Monday, 22 October 2012

Deep compaction technology

Deep compaction technology is used for ground improvement. This is a new technology and becoming popular. It has been observed that site improvement is generally cheaper than either excavation and replacement, or deep pile and other foundation systems that make it feasible to develop land with poor bearing capacity, high settlement and other undesirable characteristics. Ground improvement has following main objectives as given below:

1. Reduced settlement, particularly important for ground on which heavy structures or machinery will be erected.

2. Increased bearing capacity and/or stability.

3. Reduce pemeability.

4. Improved dynamic performance, especially resistance to liquefaction in earth quake prone regions, and in the case of ground under heavy machinery, resistance to vibration settlement.

Recent trends in tyre construction

In the field of civil engineering and construction, a lot of equipments are used. Some equipments are having tyre base. For that, we should also consider about the tyre of those equipments or machine such as JCB, during the construction.

Recent trends in tyre construction
Image Credit : Reza Estakhrian

Now a days, recent trends in tyre construction is large size tyres, use of extra tread, use of improved quality of rubber compounds to give a more tough and abrasion resistant tyre. More rubber by increasing thickness of undertread and of the sidewall to get more tyre life under sever conditions. Although this increase the cost of tyre, but reduces the cost per hour or per km of work due to more life.

Chemical classification of rocks

Chemically rocks are classified on the basis of chief constituent minerals.

Chemical classification of rocks
Image Credit : malcolm park

1. Argillaceous rocks :
Principal contituent is clay as in slate and laterite.

2. Silicious rocks :
Chief constituent is silica as in quartzite and granite.

3. Calcareous rock :
Chief constituent is lime. Lime stone and marble are its examples.

Physical classification of rocks

Physically rocks are classified as:

1. Stratified rock :
This shows distinct layers along which it can be easily split into thin slabs. Slate, sand stone and lime stone are its examples.

2. Unstratified rock :
This rock shows no sign of stratification and cannot be easily split into thin layers. Granite, basalt and trap are its examples.

All of sedimentary rocks are essentially stratified whereas all igneous rocks are unstratified. Metamorphic rocks may be either stratified or unstratified, depending upon the type of rock transformed.

Physical classification of rocks
Image Credit : Aaron McCoy

Rocks forming minerals in building stones

Rocks forming minerals
Image Credit : Joe Cornish

Quartz-Silica, Felspar-Alumina, Lime and Magnesia are mineral earths. Silica and the silicates form the largest class of rock forming minerals.

Silica is the most common mineral  generally found as quartz, sand and flint. Silica is very hard and durable and is unaffected by weathering agencies and forms about 60% of the constituent of common rocks and alumina forms about 15%.

Alumina is the chief constituent of clay. Quartz is pure silica and generally translucent with white wpaque color. It is also found in some other colors. Most of the common sand is a form of quartz.

Mica is a source of weakness in a stone. The stone having more than 2% of mica are unsuitable for structural purposes. Mica flakes are either white or dark brown or black and shine with metallic lustre.

Rocks forming minerals in building stones
Image Credit : Glow Decor

Derrick cranes

Derrick cranes consist of a mast, a boom, a bullwheel on which it rotates about a vertical axis, and supporting members (also known as guys). These cranes are very widely used in construction projects, industrial and multistoreyed building construction,  plant errection, loading and unloading of cargoes at ports, in ship building etc. When used with grabs it can handle loose materials like sand, ballast, coal etc.

Derrick cranes

You can see in the image the most of the derrick cranes are supported by a number of guys. The boom can revolve through 360 degree and can pass below these guys. A bullwheel is attanched to the mast and rotates it. These are operated by either a diesel engine or by an electric motor.

As mentioned above, mast is generally supported by guy ropes but when this is replaced by structure it becomes stiffleg derrick. In this case the mast is supported at its upper end by two braced stiffleg, therefore the boom rotates through angle of 270 degree to 290 degree.

The derrick cranes are sometimes mounted on rail wagons for quick transportation and for working near rail lines, and are known as whirler cranes. These cranes are available upto capacities of 40 tonnes with 25 meters boom length and 15 meter work radius.

The derrick cranes can be used as tower cranes for the purpose of errection of high industrial and residential builidings of height 100 meter or above. The derrick cranes are also designed to work as port tower cranes (for use in ports for container and general cargo handling), as shipyard cranes (for use in ship building and ship repairing works with longer capacities and larger working radii).

Some Importants Definitions

In the field of civil engineering technology, we always use various types of materials related to stones where sometime some confusable words or terms come with us that time, it's most important to have idea about all of those terms. Here, you can see some importants definitions of the terms which may help you to get rid of all of those problem. The definitions of the terms are given as below: 

1. Bedding plane:
The meeting planes of two adjacent layers in deposits of sedimentary origin is called bedding plane.

2. Fisured rock :
Broken or cracked rock is called fussured rock.

3. Fault :
It is a dislocation of continuity of rock strata as a result of cracking of the earth crust.

4. Rubble :
Natural irregular shaped but approximately cubical pieces of stones are called rubble.

5. Flag stone :
These stones are slabs of stones usually 2 cm to 5 cm thick. They are used for floorings or pavings.

6. Mineral :
It is a homogeneous matter of defiaite chemical composition and constant physical character. Earth's crust may be composed of a meneral or of an aggregate of mineral deposits.

7. Freestone :
It is a rock of even texture which can be ornamentally carved for buildings. It is also a rock which can be quarried by splitting easily along certain bedding planes.

8. Drift :
Boulder clay, sands and gravel etc., all superficial deposits of the earth's crust are called drift.

9. Diluvium :
Glacial deposits are called diluvium.

10. Eluvium :
Superficial deposits formed of fragmental material from solid deposits which have not been transported by wind or water but may have slipped down hill slopes under the action of gravity.

11. Crow foots :
There are veins containing dark colored uncemented materials.

12. Bed rocks :
Any hard rock bed underlying soft deposits is called bed rocks.

13. Quoins :
The corner stone having two of its faces made plane.