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Latest Construction News

Construction workers compete on their skills
A sea of white hard hats spread across the crowd, but it wasn't a construction site. It was the entire ground floor of The Greater Fort Lauderdale/Broward County Convention Center. Except for the hum of machines, all was quiet Thursday as more than 200 …
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Reason behind rising construction costs
MASON CITY, Iowa – Skilled workers are needed in Iowa and Minnesota, so much so that the lack of labor is starting to reflect in the market. Construction costs are up, and it's not due to the cost materials. One good example of this is the proposed …
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Sri Lanka Halts Chinese-Backed Construction Project
COLOMBO, Sri Lanka—Sri Lanka's new government Thursday ordered a halt to work on a massive Chinese-backed construction project as it weighs the legality of the undertaking and reassesses the country's commercial ties with Beijing. After a review board …
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Windsor picks Pinkard Construction to expand rec center
Pinkard Construction will be the company adding a leisure pool, fitness studio and auxiliary gym to Windsor's Community Recreation Center. The Lakewood-based company was selected as the general contractor for the town's CRC expansion project.
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Highway Construction

The operations that are carried out for constructing an embankment are clearing, stripping and storing top soil, placing of embankment, rolling and finishing.

EARTHWORK

The process of earthworks is to excavate the existing land to a suitable level so that road construction may begin. The earthworks can take the form of either excavation in the form of cuts or the construction of embankments to carry an elevated highway. Excavation increases the volume of material. It is therefore necessary to use a bulking factor to determine the volume of material that will be created by excavation.

 Bulking factor is defined as:

Bulking Factor = Volume after Excavation/Volume before Excavation.

Similarly a shrinkage factor is defined for the compaction of a soil at its final destination:

Shrinkage Factor = Volume after Compaction/Volume before Excavation.

PRINCIPAL EARTHMOVING EQUIPMENT AND THEIR AREAS OF APPLICATION

Bulldozer – This is used primarily for pushing soil. Vehicles are generally tracked and require large amounts of traction.

Drag Line – This vehicle allows excavation below its own level. It is essentially a bucket on the end of a jib and is used solely for bulk excavation as it is relatively uncontrolled.

Dump Truck – These are wheeled vehicles and as such are able to move much faster. But due to offset by a lack of traction, dump trucks are always the first to get stuck.

Shovels – These are normally wheeled vehicles and are used to fill up the dump trucks. Typically they take 2-3 loads to fill an average dump truck.

Hydraulic Excavators – These can be either wheeled or tracked and are used again to excavate below truck level. They have a very small capacity and are extremely flexible.

Grader – Graders are used to level out deposited fill, ready for compaction.

Rollers – There are many different types of roller and they are used for compaction. Different types include vibratory, sheepsfoot and grid.

HIGHWAY PAVEMENTS

The road pavement is the actual surface on which the vehicles will travel. Its purpose is twofold, to provide friction for the vehicles and to transfer normal stresses to the underlying soil.

CLASSIFICATION

Pavements are classified according to their structural behavior into-

-Flexible pavement

-Rigid pavement

WEARING COURSE- It is the top layer of the road pavement and as such is (usually, but not always) designed to be impervious to the ingress of water. It should have an even running surface, durable, and a high resistance to skidding.
BASE COURSE-This is the layer of material below the wearing course and above the roadbase. The basecourse is a load spreading layer, spreading the load imposed on the wearing course over a wider area of the roadbase. 

ROADBASE-The roadbase is the main load-bearing / load spreading layer in the road structure and is usually 100mm or thicker depending on the loading of the traffic for which the road is designed. The roadbase is usually a bituminous material or hot rolled asphalt.

GRANULAR SUB-BASE-Granular sub-base is usually the material used in the sub-base layer, but materials other than granular sub base can be used in the sub-base layer. Granular sub-base (gsb) – is a graded granular material, usually a “hard rock”. SUBGRADE-The subgrade is the layer of naturally occurring material the road is built upon, or it can refer to the imported fill material that has been used to create an embankment upon which the road pavement is constructed.
EARTHEN ROADS

The pavement is constructed entirely with soil present at site. The camber provided is steep ranging from1 in 20 to 1 in23 which allows water to drain off quickly. The width of an earthen road is taken from outside to outside of shoulders, i.e. carriage plus two shoulders. A width of 6 m is sufficient but that of 7.5 is desirable. The side drains are provided to carry the rain water to a stream.

SOIL STABILISED ROADS

Earthen roads can be upgraded by stabilizing the soil which can be used as a base course or sub-base course. Soil stabilization increases the bearing power of soil by adopting controlled compaction, proportioning, and addition of admixtures or stabilizers.

