Asphalt vs Bitumen

RENUNGAN

INTEGRITI

TERIMA AMANAH

Sesungguhnya kami (Allah) telah menawarkan amanat kepada langit, bumi dan gunung-ganang, maka semuanya enggan untuk memikul amanat itu dan mereka khuatir akan mengkhianatinya. Maka dipikullah (diterimalah) amanat itu oleh manusia. (Ingatlah) sesungguhnya tabiat manusia itu amat zalim dan amat bodoh (suka melakukan perkara yang tidak wajar). (Al-Ahzab: 72)

JANGAN KHIANAT

Wahai orang-orang yang beriman! Janganlah kamu mengkhianati (amanah) Allah dan RasulNya, dan (janganlah) kamu mengkhianati amanah-amanah kamu, sedang kamu mengetahui (salahnya). (Al-Anfaal: 27)

PERLU PROFESIONALISMA

Dari Abu Hurairah RA Berkata: Rasullullah SAW bersabda, "Jika amanat disia-siakan, maka tunggulah kehancuran. Sahabat bertanya "Bagaimana menyia-nyiakannya ya Rasullullah?. Jawab Rasulullah SAW:" Jika urusan diserahkan kepada orang yang bukan ahlinya (tidak mahir/ tidak kompeten/tidak profesional/ tidak pakar) maka tunggulah kehancurannya.

PILE TESTING

Malaysia Practice (JKR/SPJ/1988 )

The pile can then be tested by one of two static load tests:

1. Maintained load test

2. Constant Rate of Penetration (CRP) test.

Maintained Load Test

The Maintained Load Test shall be carried out as follows:-

1. the full test load on pile shall be twice the design load noted on the Drawings and it shall be applied in twelve equal increments. At least two hours shall elapse between the addition of each load increment, i.e. until the rate of settlement is reduced to less than 0.25mm/hour and slowing down;



2. the full test load shall be maintained on the pile for at least 48 hours and settlements shall be recorded at intervals of not more than 12 hours. The test pile shall then be unloaded in four equal increments at one hour intervals until the full load is removed. Settlement readings shall be made immediately after and before every load increment is applied or removed.

Constant Rate of Penetration (CRP) Test

For each pile load test, three cycles of pile loading test at a constant rate of penetration shall be carried out to a full test load equal to twice the design load.

The rate of loading shall be such that a constant rate of penetration is maintained throughout the rest insofar as is practicable. The rate of movement of each pile to be tested shall be agreed upon with the S.O prior to the start of the test. At least twelve readings of settlements and their corresponding loads shall be made in the loading process.

After attaining a test load equal to twice the design load, the load shall gradually be released and at least four readings of settlement and their corresponding loads shall be made during the unloading process. The settlement obtained when the load has been completely released shall also be recorded. An interval of at least 15 minutes shall elapse before the next CRP test is commenced.

Interpretation of Test Results

The S.O's interpretation and conclusions on the test results shall be final. Unless otherwise specified, the pile so tested shall be deemed to have failed if:-

1. the residual settlement after removal of the test load exceeds 6.5mm; or

2. the total settlement under the Working Load exceeds 12.50mm; or

3. the total settlement under twice the Working Load exceeds 38.0mm. or 10% of pile diameter/width whichever is the lower value.

Hong Kong Practice

Maintained Load Test

At present, this is the most popular pile test used in Hong Kong. The equipment required for loading the pile is assembled across the top of the pile. The hydraulic jack and the load cell are placed on top of the pile. The ram of the jack is extended until the load cell touches the underside of the main RSJ of the loading frame. Equipment to measure pile settlement is then set up, and the zero reading s are noted.

Before carrying out the load test, the engineer will state the working load and the test load, and he will describe the different stages of loading in the test. Most specification give the test load as twice the working load. The test load is applied in increments of about 25 percent of the working load, until the working load is reached. Smaller increments are added thereafter until the specified limit is reached.

