The concrete should be used as efficient as possible. Nowadays researches efforts are continuously looking for new, better and efficient construction method. Various theories related to the analysis of structural elements reduced the self-weight of element for a given load- carrying capacity. Structural material optimization can reduce the dead load which reduce the contribution of seismic effect in high rise structures and also very good at the vibration dampers and heat isolation. According to the natural behaviour of the concrete, it is strong in compression and weak in tension.
• Prestressed concrete is a modern material in which the stresses resulting from external loads are counteracted to a desired degree by introducing internal stresses of a suitable magnitude. • In reinforced concrete members, the prestress is commonly introduced by tensioning the steel reinforcement. • The apparent tensile strength of a material like concrete, which is strong in compression but weak in tension, is increased by application of permanent compressive stresses. • ¬¬¬¬Once the initial compression has been applied, the resulting material has the features of ductile high-strength steel when subject to tension forces and high-strength concrete when subjected to any compression forces. The tensile strength of the material increases because the subsequent application of tensile stress must nullify the compressive prestress.
Plastic shrinkage crack may not affect the strength of structure but will ruin the appearance of the structure and the crack to full depth may allow water to penetrate it. Figure 9. Plastic Shrinkage Crack Figure 9 is a representation of plastic shrinkage crack where crack propagation is highly evident. There are several ways to minimize this crack such as in hot weather, lower the temperature of the fresh concrete by using chilled mixing water or replacing some of this water with crushed ice. Covering the concreted area to avoid excess evaporation or proper curing can help reduce this crack formation.
Introduction The most important invention of the Romans was the invention of concrete, because it made a lot of other inventions possible. The Romans invented concrete by mixing pozzolana (which was a chocolate-colored volcanic material) and limestone. They then added strengthening materials like bricks and rocks. This mix was heated to a high enough temperature to make the substances fuse. The material would then be pulverized, with which you would get a powder.
One error that could have affected the percent yield is not filtering out all of the liquid from the filter paper in the funnel before setting it off to dry. This would have increased the final mass of the solid, not making it accurate. To stop this from happening again, the liquid could be drained more thoroughly until it fully stops dripping into the Erlenmeyer flask. Another error that could have affected the percent yield is the amount of trials performed. This would have made the results less accurate and made any errors change the final results even more.
Consequently, a new design has been done and fabricated by AM technology. Then, to reach a secure drilling a telesurgery system was employed. A new control algorithm was proposed to improve telesurgery system performance. To reach this goal a force estimation algorithm was employed to improve system transparency and eliminating force signals measurement directly. Finally, experimental results verify that pedicle screw placement has greater quality and accuracy, compared to the free-hand technique under fluoroscopy supervision.
It is used for two main intention; as a new construction wearing course and as a precautionary maintenance for an existing pavement. BST, or chip seal, comprising of a flake of asphalt binder that is superimposed by a flake of aggregate embedded in the binder that furnishes, into other things, conservancy to the existing stratum flake from tire blight and a skid resistance surface texture for vehicles. Sprayed seals is a low cost alternative compared to other pavement surfaces but the roadway has to be resurfaced more frequently because a severely distressed underlying stratum will minimize the attribute of the chip seal and shorten its service life. Chip seals, also called "stone-and-oil" or "sprayed seals" are bituminous stratum remedy containing of single-size aggregate dilation on a road just after sprinkle with asphalt emulsion. They are normally used to clog subgrade decay by sealing small rift in the stratum, thus stopping infraction of water, and also to reforming roadway skid counteraction and riding quality.
For this the mold should be made from high strength preferably of hardened steel. Secondly, for better mechanical properties it is advised that the molded items be annealed. Thirdly, mold release agents if required should only be made from fluorine based compounds to avoid stress cracks. Applications Poly (ether sulphone) has a variety of applications in a vast array of fields. The most successful applications are mentioned below.
The construction of the stacked flat laminates is carried out by a mould of rigid and flexible sides. This permits the selection of the mould that processes the laminate very rapidly, accurately and with minimum waste of raw materials. The manufacturing method would produce laminates of greater strength and design flexibility in comparison to the traditional methods such as the hand lay-up. Due to the potential problems that can arise with infusion moulding, a trial and error approach should be used to perfect the setup (Fibre-Glast, 2013). These potential problems are leaks occurring or air getting into the resin inlets, which can create air bubbles or the air could create locks which could lead to resin pooling the part.
Its thermal conductivity is 0.025 W/mK so very little heat is transferred through it. Which is needed as a building loses a lot of its heat through its walls. Polyurethane board also has a low moisture vapour permeability and a high resistance to water absorption stopping the water from being able to penetrate the walls and getting into the house reducing the chance of damp areas appearing. Different types of polyurethane board have different properties with some costing more than a normal board due to these properties. Some boards are able to contain fire resistant properties and others are denser making them stronger.
Water leaking through the concrete can carry dissolved salts that get deposited on the wall surface after the water has evaporated. Unlike white mold, the salt itself is harmless and is readily cleaned off. However, simply removing efflorescence does not solve the underlying problem which is the water leakage through the wall. The efflorescence will simply return over time as more leakage occurs, and as mentioned previously, the leakage can cause other serious problems. One exception is efflorescence resulting from the initial concrete placement.