WATER BOUND MACADAM

General- The W.B.M consists of clean crushed coarse aggregates which are mechanically interlocked by rolling and the voids in the aggregates are filled with screening and binding materials with the help of water. This is laid on a prepared sub-grade, sub-base or base or on an existing pavement. It can be used as a sub-base, base course or surfacing coarse.
Materials

-Crushed or broken stone, over burnt broken brick, kankar and laterite.

-Screenings.

-Binding Material.

CONSTRUCTION PROCEDURE OF W.B.M:-

(I) Preparation of foundation for receiving the Water Bound Macadam coarse.

(ii) Provision of lateral confinement of aggregate.

(iii) Spreading coarse aggregate.

(iv) Rolling.

(v) Application of screening.

(vi) Sprinkling and grouting.

(vii) Application of binding material.

PENETRATION MACADAM

It consists of one or more courses of crushed aggregate which are bonded and keyed by bituminous materials and filling aggregate. A seat coat is applied on top, if required. The thickness of each course should not exceed 75mm.

Materials Used:-The coarse aggregate consists of crushed stone and crushed gravel, and should be clean, strong, durable and fairly cubical in shape. It should be free from salt and dust. The crushed stone should be graded from 63 to 2.36mm. The key aggregate should also be graded from 38 to 2.36mm.

Construction:-The following are the stages in construction-

-Preparation of Base.

-Spreading and Compacting Coarse Aggregate.

-Rolling.

-Application of Bituminous Material.

-Application of Key Aggregates.

-Application of Seal Coat.

-Finishing.

CEMENT CONCRETE PAVEMENT-

  General-Cement concrete pavements are used on important highways.

Material

  Cement:-Ordinary Portland cement and high strength Portland cement are most widely used. However if the road is required to open at an earlier date, rapid hardening Portland cement is used.

Aggregate:-Aggregate should comply with specifications laid down in IS: 383-1970. The Los Angeles abrasion test value should not be greater than 35% and 50% for wearing course and subsurface course.

The coarse aggregate should be graded such that the aggregate is collected in two size ranges. If the grading is from 5-88mm then, one range will be below 20mm and other above 20mm.

Fine Aggregate:-Fine aggregate should be preferably natural. Sometimes crushed stone sand may also be used together with natural sand.

CONSTRUCTION

Proportioning of concrete – The mix required is designed in the laboratory so that the minimum structural strength in the field is achieved. The mix is proportioned so that a minimum flexural strength of 4 N/mm2 is developed in the field.

The following stages are involved in the construction of cement concrete pavement:-

1. Preparation of sub-grade and sub-base.

2. Placing of forms.

3. Batching of materials and mixing.

4. Transportation and placing of concrete.

5. Compacting and finishing.

6. Curing.

7. Removal of forms.

JOINTS IN CEMENT CONCRETE PAVEMENTS

Changes in temperature cause expansion or contraction in cement concrete pavements. Hence joints are provided in slabs to break the continuity and save it from getting damaged. There are three types of joints:-

-Expansion Joint

-Contraction Joint

-Warping Joint

SEALING OF JOINTS

After curing period is over and before the pavement is opened to traffic, the temporary seal and other materials in the joints should be removed completely and the grooves filled with approved joint sealing compound.

The edges of the joints should be first primed with primer, generally a thin bituminous paint, which should be allowed to dry before the sealing compound is applied.

The line of separation between adjacent slabs of concrete is cleaned and painted with 200 penetration grade bitumen.

REINFORCEMENT IN CEMENT CONCRETE PAVEMENT

Cement concrete pavement cracks when subjected to changes in temperature and moisture. Hence, reinforcement is provided not to increase flexural strength but to withstand the tensile stresses caused due to shrinkage and contraction. When the slab is provided with joints spaced properly to control cracking, reinforcement is not essential at all. The reinforcement consists of welded wire fabric or mats formed by small diameter bars.

Since the cracks due to high tensile stresses start at the top and tend to open, the reinforcement is preferably placed 50mm below the surface.

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Construction Technology

Construction is the term used in almost every other aspect of life. Construction basically signifies creation and building up of something. Not everyone can be a successful constructor; it requires a great deal of knowledge and patience to master the art of construction. For Construction of residential structures services of a good civil engineer who has a good knowledge of mechanics and various other geotechnical features related to land is essential. The advent of technology has surely helped the working of civil engineers to produce good and stable structures.

Since the dawn of era for computer aided designing in engineering has begun, new Construction technologies and mega structures have reached altogether new heights. One of the few marvels of Construction Technology is the Construction of Pre-engineered metal buildings.

Pre-engineered metal buildings are the Construction structure representing today’s new world. Pre-engineered metal buildings are easy to construct and preferable because they consume less time, money and labor power.  There are various forms in which these structures can be constructed; few of the design include deck sections which are produced by the mezzanine floor manufacturing company. For the implementation of the design various required parts of steel are made in bulk which can be reassembled at a later point of time to create a Pre-engineered metal structure. The assembling of the spare structure to create a magnificent structure depends on the creativity and brilliance of the architect.