Loading tests are usually carried out in a cycle. Each stage of the loading test or increment of load is applied as smoothly and quickly as possible. Readings of load, time and settlement are taken when loading commences, and at intervals as the load increases. Each increment of load is allowed to remain until settlement has ceased. Similarly, unloading of each incremental load must not commence until recovery has ceased. In general, settlement or recovery is assumed to have ceased when the rate of movement is 0.25 mm per hour.

When the maximum test load is reached, the applied load is unload progressively to zero load. Measurements are recorded again during the unloading process.

Some specifications may require the load to be unloaded at intermediate stages, either progressively or in one operation. In such cases, the load is then re-applied either in increments or in one operation.

Most Hong Kong specifications require that after unloading, the maximum test load be applied again in one operation, and be maintained for a minimum period of 72 hours. It is the step unloaded to zero load.

Graphs of load against time, load against settlement, and settlement against time are then plotted. These graph s are used to determine if the pile has satisfied the requirements of the specification.

The pile is deemed to have failed the test if:

1. the total pile settlement > Z + D/120 + 4 mm

2. and residual pile settlement > D/120 + 4 mm
   
   
   where D = diameter of circular or least lateral nominal dimension of other piles in mm.
   Z = L (2P+Pt)/3AE mm
   
   P = test load ( kN )
   L = length of pile ( m )
   A = cross-section of pile ( m² )
   E = Young's modulus of elasticity of pile ( kN/m² ).
   Pt = resistance at the tip of the pile
   = 2APb( kN ) where
   
   Pb =safe bearing capacity of sub-soil strata at the tip of the pile ( kN/m² ). This can be calculated from the appropriate soil parameters obtained by site investigation.

Constant Rate of Penetration (CRP) Test

The equipment used in the constant rate of penetration (CRP) test is the same as that used in the maintained load test. However, the method of loading is different.

In the CRP test, the pile is made to penetrate the soil at a constant speed. This is achieved by increasing the applied force. The force applied to the head of the pile to maintain this constant rate of penetration varies and is measured continuously. As a result of the pile movement, the soil is stressed progressively until it fails in shear. When this occurs, the ultimate bearing capacity of the pile is reached.

Before the test is begun, the hydraulic jack and the load cell are inserted between the pile head and the reaction system. The jack is then operated to cause the pile to penetrate the soil at a uniform speed. Readings of time, penetrate rate and jacking force are made at convenient intervals. A penetration rate of about 0.75 mm/min. is a suitable choice for friction piles in clay, while a penetration rate of about 1.5 mm/min. is a suitable choice for end bearing piles in sand or gravel. However, the actual rate may vary depending on the pumping equipment available.

The test usually proceeds very rapidly and requires the services of several observers to take simultaneous readings.

As the test proceeds, a graph of force against penetration is made to determine when the ultimate bearing capacity is reached. Typical graphs for a friction pile and an end bearing pile are shown in the Fig. pt.9. and pt. 10. For a predominantly friction pile, the value of the force at the point A in Fig. pt. 9 represents the ultimate bearing capacity.

For a predominantly end bearing pile, the ultimate bearing capacity in most cases is taken as the force at which the penetration is equal to 10 percent of the base diameter of the pile. However, two factors that should be borne in mind are:

1. for a very long pile, the elastic shortening of the pile during the test may reach 10 percent of the base diameter: and



2. for a large pile, there may be difficulty in loading the pile to a settlement as great as 10 percent of its base diameter.

When either of the above two cases is encountered, the ultimate bearing capacity is usually estimated roughly from the load settlement curve.

Engineering Term

1. Buttress

Noun
i. a construction, usually of brick or stone, built to support a wall
ii. any support or prop

Verb
i. to support (a wall) with a buttress
ii. to support or sustain

2. Fatigue

Noun
the weakening of a material caused by repeated stress or movement

3. Borrow Pit

Noun
a pit created to provide earth that can be used as fill at another site

RC Deep Beam

What is RC Deep Beam ?

