Friday, 27 February 2009
Tuesday, 24 February 2009
Flux-cored arc welding
Flux-cored arc welding (FCAW) is a semi-automatic or automatic arc welding process. FCAW requires a continuously-fed consumable tubular electrode containing a flux and a constant-voltage or, less commonly, a constant-current welding power supply. An externally supplied shielding gas is sometimes used, but often the flux itself is relied upon to generate the necessary protection from the atmosphere. The process is widely used in construction because of its high welding speed and portability.
FCAW was first developed in the early 1950s as an alternative to shielded metal arc welding (SMAW). The advantage of FCAW over SMAW is that the use of the stick electrodes used in SMAW is unnecessary. This helped FCAW to overcome many of the restrictions associated with SMAW.
Two Types of FCAW
One type of FCAW requires no shielding gas. This is made possible by the flux core in the tubular consumable electrode. However, this core contains more than just flux, it also contains various ingredients that when exposed to the high temperatures of welding generate a shielding gas for protecting the arc. This type of FCAW is attractive because it is portable and generally has good penetration into the base metal. Also, windy conditions need not be considered. Some disadvantages are that this process can produce excessive, noxious smoke (making it difficult to see the weld pool); under some conditions it can produce welds with inferior mechanical properties; the slag is often difficult and time-consuming to remove; and operator skill can be a major factor.
Another type of FCAW uses a shielding gas that must be supplied by an external supply. This is known informally as "dual shield" welding. This type of FCAW was developed primarily for welding structural steels. In fact, since it uses both a flux-cored electrode and an external shielding gas, one might say that it is a combination of gas metal (GMAW) and flux-cored arc welding (FCAW). This particular style of FCAW is preferable for welding thicker and out-of-position metals. The slag created by the flux is also easy to remove. The main advantages of this process is that in a closed shop environment, it generally produces welds of better and more consistent mechanical properties, with fewer weld defects than either the SMAW or GMAW processes. In practice it also allows a higher production rate, since the operator does not not need to stop periodically to fetch a new electrode, as is the case in SMAW. However, like GMAW, it cannot be used in a windy environment as the loss of the shielding gas from air flow will produce visible porosity (small craters) on the surface of the weld.
One type of FCAW requires no shielding gas. This is made possible by the flux core in the tubular consumable electrode. However, this core contains more than just flux, it also contains various ingredients that when exposed to the high temperatures of welding generate a shielding gas for protecting the arc. This type of FCAW is attractive because it is portable and generally has good penetration into the base metal. Also, windy conditions need not be considered. Some disadvantages are that this process can produce excessive, noxious smoke (making it difficult to see the weld pool); under some conditions it can produce welds with inferior mechanical properties; the slag is often difficult and time-consuming to remove; and operator skill can be a major factor.
Another type of FCAW uses a shielding gas that must be supplied by an external supply. This is known informally as "dual shield" welding. This type of FCAW was developed primarily for welding structural steels. In fact, since it uses both a flux-cored electrode and an external shielding gas, one might say that it is a combination of gas metal (GMAW) and flux-cored arc welding (FCAW). This particular style of FCAW is preferable for welding thicker and out-of-position metals. The slag created by the flux is also easy to remove. The main advantages of this process is that in a closed shop environment, it generally produces welds of better and more consistent mechanical properties, with fewer weld defects than either the SMAW or GMAW processes. In practice it also allows a higher production rate, since the operator does not not need to stop periodically to fetch a new electrode, as is the case in SMAW. However, like GMAW, it cannot be used in a windy environment as the loss of the shielding gas from air flow will produce visible porosity (small craters) on the surface of the weld.
FCAW key process variables
Wire feed speed (and current)
Arc voltage
Electrode extension
Travel speed
Electrode angles
Electrode wire type
Shielding gas composition (if required) Note: FCAW wires that don't require a shielding gas commonly emit fumes that are extremely toxic; these require adequate ventilation or the use of a sealed mask that will provide the welder with fresh air.
Travel Angle.
