one of the promising applications of Nano silica is to promote the hydration of cement blended with fly ash, slag or other pozzolanic materials(21; 7; 22). Some authors concluded that Nano silica can improve concrete workability and strength (23; 24; 25). Also others concluded that when NS (wt.%) is mixed into the cement mortar in the fresh state it has a direct influence on the water amount required in cement mixtures, for that higher amounts of water or chemical admixtures are needed to keep the workability of the mixture (26; 27; 16). 2.2.2. Influence of Nano silica addition on cement pastes, and mortars Hui Li et al.
The strength of concrete varies according to the proportions of its constituents. Concrete gains its strength over time as it hardens by means of setting, where by cement undergoes a chemical reaction known as hydration. It can set and harden underwater hence it can be used as foundation material. Its hardening process can be enhanced by curing. Due to its workability it can be formed into different
The highly fluid nature of SCC makes it suitable for placing in difficult conditions and in sections with congested reinforcement. Use of SCC can also help minimise hearing-related damages on the worksite that are induced by vibration of concrete. Another advantage of SCC is that the time required to place large sections is considerably reduced. SCC has an ultimate load bearing capacity under compression but the material is weak in tension. That is why steel bars are embedded in the concrete for the structures to carry tensile loads.
Essential Design Guidelines for Injection Mold Companies Injection molding is one of the most productive ways of plastic product manufacturing. Wide range of material availability and practical product designs increased the business of injection mold companies. More complex design modules became easier. While designing a mold structure, the designer should follow few guidelines. Blueprint of a Mold Manufacturer: The increasing demand for plastic parts and products is quite obvious in all industries.
Retarders do not actually decrease the ultimate compressive strength of the cement, but slows the rate at which the strength develops. The most commonly used retarders are natural lignosulfonates and sugars. The modern retarders are made from various synthetic compounds (Joel,
CHAPTER 3 Project Description 3.1 THEORITICAL CONCEPTS ABOUT FIBER REINFORCED CONCRETE Concrete being a brittle building material and having low tensile strength is unfit to resist tension until duly reinforced. The concept of using fibers to reinforce building materials is not a nascent concept this method has been old and been run by intuition. Hoarse hairs and straws had been used in old times to prevent plaster material from cracking. More recently when Portland cement started evolving, attempts were made to enhance the properties of the cement by adding fibers. The concept of adding fibers to overcome the inherent behavior of concrete of showing brittle failure under tensile load.
It allows fast replacing of cast in situ concrete to shape beams, walls, slabs and columns. It is preferred for the wall construction instead of columns and beams due to a lot of repetitive of the same wall components in building wall frame. Its components are widely available in standard sizes and stiffened using built in stiffeners or tie roads to tolerate the concrete pressure when concreting is being done. This system provides a rapid speed of installation, less cost and simplicity in instruments. It also gives excellent accuracy and good interior finishing which ends the need of
High rate of pouring might cause turbulence but slow rate of pouring might also cause the material to solidify even before the mold has been fully filled with the material (Bilal n.d). The pouring temperature, defined as the initial temperature of the material before it is poured into the mold, must be higher than the solidification temperature of the said material (Bilal n.d.) Fluidity, which is defined as the capability of the material to flow into the mold before solidification also affect the quality of cast products since it plays a key role in the ability of the material to completely fill the regions of the mold before the material solidifies. Some of the factors that affect fluidity include: temperature, material composition, heat transfer to the environment and
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.
Low post cracking capacity. 3. Brittleness and low ductility. The presence of micro cracks in the concrete play a significant role in decreasing the strength of plain concrete, this problem can be solved by adding different fibers in the mixture of the concrete, many kinds of concrete can be used one of them is steel fibers which we