Deep beams are structural elements loaded as beams in which a significant amount of the load is transferred to the supports by a compression thrust joining the load and the reaction. As a result, the strain distribution is no longer considered linear, and the shear deformations become significant when compared to pure flexure.

Floor slabs under horizontal load, short span beams carrying heavy loads, and transfer girders are examples of deep beams.

RC deep beams have many useful applications in building structures such as transfer girders, wall footings, foundation pile caps, floor diaphragms, and shear walls.

EXAMPLE

RC deep beams, which fail with shear compression, are the structural members having a shear span (orange line(a)) to effective depth (black line(d)) ratio, a/d, not exceeding 1.

Balanced Cantilever

(Info From BBR Holdings)

With the cantilevering method, the superstructure of bridges is usually built from one or more piers by means of formwork carriers. Normally the structure advances from a short stub on top of a pier symmetrically in segments of about 3 m to 5 m length to the mid span or to an abutment, respectively (load balancing method).

The prestressing tendons are arranged according to the moment diagram of a cantilever, with a high concentration above the pier. Towards the mid span or the abutment the number of tendons gradually decreases.

The use of the cantilevering construction method, for medium and long span concrete bridges, is recommended especially where a scaffolding is difficult or impossible to erect as e.g., over deep valleys, wide rivers, traffic yards or in case of expensive foundation conditions for scaffolds.

Incremental Launching

(Info From BBR Holdings )

The incremental launching method is particularly suited for the construction of continuous post-tensioned multi-span bridges. It consists of casting 15 m to 30 m long sections of the bridge superstructure in a stationary formwork behind an abutment to push a completed section forward with jacks along the bridge axis.

The sections are cast contiguously, one after another and are then stressed together. The superstructure, growing section by section is launched over temporary sliding bearings on the piers until the bridge is completed. In order to keep the bending moment low in the superstructure during the extrusion phases, a launching nose made of steel is attached to the front of the bridge deck. The launching nose is dismantled after the superstructure has reached the opposite abutment.

However, the spans should not exceed 60m approx. and the bridge sections must be constant. Furthermore the superstructure of the bridge has to be continuous over the whole length and straight or have a constant curvature in plan and elevation.

Space Frame Design

Rules of Thumb for Space Frame Design

It is important for the architect to work side by side with the engineer when considering a space frame system. While the engineer normally sizes up the structural members after the architect has designed the structure, his/ her role must be more interactive to ensure that each design decision takes full advantage of a space frame system while managing costs. Simply changing the modular sizes of the space frame components could have a huge impact on material costs.

Typically, space frames are not as economical for spanning systems under 7-10 metre in length.

For determining depth of space frame;

a. Use ratio of 1:12 depth to span for a 1-way space frame.
b. Use ratio of 1:15 depth to span for a 2-way space frame.
c. Use ratio of 1:18 depth to span for a 3-way space frame.

Potholes

Small, bowl-shaped depressions in the pavement surface that penetrate all the way through the HMA layer down to the base course. They generally have sharp edges and vertical sides near the top of the hole. Potholes are most likely to occur on roads with thin HMA surfaces (25 to 50 mm (1 to 2 inches)) and seldom occur on roads with 100 mm (4 inch) or deeper HMA surfaces (Roberts et al., 1996).

Pothole on a residential road after heavy rains.




Pothole as a result of fatigue cracking.

Fatigue cracking showing the beginning of a pothole.

Road Maintenance & Rehabilitation (Info)

The combined effects of traffic loading and the environment will cause every pavement, no matter how well-designed/constructed to deteriorate over time. Maintenance and rehabilitation are what we use to slow down or reset this deterioration process. Maintenance actions, such as crack sealing, joint sealing, fog seals and patching help slow the rate of deterioration by identifying and addressing specific pavement deficiencies that contribute to overall deterioration. Rehabilitation is the act of repairing portions of an existing pavement to reset the deterioration process. For instance, removing and replacing the wearing course in a pavement provides new wearing course material on which the deterioration process begins anew. Reconstructing an entire pavement, however, is not considered rehabilitation but rather new construction because the methods used are generally those developed for new pavement construction.