FCAW advantages and applications
FCAW may be an "all-position" process with the right filler metals (the consumable electrode)
No shielding gas needed making it suitable for outdoor welding and/or windy conditions
A high-deposition rate process (speed at which the filler metal is applied) in the 1G/1F/2F
Some "high-speed" (e.g., automotive applications)
Less precleaning of metal required
Metallurgical benefits from the flux such as the weld metal being protected initially from external factors until the flux is chipped away
Low operator skill is required
Wire feed speed (and current)
Arc voltage
Electrode extension
Travel speed
Electrode angles
Electrode wire type
Shielding gas composition (if required) Note: FCAW wires that don't require a shielding gas commonly emit fumes that are extremely toxic; these require adequate ventilation or the use of a sealed mask that will provide the welder with fresh air.
Travel Angle.
FCAW advantages and applications
FCAW may be an "all-position" process with the right filler metals (the consumable electrode)
No shielding gas needed making it suitable for outdoor welding and/or windy conditions
A high-deposition rate process (speed at which the filler metal is applied) in the 1G/1F/2F
Some "high-speed" (e.g., automotive applications)
Less precleaning of metal required
Metallurgical benefits from the flux such as the weld metal being protected initially from external factors until the flux is chipped away
Low operator skill is required
Welding defects
What are Welding-defects?
They are excessive conditions, outside the acceptance limits, which risks to compromise the stability or the functionality of the welded structure. They are also called rejectable discontinuities. This means that the same type of discontinuity of a lesser degree, might be considered harmless and acceptable.
Are there acceptable Welding-defects? No, by definition a defect is rejectable. There can be acceptable discontinuities. The designer, or the purchaser, or the person in charge of the welding project is entitled to define the limits of acceptance. And these limits are valid only for the application and the usage involved.
Are there undetected defects? Hopefully not! No Welding-defects should go undetected, but undetectable discontinuities yes, that are acceptable, as defined by the designer.
What should be done when Welding-defects are detected? One should reject the items and put them temporarily on hold. One should determine the cause and try to implement a corrective action to avoid future recurrence. Then an authorized professional should determine if the defects are repairable or not. If yes by which procedure. Standard procedures may be approved for routine application.
What is the difference between discontinuities and Welding-defects?
A discontinuity is an objective lack of material, an interruption in the physical consistence of a part. Examples are cracks, seams, laps, porosity or inclusions. It may or may not be considered a defect depending if it its presence endangers or not the integrity, the usefulness and the serviceability of the structure.
By knowing what is likely to produce Welding-defects one should learn how to avoid them. It is essential to distinguish discontinuities from harmful defects. Production without defects saves worktime, materials, repair costs, decrease in productivity. Excessive defect production indicates some basic condition affecting the operation which should be investigated and corrected.
Causes for rejection and how to avoid Welding-defects.
Avoidance of Welding-defects starts with correct design and preparation. This may look as an obvious statement but somehow it is a more frequent than desired situation. There is no point in trying to correct by welding for misalignment or for improper set up of the workpiece. There is no gain in time, really, only an increased probability of producing Welding-defects and of spending time and resources in trying to repair the welded item.
Also the use of recommended tools and fixtures should be implemented with no excuses admitted for temporary unavailability. The required means, in good operational condition, should be used with the correct parameters, according to the approved procedure. If the welding procedure is incapable of ensuring defect free implementation, then it should be improved upon.
The welder or the machine operator should be proficient in the process selected and all physical accessories assigned should be ready for use. Among them, aspirators of fumes, fan to circulate air, screens to protect other workers nearby, etc.
If electrodes need be dried, so they should be. Cleaning of fixtures and workpiece should be performed before setting up. A last touch up may be repeated just before welding.
Types of Welding-defects.
DIMENSIONAL Welding-defects can be assessed by visual inspection and by measuring with simple weld gages. They derive from improper set up or by distortion which should be controlled in a proper fixture, or by a different welding sequence. In general they should be corrected by employing proper means before welding. MISALIGNMENT is a setup problem.