These blocks can be put to a wide variety of uses. From warehouse building Construction to erecting multi story commercial complex, Pre-engineered metal buildings have carved a niche for them which defines style, creativity and durability altogether. They leave a scope of customization for the buyers. Moreover, the mezzanine floors manufacturers ensure that it is easy to relocate or dismantle a particular structure, failing which a Pre-engineered structure may not serve its full purpose.

A Pre-engineered steel building can either be a full-fledged Construction or can be a storage or roofing system. This enables the buyer to choose what is best suited to his needs. These structures when efficiently designed not only save time, but can also make the weight of a building lighter by about 30 percent which in turn means cost effectiveness as lesser steel has to be used.

Moreover, Pre-engineered metal buildings are designed on computers and ensure a better and a more contemporary design that changes the look of your building. This cannot be achieved by using bricks stuck in concrete. They can even be modified with time without bothering the other parts of a building. The traditional style was not dynamic enough to meet the needs of the industry. It did not leave much scope for modifications and has become obsolete.
Pre-engineered structures are modern and contemporary. They mark a new era in engineering and construction.

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Construction Aggregates

Aggregate industry products are commonly used in making asphalt pavements for transportation purposes or in nuclear family homes or even in business houses. Our water treatment plants or sewer treatment plants are constructed with concrete and aggregate that is used as a filter in both these plants.
 
How are Aggregate products produced?  

The process of stone quarrying involves breaking of stones into diverse shapes and sizes for building purposes. Quarry stone is used in all types of stone creations like the ones ranging from central offices to farm credit foundations. Most easily available natural resources and chief raw materials like sand and gravel are used mostly by the construction industry. After being mined from naturally occurring open deposits, they are then moved for processing. Processing includes: crushing of the material, handling of the material, screening, milling, dust collection, size reduction, conveying, loading or unloading.
The production of aggregate products results in dust emission, which is common to all these operations. “Fugitive Dust” is the term commonly used to describe such emissions. This means that the dust is coming directly from the process to air such as from open screens, conveyors or unpaved roads.

Why is DEC permit required?

All the equipments that are required in processing at quarry stone or sand and gravel mines and have a maximum rated capacity more than 25 tons of minerals per hour, require Department of Environmental Conservation (DEC) permit. Mobile crushers with maximum rated capacities more than 150 tons per hour for non-metallic minerals’ processing operations, like quarry stone, sand and gravel also require DEC permit. Exemption is granted for equipments installed before Aug 31, 1983 used for operations like wet conveying, washing and separating.

Online resources for reference:

For the best advice, you can refer to a reliable online resource to get information on crushed stone, sand & gravel operators, processing equipment manufacturers and people who deal in this process, service providers, and suppliers to the aggregates industry.

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Latest Construction News

US Construction Spending Rose 0.4 Percent in December
U.S. construction spending accelerated in December as building activity increased for new houses and government-backed highways. The Commerce Department said Monday that construction spending rose 0.4 percent in December. Total construction …
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I-4 ultimate makeover officially begins Sunday
At least six years of construction officially began 12:01 a.m. Sunday on Interstate 4. But commuters don't need to worry just yet: It will be a few weeks before they have to deal with mind-numbing congestion. The moment the clock turned to Sunday is …
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Where are the Chicago-area construction projects in 2015?
That's because in northeastern Illinois, construction season runs most of the year, put on hold only by "Chiberia"-like conditions or strikes involving lightning or labor unions. The relatively few freeze-and-thaw cycles so far this winter have …
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Metal in Construction

Been to cover iron structures with a protective coating. The term coating maybe taken as a reference to paint, but it is really much broader than that. Whatis reinforced concrete, for example, but steel with a very thick and brittlecoating Because concrete is brittle, it tends to crack and expose the steelreinforcing bars to corrosion. One of the functions served by prestressing orposttensioning is to apply a compressive force to the concrete in order to keepthese cracks from opening.

While one approach has been to apply coatings to prevent metal fromrusting, another has been to develop metals that inherently don’t rust. Rustmay be roughly dened as that dull reddish-brown stuff that shiny steel becomesas it oxidizes. Thus, the designation of ‘‘stainless” to those iron-basedmetals that have sufcient chromium content to prohibit rusting of the basemetal in atmospheric service. The ‘‘stain” that is presented is the rust stain.Stainless steel must have been a term that originated in someone’s marketingdepartment. The term confers a quality of having all the positive attributes ofsteel but none of the drawbacks.