Crocodile (Alligator) Cracks :- Fatigue Cracks

Description:
Series of interconnected cracks caused by fatigue failure of the HMA surface (or stabilised base) under repeated traffic loading. In thin pavements, cracking initiates at the bottom of the HMA layer where the tensile stress is the highest then propagates to the surface as one or more longitudinal cracks. This is commonly referred to as "bottom-up" or "classical" fatigue cracking. In thick pavements, the cracks most likely initiate from the top in areas of high localised tensile stresses resulting from tire-pavement interaction and asphalt binder aging (top-down cracking). After repeated loading, the longitudinal cracks connect forming many-sided sharp-angled pieces that develop into a pattern resembling the back of an alligator or crocodile.

Problem:

Indicator of structural failure, cracks allow moisture infiltration, roughness, may further deteriorate to a pothole.

Possible Causes:

Inadequate structural support, which can be caused by a myriad of things. A few of the more common ones are listed here:

Decrease in pavement load supporting characteristics

• Loss of base, subbase or subgrade support (e.g., poor drainage or spring thaw resulting in a less stiff base).

• Stripping on the bottom of the HMA layer (the stripped portion contributes little to pavement strength so the effective HMA thickness decreases)

Increase in loading (e.g., more or heavier loads than anticipated in design)

Inadequate structural design

Poor construction (e.g., inadequate compaction)

Repair:

A fatigue cracked pavement should be investigated to determine the root cause of failure. Any investigation should involve digging a pit or coring the pavement to determine the pavement's structural makeup as well as determining whether or not subsurface moisture is a contributing factor. Once the characteristic alligator pattern is apparent, repair by crack sealing is generally ineffective. Fatigue crack repair generally falls into one of two categories:

• Small, localised fatigue cracking indicative of a loss of subgrade support. Remove the cracked pavement area then dig out and replace the area of poor subgrade and improve the drainage of that area if necessary. Patch over the repaired subgrade.

• Large fatigue cracked areas indicative of general structural failure. Place an HMA overlay over the entire pavement surface. This overlay must be strong enough structurally to carry the anticipated loading because the underlying fatigue cracked pavement most likely contributes little or no strength (Roberts et. al., 1996).

CONCRETE BLOCK PAVING (CBP)

CBP is more resistant to wear from applied loads than premix asphalt (ACWC). For this reason CBP is usually the preferred material where the following conditions apply:

• Heavy (industrial) loadings are applied to the surface
• Stop/Start traffic (traffic light junction)
• Turning and slewing wheels
• Petro-chemicals or other contaminants in contacts with the pavement surface
• Cushion or solid tyred wheels.

Cost comparison between CBP and Premix Asphalt will be given for next post based on JKR experiance especially for the traffic light junctions.

PMA - JKR Experiance

Poor quality of asphalt binder is one of the causes for early deterioration of asphalt concrete surface, especially with high traffic volume roads. During the past 15 years, rutting in conventional asphalt concrete highway due to the substantial increase in traffic volume has become major problem facing motorists. PWD of Malaysia have revised to tackle the problem by using 60-70 penetration grade asphalt instead of the usual 80-100. This, however, resulted in fatigue cracking and fretting and hence became a serious problem. Polymer modified asphalt has then been used to improve the asphalt cement properties. Asphalt concrete has more resistance to deformation, more stiffness and elasticity after the application of polymer modified asphalt. The mixture demonstrates high resistance to rutting, fatigue cracking and fretting. From the first modified asphalt concrete road pavement in Kelantan (Jalan PCB), it was found that the durability, stability, strength index and bond between aggregates and binder of the polymer modified asphalt were improved.

INFO Kerja Penurapan Jalan

"JALAN YANG BARU DITURAP DAN SELESAI DIGELEK TIDAK BOLEH DIBUKA KEPADA TRAFIK SEHINGGA BAHAN TURAPAN TELAH SEJUK. PADA KEBIASAANNYA TIDAK KURANG DARIPADA EMPAT JAM(4 JAM) SELEPAS DIGELEK"

Polymer Modified Asphalt (PMA)

Info From "http://www.semmaterials.com/"

What, How, Why?