Other appearance features which may cause rejection of these Welding-defects are excessive bead convexity and reinforcement, or the opposite condition, namely considerable concavity and undersized welds. Here the welder's technique should be improved.
UNDERCUT consists in a groove formed into the base metal, adjacent to the weld bead. It derives from improper manipulation of torch or electrode. Further training and improved skill of the welder should save future performance.
CRACKS are Welding-defects never permitted, because they are seen as stress raisers, and capable to grow until fracture. Different forms and positions of cracks can hint at their origin, and should be investigated before trying to correct for their appearance. Except for cases of lack of experience of the welder, who may be unable to end a weld bead without crater cracking, other instances derive mostly from limited weldability of the materials, and should be dealt with by whoever has metallurgical experience, by means of special procedures invoking pre-heat and post heat and other tricks which the welder cannot be expected to provide.
Fine cracks that cannot be seen by visual inspections, are the object of specialized inspection techniques. .
More Welding-defects...
POROSITY is a condition caused by gases remaining entrapped in the melt. This pertains generally to internal Welding-defects, which can be detected either by sectioning (which is a destructive test) or by special non destructive testing like radiography or ultrasonic testing. If this condition is determined, one should eliminate the cause, be it the material, or humidity in the electrode sheathing, or gases from excessive heat and turbulence in the melt or incorrect manipulation (improve skill).
Among other important Welding-defects one should strive to eliminate the following. INCOMPLETE FUSION, which is generally assessed by sectioning the joint (mostly a test piece) and finding the unmelted base metal that outlines the original joint shape.And INADEQUATE PENETRATION that means that the weld bead extends from its face only to a limited distance, less than what is required by the procedure.
NON METALLIC INCLUSIONS (in Shielded Metal Arc Welding) usually refer to Welding-defects in the form of slag being trapped in the melt, generally meaning insufficient skill of the welder. It could also mean oxide inclusion, in all types of welding, or tungsten metal, in Gas Tungsten Arc Welding. All these conditions can be detected either in a section or by non destructive inspection techniques.
RESISTANCE WELDING has its own set of unacceptable Welding-defects per Specification, to be determined at the stage of schedule approval by destructive testing. Shear Strength, a common Specification requirement, is determined by mechanical testing of spot welded coupons. The shape and dimensions of the weld nugget, and the appearance of Welding-defects in the form of internal cracks or inadequate fusion can only be determined in a section by destructive examinations of cut up specimens, ground, polished and etched, under a microscope.
At the production stage one should put the utmost care in manufacturing acceptable joints because it is the least expensive solution. Most of the Welding-defects are visible. The welder should be encouraged to inspect his/her own weld. Inexperienced welders should be asked to seek advice from more skilled fellow workers, and to look for help for repair in order to avoid just a cover up.
Failures in service can come up for reasons different from manual welder's skill. But this is another subject .
They are excessive conditions, outside the acceptance limits, which risks to compromise the stability or the functionality of the welded structure. They are also called rejectable discontinuities. This means that the same type of discontinuity of a lesser degree, might be considered harmless and acceptable.
Are there acceptable Welding-defects? No, by definition a defect is rejectable. There can be acceptable discontinuities. The designer, or the purchaser, or the person in charge of the welding project is entitled to define the limits of acceptance. And these limits are valid only for the application and the usage involved.
Are there undetected defects? Hopefully not! No Welding-defects should go undetected, but undetectable discontinuities yes, that are acceptable, as defined by the designer.
What should be done when Welding-defects are detected? One should reject the items and put them temporarily on hold. One should determine the cause and try to implement a corrective action to avoid future recurrence. Then an authorized professional should determine if the defects are repairable or not. If yes by which procedure. Standard procedures may be approved for routine application.
What is the difference between discontinuities and Welding-defects?
A discontinuity is an objective lack of material, an interruption in the physical consistence of a part. Examples are cracks, seams, laps, porosity or inclusions. It may or may not be considered a defect depending if it its presence endangers or not the integrity, the usefulness and the serviceability of the structure.
