Learn free Civil Engineering by Civilustaad about SOIL MIXING

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SOIL MIXING

Deep soil mixing is an in situ ground improvement method that enhances the characteristics of weak soils by mechanically mixing them with a cementitious binder. The action of mixing materials such as cement, lime or bentonite, fly ash with soil causes the properties of the soil to become extra like soft rock.

DSML provides two types of deep soil mixing for geotechnical and environmental applications, including mass mixing, and column mixing. 

Both systems present wet and dry soil mixing solutions, which enable the additives to be placed as wet slurry or dry powder. 

They are able to tackle some of the most hard soil conditions, ranging from flood plains and soft soils through to contaminated land.

Learn free Civil Engineering by Civilustaad about SOIL CLASSIFICATION

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SOIL CLASSIFICATION

The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to explain the texture and grain size of a soil. 

The classification structure can be applied to most unconsolidated materials, and is represented by a two-letter symbol. Each letter is described underneath (with the exception of Pt):

If the soil has 5–12% by weight of fines passing a #200 sieve (5% < P#200 < 12%), both grain size distribution and plasticity have a major effect on the engineering properties of the soil, and dual notation may be used for the group symbol.

 For example, GW-GM corresponds to "well-graded gravel with silt."

If the soil has more than 15% by weight retained on a #4 sieve (R#4 > 15%), there is a considerable amount of gravel, and the suffix "with gravel" may be added to the group name, but the group symbol does not change.

For example, SP-SM could submit to "poorly graded SAND with silt" or "poorly graded SAND with silt and gravel."

Learn free Civil Engineering by Civilustaad about SPIRAL CURVES

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SPIRAL CURVES

Spiral curves were initially designed for the Railroads to smooth the transition from a tangent line into simple curves. They helped to lessen the wear and tear on the tracks. Spiral curves were implemented at a soon date on highways to provide a smooth transition from the tangent line into simple curves. 

The highway engineers later determined that the majority drivers will naturally make that spiral transition with the vehicle; consequently, spiral curves are only used on highways in special cases nowadays.

Because they were used in the past and in particular cases today, we need to identify how to calculate them.

From the surveyor’s viewpoint, the design of spiral curves has previously been determined by the engineer and will be documented on existing R/W and As-built plans. 

All we have to do issue, the information shown on these plans to fit the spiral curve inside our surveyed alignment

Learn free Civil Engineering by Civilustaad about SHOTCRETE

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SHOTCRETE

Shotcrete is, in effect, an edition of a cast-in-place concrete wall. Rather than placing concrete into forms, nevertheless, a fresh mix is sprayed onto wall panels that have been erected in the form of the building. 

A nozzle-man applies concrete from a pressurized hose to include the reinforcement and build up the wall thickness, forming structural shapes that include walls, roofs, floors, and other assemblies. 

This material has also been called “gunite” in reference to the nozzle or “gun” used to shoot matter at the form face. 

Any surface appropriate for accepting fresh concrete can be used: steel, wood, and polystyrene are common. 

Finishes are frequently applied directly to the concrete while it is still wet.

Learn free Civil Engineering by Civilustaad about SHEET PILES info

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SHEET PILES INFO

Sheet piling is an earth retention and excavation support method that retains soil, using steel sheet sections with interlocking edges. Sheet piles are installed in chain to design depth along the planned excavation perimeter or seawall alignment. The interlocked sheet piles form a wall for permanent or temporary lateral earth support with reduced groundwater inflow. Anchors can be integrated to provide additional lateral support if required.

Sheet pile walls have been used to carry excavations for below grade parking structures, pump houses, basements and foundations, construct cofferdams, and to build seawalls and bulkheads. Permanent steel sheet piles are designed to give a long service life.

Vibratory hammers are used to install sheet piles. If soils are too hard or dense, an impact hammer can be used to complete the installation. 

At assured sites where vibrations are a apprehension, the sheets can be hydraulically pushed into the ground.

Sheet piles are too a sustainable alternative since recycled steel is used in their construction, and the piles can often be reused.

Learn free Civil Engineering by Civilustaad about SHEAR WALL CONSTRUCTION

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SHEAR WALL CONSTRUCTION

Shear wall, in building construction, a rigid vertical diaphragm capable of transferring lateral forces from floors, exterior walls, and roofs to the ground foundation in a direction parallel to their planes. 

Examples are the reinforced-concrete wall or vertical truss. 

