Concrete Engineering

INTRODUCTION
Retaining walls are structures which are designed and constructed to resist lateral pressure of soil. When there appears a change in ground elevation that exceeds angle of repose of soil then these walls prove effective. These types of walls are used in construction of buildings having basements, bridges, roads, etc. when it is necessary to retain embankments or earth in a relatively vertical position. These are supported by rock or soil underlying the base slab or supported on piles. When these walls retain earth or any such material in earthen embankments for railways, roads, wing walls of bridges and many more, then such earth or any such material is referred to as backfill. In order to design such walls is mandatory to determine the pressure exerted by and acting on plane faces of soil. Retaining walls can be designed by Working Stress Method or Limit State Method. In both methods Rankine’s theory of earth pressure is used which consists of both passive earth pressure and active earth pressure. By finding stresses we can estimate and design these walls.
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Introduction
Curing is the process of providing moisture to the concrete mix so that better interlocking is established. If curing is not done properly then it will cause insufficient hydration and as a result there will be capillary pores, causing cracks and shrinkage. Moreover, strength and durability will also get affected and the concrete will disintegrate and break. It also ensures to maintain a sufficient temperature of concrete at its early age. It must be implemented as soon as placement & finishing is done. Also, it must continue for a specific period for the concrete to achieve its desired strength and durability. Uniform temperature is necessary to avoid thermal shrinkage cracks, plastic shrinkage and problems like bleeding and segregation.

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What is Concrete Discoloration?
A simple definition of concrete discoloration is a shift away from the original color. The presence of calcium chloride in the concrete, cement, and additives, as well as problems with curing, weather, and poor workmanship, could all play a role. These causes of discoloration can be mitigated to some extent. However, steps can be taken to mitigate the effects of dark patches, strips, and blotchy concrete that a contractor may experience. Once the concrete has fully cured, the appropriate treatment method can be chosen based on the root of the discoloration.

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What is Concrete Anchor?
An anchor is a piece of steel used to transfer loads to concrete. They can be cast into the concrete or put into a piece of hardened concrete later. There are several kinds of cast-in anchors, but headed bolts, hooked bolts (J- or L-bolts), and headed studs are the most common. The expansion anchor, the undercut anchor, and the sticky anchor are the three anchors used after the fact.

In adhesive anchors, steel parts like threaded rods and reinforcing bars that have been bent or internally threaded steel sleeves with bends on the outside are used. Anchor systems often join two structural parts or attach a non-structural part to a building.
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What is Concrete Retarder?

Retarders are additives that slow the setting of cement paste and, by extension, mixtures like mortar or concrete that contains cement. Concrete retarders are also known as retarding admixtures or just retarders. Adding a retarder to the concrete mix can delay the setting time by up to an hour. They slow the hardening process in warmer weather to give workers more time to mix, transport and place the concrete. Retarders not only slow down the process, but they also save water.
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What is Plum Concrete?
Plum concrete, also known as cyclopean concrete and rubble concrete, combines wet concrete and a plum (large size, strong, clean natural coarse aggregate or boulders of roughly 300 mm or larger). Plum makes up about 30–40% of the overall weight of the poured-in-place material.

U.S. technical specifications recommend a ratio of 60 percent plain concrete to 40 percent big stones when building with Cyclopean concrete. On day 28, the plain concrete used in this project must have a minimum resistance of 180 kg/cm2, and its ingredients must be thoroughly saturated before being mixed. The stone used must be in line with ASTM standards, and the blueprints will determine the exact dimensions for the foundation.

Plum’s presence in concrete lowers the required hydration heat since it eliminates the need for an excessive amount of cement while maintaining the material’s strength. Constructions of gravity dams, embankments, filling of deep or uneven terrain, foundations, etc., are all common applications for plum concrete. It’s a cheap replacement for regular cement.

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What is Transportation of Concrete?
Transportation of concrete is a way to move fresh concrete from where it is mixed to where it will likely be used in the structure. Since the time it takes to move concrete depends mostly on how long it takes to set up at first and how much workability is needed at the site, it should be a design parameter. The method of moving concrete is decided ahead of time so that the right additives can be added to improve certain properties.

Importance of Transporting Concrete:
The planning and execution of concrete transportation must be meticulous. For temporary jobs, thirty minutes of travel time is usually sufficient. Concrete should be unloaded from agitating transport equipment at a ready-mix plant or other central or mobile plants within two hours. This time is cut in half if the silent transport vehicles are utilized. To avoid honeycombing or chilly joints, you should not wait around. If you choose the wrong way to transport concrete, it could get mixed up and be useless. So, the right way must be chosen to move the concrete based on the needs. There are many things to think about when choosing how to transport concrete, such as:

• Type of concrete mix and its parts
• Conditions of the weather, like humidity, temperature, wind speed, etc.
• Size of building, Type of building
• Topography
• Position of the batching plant
• Price of transportation

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Recent advancements in construction technology have resulted in concretes that have almost surmounted these constraints and are close to optimal circumstances. Modifying the microstructure of the cement paste, inducing more air to make it lighter, allowing flexibility in reducing or raising the setting pace, and so on are some of the ways used to improve its qualities.Concrete’s versatility allows it to be used for a variety of applications. However, it has several disadvantages, including low tensile strength, reinforcement corrosion, and vulnerability to chemical attacks, all of which limit its endurance.

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What Grillage Foundation?
Grillage foundations are made of one, two, or more levels of beams (usual steel) superimposed on a layer of concrete to distribute load across a large area. It is found at the bottom of the columns. These layers are concrete-encased and at right angles to one another. This foundation form commonly supports heavy building columns, piers, and scaffolds.

Even though foundation and grillage appear to be the same, they are not. Grillage disperses huge loads across broad areas, similar to how foundations distribute the load from the structure to the ground.

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What is a Retaining Wall?
In technology, a retaining wall could be a significant reasonable construction. The first function of the wall is to keep the earth or other materials vertical or near-vertical. This wall is commonly used in various applications, including road, railway, bridge, irrigation engineering, land reclamation, and coastal engineering. The vertical or inclined stem is solid monolithically joined to a base block. These are considered suitable up to a height of 6 meters.

Retaining walls are solid wall structures that support soil laterally to keep the ground surface at distinct elevations on both sides of the building. If a retaining wall is not present, the soil at a higher elevation will tend to sink until it reaches its natural, stable shape.

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