By knowing what is likely to produce Welding-defects one should learn how to avoid them. It is essential to distinguish discontinuities from harmful defects. Production without defects saves worktime, materials, repair costs, decrease in productivity. Excessive defect production indicates some basic condition affecting the operation which should be investigated and corrected.
Causes for rejection and how to avoid Welding-defects.
Avoidance of Welding-defects starts with correct design and preparation. This may look as an obvious statement but somehow it is a more frequent than desired situation. There is no point in trying to correct by welding for misalignment or for improper set up of the workpiece. There is no gain in time, really, only an increased probability of producing Welding-defects and of spending time and resources in trying to repair the welded item.
Also the use of recommended tools and fixtures should be implemented with no excuses admitted for temporary unavailability. The required means, in good operational condition, should be used with the correct parameters, according to the approved procedure. If the welding procedure is incapable of ensuring defect free implementation, then it should be improved upon.
The welder or the machine operator should be proficient in the process selected and all physical accessories assigned should be ready for use. Among them, aspirators of fumes, fan to circulate air, screens to protect other workers nearby, etc.
If electrodes need be dried, so they should be. Cleaning of fixtures and workpiece should be performed before setting up. A last touch up may be repeated just before welding.
Types of Welding-defects.
DIMENSIONAL Welding-defects can be assessed by visual inspection and by measuring with simple weld gages. They derive from improper set up or by distortion which should be controlled in a proper fixture, or by a different welding sequence. In general they should be corrected by employing proper means before welding. MISALIGNMENT is a setup problem.
Other appearance features which may cause rejection of these Welding-defects are excessive bead convexity and reinforcement, or the opposite condition, namely considerable concavity and undersized welds. Here the welder's technique should be improved.
UNDERCUT consists in a groove formed into the base metal, adjacent to the weld bead. It derives from improper manipulation of torch or electrode. Further training and improved skill of the welder should save future performance.
CRACKS are Welding-defects never permitted, because they are seen as stress raisers, and capable to grow until fracture. Different forms and positions of cracks can hint at their origin, and should be investigated before trying to correct for their appearance. Except for cases of lack of experience of the welder, who may be unable to end a weld bead without crater cracking, other instances derive mostly from limited weldability of the materials, and should be dealt with by whoever has metallurgical experience, by means of special procedures invoking pre-heat and post heat and other tricks which the welder cannot be expected to provide.
Fine cracks that cannot be seen by visual inspections, are the object of specialized inspection techniques. .
More Welding-defects...
POROSITY is a condition caused by gases remaining entrapped in the melt. This pertains generally to internal Welding-defects, which can be detected either by sectioning (which is a destructive test) or by special non destructive testing like radiography or ultrasonic testing. If this condition is determined, one should eliminate the cause, be it the material, or humidity in the electrode sheathing, or gases from excessive heat and turbulence in the melt or incorrect manipulation (improve skill).
Among other important Welding-defects one should strive to eliminate the following. INCOMPLETE FUSION, which is generally assessed by sectioning the joint (mostly a test piece) and finding the unmelted base metal that outlines the original joint shape.And INADEQUATE PENETRATION that means that the weld bead extends from its face only to a limited distance, less than what is required by the procedure.
NON METALLIC INCLUSIONS (in Shielded Metal Arc Welding) usually refer to Welding-defects in the form of slag being trapped in the melt, generally meaning insufficient skill of the welder. It could also mean oxide inclusion, in all types of welding, or tungsten metal, in Gas Tungsten Arc Welding. All these conditions can be detected either in a section or by non destructive inspection techniques.
RESISTANCE WELDING has its own set of unacceptable Welding-defects per Specification, to be determined at the stage of schedule approval by destructive testing. Shear Strength, a common Specification requirement, is determined by mechanical testing of spot welded coupons. The shape and dimensions of the weld nugget, and the appearance of Welding-defects in the form of internal cracks or inadequate fusion can only be determined in a section by destructive examinations of cut up specimens, ground, polished and etched, under a microscope.