The term "polymer" simply refers to a very large molecule made by chemically reacting many (poly) smaller molecules (monomers) to one another in long chains or clusters. The physical properties of a specific polymer are determined by the sequence and chemical structure of the monomers from which it is made. When polymers are added to asphalt, the properties of the modified AC depend on two things:

• the polymer system used
• the compatibility of the polymer with the asphalt.

Why modify?

Improvement in resistance to rutting, thermal cracking, fatigue damage, stripping, and temperature susceptibility have led polymer modified binders to be substituted for asphalt in virtually all paving and maintenance applications, including hot mix, warm mix - cold lay, cold mix, chip seals, hot and cold crackfilling, patching, recycling, and slurry seal. They are used wherever extra performance and durability are desired. In many cases they are selected to reduce life cycle costs. Polymer modified binders have allowed the use of techniques previously not practicable, such as micro-surfacing and using emulsion chip seals on high traffic roads.

Rocks

abstract from " A Guide to good quality control practices on asphalt production and construction"

Rocks are classified relative to their geological origins and these are termed Igneous, Sedimentary and metamorphic

1. Igneous Rocks

formed from hot liquid or magma, cooling either above or beneath the earth's surface.
examples are Grannite & basalt

2. Sedimentary Rocks

The action of wind or water on a rocks surface results in the formation of smaller particles. These particles are deposited on river or sea beds or depressions in the earth's surface. This sediment accumulates and is buried. Compaction and cementation over the years removes the air and water to form sedimentary rocks.
Typical example is Limestone

3. Metamorphic rocks

Heat, pressure and chemical substances deep beneath the earth's surface act on existing igneous and sedimentary rocks to form a new type called metamorphic rocks, example marble

Allahyarham Mohd Azlan Hamid

Rakan-Rakan semua, saya baru balik ziarah Sahabat kita, keadaan amat tenang sekali, suasana persekitaran kampung amat sesak dengan jiran-jiran dan rakan-rakan menziarahi arwah. Saya sempat menatapi wajah arwah dan sayu rasanya sehingga tidak sedar mengalir keluar air mata. Wajah arwah berseri dan ahli keluarganya tenang. Cuma terdengar tangisan anak kecil yang mungkin belum memahami keadaan ini.

Al-Fatihah kepada Allahyarham Mohd Azlan. Semoga rohnya dicucuri rahmat.

AL-FATIHAH

Rakan-Rakan X-UiTM 1991 - 1993,
Sahabat kita Mohd Azlan Hamid (Pak Lan) telah meinggal dunia pada pukul 9.00 malam tadi. Pemergiannya amat dirasai. Rasanya baru semalam terdengar riuh-rendah dengan kata-kata yang melucukan tetapi boleh dijadikan renungan dan pedoman. Sama-sama kita mendoakan Semoga Rohnya dicucuri Rahmat. Al-Fatihah.

Ini Baru Dinamakan Innovatif Teknologi

Untuk renungan bersama Rakan-Rakan

Ravelling

What is Ravelling?

Ravelling is the loss of surface aggregate from a bituminous surfacing mixture. Ravelling affects the integrity of the mix. If it is not halted it may cause deterioration to the extent where the surfacing mix no longer performs competently, resulting in a lack of waterproofing and causing an uncomfortable ride.

What Causes Ravelling?

Causes of ravelling can be dirty aggregate, segregation on the surface and poor compaction. In the case of dirty aggregate the bitumen sticks to the dust not to the stone and thus traffic can flick out the poorly held stone. In areas where the grading is deficient in fines, the coarse aggregate is effectively depleted of binder. As the binder ages the bond weakens, or stripping occurs. This rips the coarse aggregate out.

Poor compaction can also be a cause of raveling. Cohesion may be too low and the material will fret away under traffic.

