermoplastics have a lot of advantages for engineering design applications. These advantages are high ductility, toughness, etc. Typical examples of thermosets include polyethylene (high or low density), polypropylene, nylon and acrylics. [Adjaottor,
Concrete quality strongly affects the resistivity readings in terms of water/cement ratio, curing and extenders used. A Wenner Probe, which consists of four equally spaced probes, is typically used to measure concrete resistivity. Potential difference in concrete is measured by the inner two probes while current is passed through the concrete by the outer two probes. Resistivity readings when combined with Half - Cell Potential measurements were found to be very accurate. It must however be mentioned that this technique is very sensitive towards humidity and temperature
(Construction-Chemicals.Basf.com,2013). Concrete recycling is also becoming more and more popular with a shift in attitudes and awareness. Concrete recycling involves gathering concrete rubble after demolition and then processing the remainders into high-quality aggregates. This reduces the impact from aggregate collection. However, most countries as of now do not recycle a large percentage of the concrete; with the leaders being Netherlands and UK both countries which have a consumption of recycled aggregate above 20% (Jahren, 2013).
This is seldom counterbalanced by the much lower volumes of concrete required in a dam of given height. 1.7. Design and Construction of New embankment Dams: The design and construction of embankment dams is complex because of the nature of the varying foundation conditions and range of properties of the materials available for
Figure 1.1- Simple Rectangular Shear Wall 2. Coupled shear wall : In these type of shear wall, two structural walls are joined together through relatively short spandrel beams, thus increases the stiffness of resultant wall, In addition the structure dissipate most of energy by yielding the coupling beams with no structural damages to the main walls. Figure 1.2- Couple Shear Wall 3. Rigid frame shear walls: The interaction of rigid frames and simple shear walls of a tall building. The deflection of the frame is in shear mode, but the wall deflection is in the bending mode.