At the production stage one should put the utmost care in manufacturing acceptable joints because it is the least expensive solution. Most of the Welding-defects are visible. The welder should be encouraged to inspect his/her own weld. Inexperienced welders should be asked to seek advice from more skilled fellow workers, and to look for help for repair in order to avoid just a cover up.
Failures in service can come up for reasons different from manual welder's skill. But this is another subject .
Sunday, 22 February 2009
Saturday, 21 February 2009
Prestressed concrete
Prestressed concrete
Under vertical load, bridge and building beams are subject to tensile and compressive stresses of varying intensities. The top half of the beam is subject to compression, and the bottom half is subject to tension.
Concrete is strong in resisting compression, but weak when subjected to tension. Thus, steel reinforcement is used to help concrete beams resist or compensate for tension where needed. To reinforce a concrete beam, prestressing is applied to the area of the beam which will undergo tensile stress. Since concrete is strong when compressed, prestressing takes advantage of this trait and compresses the necessary areas of the beam to balance out the tension which will occur under load. When the load is applied, the areas which were compressed by prestressing are able to stretch the necessary amount without loss of strength.
Pre-stressing can be applied in two different procedures: pretension and post-tension.
Pretension is the process whereby prestress steel strands are tensioned and then concrete is cast around them. After the concrete has hardened, the steel is released which in turn compresses the concrete.
Post-tension is a process which begins with a duct placed into the beam form. Steel strands are then threaded into the duct and post-tension anchor blocks are attached to the duct at both ends. Concrete is then cast into the form around the duct assembly. After the concrete has hardened, the strands are tensioned by jacking against the anchor blocks, inducing compression where necessary. .
Under vertical load, bridge and building beams are subject to tensile and compressive stresses of varying intensities. The top half of the beam is subject to compression, and the bottom half is subject to tension.
Concrete is strong in resisting compression, but weak when subjected to tension. Thus, steel reinforcement is used to help concrete beams resist or compensate for tension where needed. To reinforce a concrete beam, prestressing is applied to the area of the beam which will undergo tensile stress. Since concrete is strong when compressed, prestressing takes advantage of this trait and compresses the necessary areas of the beam to balance out the tension which will occur under load. When the load is applied, the areas which were compressed by prestressing are able to stretch the necessary amount without loss of strength.
Pre-stressing can be applied in two different procedures: pretension and post-tension.
Pretension is the process whereby prestress steel strands are tensioned and then concrete is cast around them. After the concrete has hardened, the steel is released which in turn compresses the concrete.
Post-tension is a process which begins with a duct placed into the beam form. Steel strands are then threaded into the duct and post-tension anchor blocks are attached to the duct at both ends. Concrete is then cast into the form around the duct assembly. After the concrete has hardened, the strands are tensioned by jacking against the anchor blocks, inducing compression where necessary. .
Friday, 20 February 2009
Thursday, 19 February 2009
Chloride Ion Content in concrete
Chloride Ion Content in concrete
Chloride ions when present in reinforced concrete can cause very severe corrosion of the steel reinforcement. The
chloride ions will eventually reach the steel and then accumulate to beyond a certain concentration level. The protective
film around the steel is destroyed and corrosion will begin when oxygen and moisture are present in the steel-concrete
interface. Chlorides can originate from two main sources as follows:
Chloride added to the concrete at the time of mixing, often referred to as Internal Chloride. This category includes
calcium chloride accelerators for rapid hardening concrete, salt contaminated aggregates and the use of sea water or other
saline contaminated water.
Chloride ingress into the concrete from the environment often referred to as External Chloride. This category includes
both de-icing salt as applied to many highway structures and marine salt, either directly from sea water in structures such
as piers, or in the form of air-borne salt spray in structures adjacent to the coast.