Pavement Defect - Bleeding

Bleeding refers to the accumulation of asphalt binder (cement) on the pavement surface - normally in the wheelpath areas. Bleeding can be caused by excess asphalt cement and/or insufficient voids in the asphalt mix, with the excess asphalt being flushed to the pavement surface by wheel loads during hot weather. Pavement areas affected by bleeding reduce the friction available for aircraft braking and can become very slippery - especially when wet.

COLD IN-PLACE RECYCLING

This innovative road reconstruction process is a cost-effective alternative to more traditional methods of rebuilding asphalt roadways. It is used when existing pavement has aged, cracked or deteriorated beyond the point that normal road maintenance operations are practical or cost effective.

With single-unit Cold In-Place Recycling Train, a highly-efficient milling machine excavates the existing asphalt pavement to a depth of 75mm - 300mm to eliminate cracks, ruts and oxidized asphalt. The down-cutting action of this specially-designed milling machine sizes the asphalt and immediately blends it with a specially-formulated asphalt emulsion. This emulsion mixes with the milled pavement and acts as a binder to form the new recycled asphalt pavement. Finally, this new mixture is placed on the roadway by a bituminous paver and compacted as a new and more durable 75mm - 300mm asphalt base course. This new base course is placed at the grade and cross-slope as required by project specifications.

Major road detours and obstructions normally associated with road reconstruction are eliminated with the Cold In-Place Recycling Process. This entire reconstruction takes place in a single lane at a time, allowing traffic to flow unimpeded around the recycling operation. Access into and out of driveways can be provided during construction so deliveries and businesses are minimally interrupted. Another positive aspect of this process is that all of the construction is conducted within a span of approximately 30 to 40m. This relatively small work area can greatly reduce the delay time motorists generally experience in conventional construction work zones.
Following a brief curing period of approximately one week, a surface course of new hot mix asphalt 40mm to 60mm in depth is applied on top of the recycled base to complete the road reconstruction process. The thickness of the new surface mix placed over the recycled base will depend upon the use and traffic loading of the area being reconstructed.

Cold In-Place Recycling has been used since the early 1980's to reconstruct nearly every type of asphalt-based roadway. These projects include "farm-to-market" roads that were constructed without a proper asphalt base, busy residential roads, urban commuter thoroughfares, and major feeder systems for industrial parks. Some roads completed with this process now handle in excess of 15,000 to 20,000 vehicles per day.

Cold In-Place Recycling can be used to rehabilitate all types of asphalt pavement including airport taxiways/runways and parking lots for heavy industrial, commercial and institutional uses.

THE BENEFITS OF COLD IN-PLACE RECYCLING INCLUDE;

ENVIRONMENTALLY SUPERIOR CONSTRUCTION

• No Asphalt is Wasted - 100% is efficiently reused
• Natural resources are preserved
• Landfill space is not taken up by a recyclable resource

MINIMAL USER IMPACT

• Faster reconstruction
• Road that could have taken weeks to rebuild can be recycled in just a few days or less.
• Less commuter delay
• In most cases, the recycled road remains open to traffic throughout the reconstruction. Residents are minimally affected
• Businesses remain open and deliveries can be maintained
• Emergency services and bus transportation continue with minimal delay

LOWER COST

• A typical Cold In-Place Recycling project is one-half to one-third the cost of traditional total reconstruction methods
• In US, Cold In-Place Recycling saves taxpayers over $300 million each year.

STRONGER ROADS

• Recycling builds thicker asphalt bases, providing roads with a stronger foundation and renewing their lifespan to that of their original construction

Cold In-Place Recycling is one of the fastest growing road reconstruction techniques available. It is fast, cost-efficient, and can produce a strong base course using existing road material. When your asphalt roads have deteriorated to the point that they need to be reconstructed, consider utilizing Cold In-Place Recycling to build a stronger road base, save tax dollars, minimize traffic delays, and help conserve our valuable natural resources.