If we were to apply a similar marketing strategy to aluminum, we mightcall it ‘‘light stainless steel.” After all, it prevents the rust stain as surely asstainless steel does, and it weighs only about one-third as much. Engineerswho regard aluminum as an alien material may be more favorably disposedtoward ‘‘light stainless steel.”For the past century and a half, then, structural engineers have relied onmetals to impart tension-carrying capability to structural components. Technicaldevelopment during that time has included improvement in the propertiesof the metals available for construction. One of the tasks of designersis to determine which metal best suits a given application.

While one approach has been to apply coatings to prevent metal fromrusting, another has been to develop metals that inherently don’t rust. Rustmay be roughly dened as that dull reddish-brown stuff that shiny steel becomesas it oxidizes. Thus, the designation of ‘‘stainless” to those iron-basedmetals that have sufcient chromium content to prohibit rusting of the basemetal in atmospheric service. The ‘‘stain” that is presented is the rust stain.Stainless steel must have been a term that originated in someone’s marketingdepartment. The term confers a quality of having all the positive attributes ofsteel but none of the drawbacks.

If we were to apply a similar marketing strategy to aluminum, we mightcall it ‘‘light stainless steel.” After all, it prevents the rust stain as surely asstainless steel does, and it weighs only about one-third as much. Engineerswho regard aluminum as an alien material may be more favorably disposedtoward ‘‘light stainless steel.”For the past century and a half, then, structural engineers have relied onmetals to impart tension-carrying capability to structural components. Technicaldevelopment during that time has included improvement in the propertiesof the metals available for construction. One of the tasks of designersis to determine which metal best suits a given application.

 

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Fault Tree Construction

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The accident data presented in this section are predominantly gathered from the Marine Accident Investigation Branch (MAIB). The MAIB is a totally independent unit within the Department of the Environment Transport and the Regions (DETR) and reports directly to theSecretary of State. The MAIB received 1,418 accident and incident reports in 1999.Accidents to ships accounted for 641 of those reports.

The data presented here is collected from 1992 to 1999 and reflects all the reported incidents and accidents relating to fishing vessels. It is thought that the actual accident andincident figures are higher than what is presented here, as many accidents are not reported to the coastguard authorities.

Figure 2.1 shows the total number of vessels lost (primary y-axis) and total number of vessels registered (secondary y-axis) from 1992 to 1999. These figures include all vessel sizesranging from under 12 meter to over 24 meter. From this graph, it is evident that the percentage of vessels lost increased from 1992 to 1994 and then reduced from 1994 to 1998.

From 1998 onwards, it is noted that there was a sharp increase in the percentage of vessels lost. Overall, the percentage of vessels lost was between 0.27% (minimum in 1997/98) and 0.45% (maximum in 1999) of the total registered vessels, as seen in Figure 2.2 There were approximately 7,460 UK-registered fishing vessels in 1999 (end December 1999 figure). During the year 370 accidents and incidents involving these vessels were reported to the MAIB. 33 fishing vessels were lost which at 0.45% of the total fleet represent the highest rate since 1994. Machinery damage is noted as the main contributor to the high number of accidents as seen in the pie chart of Figure 2.3.

An analysis of the data from previous years shows that machinery damage has contributed to
over 50% of all accidents. This could be attributed to several factors including poorly
maintained equipment, incorrect operation, age, lack of automation, etc. The graph in Figure
2.4 shows the number of accidents caused by machinery damage from 1994 to 1999.

Although the figures indicate a decreasing trend, the number of accidents related to this category is still high and certainly unacceptable from a safety perspective. The next highest contributor to accidents is found to be flooding and foundering followed by grounding and then collision and contact. A comparison of all accident types is made asseen in Figure 2.5. Flooding and foundering is estimated to cause almost 15% to 20% of accidents on fishing vessels.

These data are cumulated and presented as a pie chart in Figure 2.6 to reveal the contribution of each accident type for the sampling period. As revealed earlier, machinerydamage is found to be the most common cause of accidents on fishing vessels, contributing 64.4% of all accidents. Foundering and flooding (14.2%), grounding (10.2%),collision and contacts (5.7%), and fires and explosions (2.9%) follow. To determine the severity of the accidents on fishing vessels, data reflecting the accidents to vessel crew together with the number of deaths are gathered and presented in Figures 2.7 and 2.8.

These bar charts show that almost 30% of accidents to crew on vessels that are under 12 meter result in deaths and for vessels that are 12-24 meters and more than 24 meters in length, these figures are calculated to be 13% and 15%, respectively. The results indicate that vessels under 12 meters have the highest casualty rates and suffer severe consequences when an accident happens. This could be attributed to the size and stability of these vessels when sailing in bad weather conditions.

The number of under 12 meter vessels that were lost is much higher than the other vessels as seen in Figure 2.9. The trend in the number of vessels lost is difficult to determine, as it does not follow any specific mathematical rule. However, by comparing the graphs in Figures 2.1, 2.2 and 2.9, it can be concluded that from 1997, the number of vessels lost increased as the percentage of registered vessels decreased.

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