The effect of chloride salts depends to some extent on the method of
addition. If the chloride is added at the time of mixing, the calcium
aluminate (C3A) within the cement paste will react with the chloride to
some extent, chemically binding it to form calcium chloroaluminate. In
this form, the chloride is insoluble in the pore fluid and is not available to
take part in damaging corrosion reactions.
The ability of the cement to chemically react with the chloride is however
limited and depends on the type of cement. Sulphate resisting cement,
for example, has a low C3A content and is therefore less able to react with
the chlorides.
Experience suggests that if the chloride exceeds about 0.4% by mass of cement, the risk of corrosion increases. This
does not automatically mean that concretes with chloride levels higher than this are likely to suffer severe reinforcement
corrosion: this depends on the permeability of the concrete and on the depth of carbonation in relation to the cover
provided to the steel reinforcement.
When the concrete carbonates, by reaction with atmospheric
carbon dioxide, the bound chlorides are released. In effect this
provides a higher concentration of soluble chloride immediately in
front of the carbonation zone. Normal diffusion processes then
cause the chloride to migrate into the concrete. This process, and
normal transport of chlorides caused by water soaking into the
concrete surface, is responsible for the effect sometimes observed
where the chloride level is low at the surface, but increases to a
peak a short distance into the concrete (usually just in front of the
carbonation zone). The increase in unbound chloride means that
more is available to take part in corrosion reactions, so the
combined effects of carbonation and chloride are worse than either
effect alone.
The depth/concentration profile for External chloride, which has penetrated hardened concrete, will show levels decreasing
further from the surface. Chlorides present in the fresh concrete will tend to be evenly distributed throughout the concrete.
Passivation of the steel reinforcement in concrete normally occurs due to a two component system comprising a
portlandite layer and a thin pH stabilised iron oxide/hydroxide film on the metal surface. When chloride ions are present,
the passivity of the system is lost by dissolution of the portlandite layer, followed by debonding of the passive film. Physical
processes operating inside the passive film may also contribute to its disruption.
When chlorides have ingressed from an external source, particularly in conditions of saturation and low oxygen availability,
insidious pitting corrosion of the reinforcement can occur, causing massive localised loss of cross section. This can occur
in the early stages without disruption of the concrete underneath.
The critical chloride content required to initiate corrosion depends on
whether the chloride was present at the time of mixing, or has
ingressed after hardening, as discussed above. Clearly this also
depends on the temperature and humidity of the concrete and also
whether the concrete has carbonated. Good quality concrete can
often show a remarkable tolerance for chloride without significant
damage, however, at chloride contents up to about 1% by mass of
cement (usually for chloride added at the time of mixing) reinforced
concrete is much less tolerant of ingressed chloride.
There is little published data on the accuracy and precision of the
methods for chloride analysis. For the presentation of results, TRL
Contractor Report 32 warns of the potential errors associated with
assuming a cement content as the small size of the samples taken for
analysis may not be representative of the actual concrete
composition.
BS 8110 limits the permitted chloride content from all sources to 0.35% by weight of cement for reinforced concrete
structures. Concrete Society Technical Report No. 32 suggests that the risk of chloride-induced corrosion is significant for
levels greater than 0.6%.
BA 35/90 states that where chloride ion content at the level of reinforcement exceeds 0.3% (total chloride ion content) by
weight of cement, there is a risk of corrosion occurring.
To determine chloride ion content concrete dust samples are collected by drilling incrementally using a 25mm diameter
percussion drill and collecting the dust (after discarding the first 5mm), at 5-25mm, 25-50mm 50-75mm and 75-100mm.
These samples are then tested in our UKAS accredited laboratory in accordance with BS 1881: Part 124: 1988.