FAQ ON CiPR

How do I know if my road is a good candidate for Cold In-Place Recycling(CiPR)?

• Generally speaking, any asphalt roadways with good structural strength coupled with at least 100mm - 150mm of existing asphalt material are good candidates. However, each road must be evaluated on an individual basis to determine whether or not it is a good candidate for the process. Use of this process for heavy-duty roads or high-speed, high-traffic roads may not be appropriate.
  

What types of additives are used in the process?

• The most common additive is asphalt emulsion; however, lime slurry, portland cement, fly ash or a combination of these additives are also used.

What types of problems can recycling correct?

• Recycling can correct problems such as rutting, raveling, polishing of aggregates, bleeding, shoving as well as poor profiling. Basically any type of surface defect.
  

How long will a recycled road last?

• Most properly designed recycled pavements last as long as a comparable virgin hot-mix pavement.
  

How thick/deep can you cold recycle?

• The equipment is limited to 250mm - 300 mm. However, the primary limitation is curing and compaction. The deeper you cold recycle, the more compaction equipment is necessary. Also, aeration may be necessary for curing on deep recycle projects.

What does the end product look like?

• The end product usually looks like a base paving material. In some cases a fog seal is placed on the surface which protects it from the elements as well as giving the material a uniform black surface appearance.
  

How much additive is used?

• The amount of additive is determined by the mix designs from material sampled from the roadway. Typical asphalt emulsion contents range from 13% by weight of the RAP. When cement or lime are used typical application rates are from 13%. When fly ash is the additive the application rate varies from 5 - 12%.
  

How much can I save using CIPR?

• Typically cost savings vary from 25% to 33% over other equivalent alternatives.

What are the environmental benefits of CIPR?

• No heating is used during the process thereby reducing the use of fossil fuels and also reducing air pollution. Also, the existing aggregate and asphalt cement is reused thereby decreasing and/or eliminating the need for virgin aggregate and asphalt cement in the process. Total energy savings of from 40% to 50% can be achieved using this processes versus conventional approaches.
  

What are the traffic restrictions during and after construction?

• Traffic is kept off the finished product until compaction is complete. There is no need to wait for the material to cool or setup because it is not heated. This helps facilitate the speedy return to traffic and reduces user delays. The recycled lane may be opened to traffic one hour after completion of the day's work.
  

How many years has the process been used?

• Various forms of cold recycling have been used for many years. The advanced cold recycling systems with sophisticated processing and additive controls have been around since the early 1980's.
  

Can the process be used at night?

• CIPR has been used at night. Depending on the type of additive in use and the weather conditions curing may be slower. However, it has been successfully performed.
  

What are the weather and temperature limitations?

• The weather and temperature limitations will vary depending on the additives in use. Generally, asphalt emulsions are used when the temperature is 18ºC and rising and the conditions are not rainy or wet. Each project should be evaluated individually by a local expert to determine its viability.
  

What surfacing do you apply?

• It is recommended that all Cold In-Place Recycling projects receive a seal or overlay. A pavement design is required to determine how much if any overlay is necessary.
  

How soon may a surface course be applied?

• It is generally recommended that the moisture content of the recycled material not be greater than 1.5 % above the "free moisture" content of the original existing pavement before overlay or sealing. Light fog seals are commonly placed the same day as construction, however.
  

Can you reprofile the road?

• A certain amount of reprofiling may be performed with the Cold In-Place Recycling process. Severe geometrical problems cannot be rectified without premilling the surface prior to Cold In-Place Recycling.
  

Are specifications available?

• Yes, JKR/SPJ/2008-S4

Preventive Maintenance

Preventive maintenance is a schedule of planned maintenance actions aimed at the prevention of breakdowns and failures. The primary goal of preventive maintenance is to prevent the failure of equipment before it actually occurs. It is designed to preserve and enhance equipment reliability by replacing worn components before they actually fail. Preventive maintenance activities include equipment checks, partial or complete overhauls at specified periods, oil changes, lubrication and so on. In addition, workers can record equipment deterioration so they know to replace or repair worn parts before they cause system failure. Recent technological advances in tools for inspection and diagnosis have enabled even more accurate and effective equipment maintenance. The ideal preventive maintenance program would prevent all equipment failure before it occurs.