Lateral forces caused by earthquake, wind, and uneven settlement loads, in addition to the weight of structure and occupants; generate powerful twisting (torsional) forces. 

These forces can factually tear (shear) a building apart. Reinforcing a frame by attaching or placing a rigid wall inside it maintains the shape of the frame and avoids rotation at the joints. 

Shear walls are particularly important in high-rise buildings subject to lateral wind and seismic forces.

Learn free Civil Engineering by Civilustaad about SELF COMPACTING CONCRETE

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SELF COMPACTING CONCRETE

Self-compacting concrete (SCC) is considered by several experts to be the greatest breakthrough in concrete technology for many decades due to the enhanced performance and working environment. 

It all started around 1988 at Tokyo University with Prof. Okamura and his students, among others Ozawa and Maekawa, as they established the fundamental description of SCC. 

Before that, numerous cases of application were known in which the concrete did not need external consolidation to obtain essential compaction and could consequently be considered as SCC, without being defined as such.

Learn free Civil Engineering by Civilustaad about REINFORCED STRIP FOUNDATION

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REINFORCED STRIP FOUNDATION

There are several types of foundation. Differing ground conditions, backfilled land, soil types, proximity of trees, proximity of drains, wind speeds, all dictate the form our foundation work will take. 

This project will deal only with the strip foundation, the most common and extensively used. 

Sign will be given here where strip foundations may not be appropriate. 

A strip foundation is fairly simply a strip of concrete placed in a trench. 

The absolute minimum thickness of this strip is 150mm.

Learn free Civil Engineering by Civilustaad about RAINWATER HARVESTING TANKS

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RAINWATER HARVESTING TANKS

Rainwater harvesting is a technique of collection and storage of rainwater into natural reservoirs or tanks, or the infiltration of surface water into subsurface aquifers (before it is lost as surface runoff). One method of rainwater harvesting is rooftop harvesting. 

With rooftop harvesting, mainly any surface — tiles, plastics, metal sheets, but not grass or palm leaf — can be used to intercept the flow of rainwater and give a household with high-quality drinking water and year-round storage. Other uses comprise water for livestock, gardens, and irrigation, etc.

The reasons for using rainwater harvesting systems answer three questions:

What: Rainwater harvesting will develop water supply, food production, and finally food security.

How: Since rainwater harvesting leads to water supply which leads to food security, this will significantly contribute to income generation.

Who: Water insecure households or individuals in rural areas will advantage the most from rainwater harvesting systems.

Learn free Civil Engineering by Civilustaad about PUNCHING SHEAR REINFORCEMENT

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PUNCHING SHEAR REINFORCEMENT

As a cost-saving construction method, flat slabs are extensively used in concrete construction because in addition to only a tiny amount of formwork, they also provide optimum space utilization. The use of punching shear reinforcement in columns enables thin slabs all the way through because it absorbs very high shear forces. Rapid construction progress is guaranteed as well as the essential high level of installation safety. For the installation of punching shear reinforcement, different versions are existing for in-situ concrete and prefabricated slabs: 

Setting up of the punching shear reinforcement from below: shear reinforcement and spacers are positioned directly on the formwork; lower and upper steel reinforcement is mounted by the bolt heads;

Setting up of the punching shear reinforcement and spacer between the welded wire mashes by installing the shear reinforcement after the lower reinforcement layers are positioned;

Setting up of the shear reinforcement from above, i.e. following the installation of the lower and upper reinforcement layers.

Learn free Civil Engineering by Civilustaad about PILE CAP

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PILE CAP

Loads from columns transferring to pile cap bring tensile forces at the bottom of the cap. For example, by using truss analogy to investigate a pile cap sitting on two piles with a column at the centre of the pile cap, the tensile force at the bottom is proportional to the pile spacing and is inversely proportional to depth of pile cap. The bottom reinforcement is calculated to resist the tensile stressed generated from loads in columns. 

Side reinforcement may not be essential in pile cap (L.A. Clark (1983)). In fact, the prime aim of the side reinforcement is to control cracking. 

Nevertheless, as most pile caps are hidden from view and it is considered not necessary to give side reinforcement to pile caps based on aesthetic reason.

Occasionally, reinforcement may be calculated at the top of pile caps which serve as compression reinforcement. 

This kind of reinforcement is required in case there is a limitation on the depth of pile caps. Likewise shear reinforcement is introduced to the pile caps in case there is a restriction to the depth of pile caps.