References:
BS 1881: Part 124: 1988 – Testing Concrete, Methods for analysis of hardened Concrete
BS 8110: Part 1: 1997 - Structural use of concrete. Code of practice for design and construction
BA 35/90: 1990 – The Inspection and Repair of Concrete Highways Structures
TRL Contractors Report 32: 1986 - Methods to determine chloride concentrations in in-situ concrete
My update C.V 15-02-2009
My update C.V
Faris Abdulrazzag Rasheed
2/15/2009
3/4/5/17 Alwaha-Kober-Khartoum North-Sudan00249129400884(Sudan),+9647902305615(Iraq)efalr1959@yahoo.com
http://www.farisalmahdawi.blogspot.com/
Objectives
To direct bridge construction projects for contractors or consultants companies
Education
· B.Sc. Civil Engineering -University of Baghdad – Baghdad- Iraq.1980
Attended training courses
I've attended several national and international training courses.
Technical Training Courses In:
1. Piling Equipments and Techniques/ SoilMec. Piling co. Rome/ Italy May/2004
2. Pile foundation and sheet piling/NCCL/Iraq.
3. Techniques of pre-stressed concrete structures/University of Technology Iraq.
4. Design of common bridges/Cowi Consult/SORB/Iraq.
5. A training course in survey work and road design/SORB/Iraq.
6. Job mix design of asphaltic concrete/ NCCL/Iraq.
7. Non destructive concrete test/ University of Technology Iraq
8. Projects management /NCCL/Iraq
9. Quantity and price estimation for large projects and bridges/SORB/Iraq
10. .Pile construction /Ministry of housing and construction/Iraq.
11. Types of bridges /SORB/Iraq.
1980 - 1985
· Muthana Airport-Baghdad.
· Baghdad international airport-Baghdad.
· Al-Baghdadi Airport-Haditha.
· Air Force Officer’s Club-Baghdad.
Assistant of resident engineer Hammurabi Contracting Company
1985-1987
· Khaldiya Concrete Bridge Project- Alanbar.
· 14th Ramadan Concrete Bridge -Baghdad.
Assistant for project manager Ministry of Housing-SORB
1987-1989
· Radhwaniya Concrete Bridge –Baghdad.
· Concrete bridge for rail way - Abu Graib-Baghdad.
· Three concrete bridges (Arch) in Presidential sites – Baghdad.
· Two concrete bridges on the major drain (Al- Massab Al-AAM)-Baghdad.
· Pedestrian bridge – Ramadi.
· Three steel bridges over Tharthar Canal-Baghdad.
Project manager Hamorabi Contracting Company
1989-1992
· Two concrete bridges for rail way - Beiji.
· Over pass concrete bridge over the main road Baghdad – Mosul in the zone- Beiji.
· Over pass concrete bridge over Beiji / Mosul road- Makhol ( Sinia- Makhol Intersection).
· Large concrete culverts crossing embankment of rail way –Beiji.
Project manager Hammurabi Contracting Company
1993-1996
· Concrete bridge on Tharthar Canal at KM/11
· Concrete Arch bridge in Tikrit in the Presidential site.
· Concrete bridge on Tharthar Canal at KM/19.
· Arch bridge in (Salam Palace) – Baghdad.
Central Batching Plant Manger and Head of Piles Section Hammurabi Contracting Company 1997-2000
Project manager Hammurabi Contracting Company
2001-2003
· Al-A’mara bridge project-Baghdad.
· Zawraa Park Concrete Arch Bridge – Baghdad.
· Project Manager of concrete bridge on site100 (Presidential Site)- Baghdad .
Head of Bridge Department Hamorabi Contracting Company
2004-2007
· Work includes technical and administrative directing and supervising upon bridges projects under construction, quantity and price estimation for projects to be attended by the company, follow up with the time frame schedule of projects, technical and administrative support for all precast concrete elements produced by company including concrete batch plants.
· Projects executed during period are:
· Chabab Bridge - Kut.
· Dejaili & Janabi bridge – Kut.
· Diyala Bridge - Baghdad.
· Shanafiya Bridge –Diwaniya.
· Kefil bridge - Najaf
· Abbasiyat Bridge –Najaf.
· Warrar Bridge - Ramadi.
· Zuhoor Intersection - Baghdad.
· Dakook , Sulaiman Beck, Tooza and Quri Chai bridges – Kirkuk.
· Girders & culverts Plant - Baghdad.