Value of Preventive Maintenance

There are multiple misconceptions about preventive maintenance. One such misconception is that PM is unduly costly. This logic dictates that it would cost more for regularly scheduled downtime and maintenance than it would normally cost to operate equipment until repair is absolutely necessary. This may be true for some components; however, one should compare not only the costs but the long-term benefits and savings associated with preventive maintenance. Without preventive maintenance, for example, costs for lost production time from unscheduled equipment breakdown will be incurred. Also, preventive maintenance will result in savings due to an increase of effective system service life.

Long-term benefits of preventive maintenance include:

• Improved system reliability.
• Decreased cost of replacement.
• Decreased system downtime.
• Better spares inventory management.

Long-term effects and cost comparisons usually favor preventive maintenance over performing maintenance actions only when the system fails.

When Does Preventive Maintenance Make Sense

Preventive maintenance is a logical choice if, and only if, the following two conditions are met:

• Condition 1: The component in question has an increasing failure rate. In other words, the failure rate of the component increases with time, thus implying wear-out. Preventive maintenance of a component that is assumed to have an exponential distribution (which implies a constant failure rate) does not make sense!
  
• Condition 2: The overall cost of the preventive maintenance action must be less than the overall cost of a corrective action. (Note: In the overall cost for a corrective action, one should include ancillary tangible and/or intangible costs, such as downtime costs, loss of production costs, lawsuits over the failure of a safety-critical item, loss of goodwill, etc.)
  

If both of these conditions are met, then preventive maintenance makes sense. Additionally, based on the costs ratios, an optimum time for such action can be easily computed for a single component.

Selection of Bridge Type

Span vs Deck Type

• Up to 20m
  Insitu reinforced concrete.Insitu prestressed post-tensioned concrete.Prestressed pre-tensioned inverted T beams with insitu fill.

• 16m to 30m
  Insitu reinforced concrete voided slab.Insitu prestressed post-tensioned concrete voided slab.Prestressed pre-tensioned M and I beams with insitu slab.Prestressed pre-tensioned box beams with insitu topping.Prestressed post-tensioned beams with insitu slab.Steel beams with insitu slab.

• 30m to 40m
  Prestressed pre-tensioned SY beams with insitu slab.Prestressed pre-tensioned box beams with insitu topping.Prestressed post-tensioned beams with insitu slab.Steel beams with insitu slab.

• 30m to 250m
  Box girder bridges - As the span increases the construction tends to go from 'all concrete' to 'steel box / concrete deck' to 'all steel'.Truss bridges - for spans up to 50m they are generally less economic than plate girders.

• 150m to 350m
  Cable stayed bridges.

• 350m to ????
  Suspension bridges.

Integral Bridge

What is an integral bridge?

Integral bridges are single span or multiple-span bridges with a continuous deck and a movement system composed primarily of abutments supported on flexible piles.

Typical integral bridge is shown below;

In these types of bridges, the road surfaces are continuous from one approach embankment to the other and the abutments are cast integral with the deck. The effect of forces parallel to the bridge longitudinal direction is minimized by designing the abutments and their foundations flexible and less resistant to longitudinal movements of the structure.

Accordingly, the abutments are built shorter to reduce the restraint provided by the backfill soil to the longitudinal movement of the bridge. Only a single row of steel H piles is generally used to provide vertical support to abutments and minor resistance to longitudinal forces.

The connection between the bridge deck and the abutment can be rigid or semi-rigid depending on the detailing of joint reinforcement. Elastomeric bearings are used under each girder at intermediate supports. The reinforced concrete columns at intermediate supports may either be free standing or rigidly connected to a reinforced concrete cap-beam supporting the superstructure. The columns are assumed to be supported either by shallow foundations or deep foundations with two or more rows of piles.