- Resident Engineer-Span for Consultancy Engineering
2008 -2009
· Al-Halfaya Bridge Project- Omdurman/ SUDAN.
skills
Computer skills: M.S Office applications (Word, Excel, Access, PowerPoint…etc.) and internet navigating.
£ Languages: Arabic (mother tongue), English (fluent speak and write).
£ Languages: Arabic (mother tongue), English (fluent speak and write).
Friday, 13 February 2009
Tuesday, 10 February 2009
Friday, 6 February 2009
Thursday, 5 February 2009
Wednesday, 4 February 2009
Concrete Test Hammer
Concrete Test Hammer
Concrete test hammer uses indirect means of obtaining relative value for compressive strength of finished concrete. Spring-driven hammer is used for non-destructive quality testing of concrete and other building materials in any structure or prefabricated section. Determines when forms may be removed or load applied, damage done to a structure by freezing or fire. Impact energy is 1.6 ft-lbs. (2.207 Nm). Unit has 1450 to 10,150 psi (10 to 70 N/mm2) capacity range. Lightweight portable test instrument works on the rebound principle. To operate, place impact plunger against test surface and apply pressure until plunger disappears; hammer will release. Scale pointer reading gives rebound value in percent of the forward movement of the hammer mass. Includes rubbing stone, plastic case, instruction booklet and calibration curves. Meets ASTM C805
A Schmidt hammer, also known as a Swiss hammer, is a device to measure the elastic properties or strength of concrete or rock.
Original Schmidt Concrete Test Hammer
The hammer measures the rebound of a spring loaded mass impacting against the surface of the sample. When conducting the test the hammer should be held at right angles to the surface which in turn should be flat and smooth. The rebound reading will be affected by the orientation of the hammer, when used in a vertical position (on the underside of a suspended slab for example) gravity will increase the rebound distance of the mass and vice versa for a test conducted on a floor slab. The Schmidt hammer is an arbitrary scale ranging from 10 to 100. Schmidt hammers are available from their original manufacturers in several different energy ranges. These include: (i) Type L-0.735 Nm impact energy, (ii) Type N-2.207 Nm impact energy; and (iii) Type M-29.43 Nm impact energy.
The test is also sensitive to other factors:
Local variation in the sample. To minimise this it is recommended to take a selection of readings and take an average value.
Water content of the sample, a saturated material will give different results from a dry one.
Prior to testing, the Schmidt hammer should be calibrated using a calibration test anvil supplied by the manufacturer for that purpose. 12 readings should be taken, dropping the highest and the lowest, and then take the average of the ten remaining. Using this method of testing is classed as indirect as it does not give a direct measurement of the strength of the material. It simply gives an indication based on surface properties, it is only suitable for making comparisons between samples.
Original Schmidt Concrete Test Hammer
The hammer measures the rebound of a spring loaded mass impacting against the surface of the sample. When conducting the test the hammer should be held at right angles to the surface which in turn should be flat and smooth. The rebound reading will be affected by the orientation of the hammer, when used in a vertical position (on the underside of a suspended slab for example) gravity will increase the rebound distance of the mass and vice versa for a test conducted on a floor slab. The Schmidt hammer is an arbitrary scale ranging from 10 to 100. Schmidt hammers are available from their original manufacturers in several different energy ranges. These include: (i) Type L-0.735 Nm impact energy, (ii) Type N-2.207 Nm impact energy; and (iii) Type M-29.43 Nm impact energy.
The test is also sensitive to other factors:
Local variation in the sample. To minimise this it is recommended to take a selection of readings and take an average value.
Water content of the sample, a saturated material will give different results from a dry one.
Prior to testing, the Schmidt hammer should be calibrated using a calibration test anvil supplied by the manufacturer for that purpose. 12 readings should be taken, dropping the highest and the lowest, and then take the average of the ten remaining. Using this method of testing is classed as indirect as it does not give a direct measurement of the strength of the material. It simply gives an indication based on surface properties, it is only suitable for making comparisons between samples.
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