Blog Archives

FUEL CONSUMPTION

Posted by on 23/ 11/ 15

The European Asphalt Pavements Association and Eurobitume report of 2004 entitled Environmental Impacts and Fuel Efficiency of Road Pavements (Beuving et al., 2004) is one of the main sources forming the basis for this section of the present chapter.

Rolling resistance is one of the numerous factors of intense interest when con­sidering the problem of fuel consumption while driving, especially in the context of SMA. Rolling resistance may be defined as the force necessary to move a vehicle along a pavement.

At a constant speed of 80 km/h, approximately 12% of the energy loss (fuel consumption) of a heavy truck is consumed in overcoming the roll­ing resistance; the energy spent on overcoming this resistance equals about 30% of the potential available mechanical power at the engine cranksha...

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TYPES OF PAINT

Posted by on 23/ 11/ 15

Years ago, painters who worked with oil-based paints, lacquers, and varnishes in poorly ventilated spaces didn’t last long in the trade. A serious whiff of the solvents in those products would spin your brain and stagger your feet. Fortunately, most of the paint sold in this country today is water based, which is a lot less hazardous to use and cleans up with soapy water. The best latex paint contains a large amount of acrylic resin. Vinyl acrylic is the second-best choice. Vinyl resin is the least durable option.

Oil-based paints are still around but are mainly used by profes­sional painters. Even among pros, alkyd paints containing synthetic resins have largely replaced oil-based paints...

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Lead Framers (continued)

Posted by on 23/ 11/ 15

Ability to Impart Knowledge to Other Framers

• When teaching someone, start with the basics. Assume nothing. Explain in clear and simple language exactly what the job is, and how it is to be done.

• The easiest way to lead may be to give orders, make demands, and threaten. However, it creates an unsettling atmosphere that is not conducive to a cooperative, self-motivated crew. Request that framers do tasks; do not order them.

• Assume that no framer intentionally does something wrong. Help your crew correct errors and show them how to avoid making them again.

• Treat each framer with respect. His time may be less valuable to the company, but his worth as an individual is equal to yours.

• The words “please" and “thank you" can make a framer feel much better about working for you...

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EARTH RETAINING WALL CLASSIFICATION

Posted by on 23/ 11/ 15

A classification system is an essential part of the description and selection of different earth retaining wall types. Figure 8.1 indicates the many types of walls that are possible.

Earth pressure walls can be classified logically into three categories according to their basic mechanisms of retention, or into three categories based on their source of support. The retention mechanisms include internally stabilized, externally stabilized, and hybrid systems. The sources of support are described as gravity, semigravity, and nongravity.

An externally stabilized system uses a physical structure to hold the retained soil...

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PIPE CAPACITIES

Posted by on 23/ 11/ 15

Have you ever wondered what the capacity of a pipe was? You could do some heavy math to figure out the answer to your question, or you can look at Fig­ure 11.16 for quick solutions to your questions.

WHAT IS THE DISCHARGE OF A GIVEN PIPE SIZE UNDER PRESSURE?

What is the discharge of a given pipe size under pressure? The pressure and flow are both factors to consider. If you assume that you are dealing with a straight pipe that has no bends or valves, I can give you a reference chart to use for answers to your question. Further assume that there will be open flow, with no backpressure, through a pipe with a smoothness rating of C = 100. Refer to Figures 11.17, 11.18, and 11.19 for quick-reference charts.

PIPE CAPACITIES

FIGURE 11.17 ■ Discharge of pipes in gallons per minute.

PIPE CAPACITIES

FIGURE 11...

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Conditional probability approach

Posted by on 23/ 11/ 15

This approach starts with a selection of key components and modes of opera­tion whose states (operational or failure) would decompose the entire system into simple series and/or parallel subsystems for which the reliability or failure probability can be evaluated easily. Then the reliability of the entire system is obtained by combining those of the subsystems using the conditional probability rule as

ps, sys — ps | Fm x ps, m + ps | Fm x pf, m (T.65)

in which ps | and ps | Fm are the conditional system reliabilities given that the

mth component is operational Fm and failed Fm, respectively, and ps, m and pf, m are the reliability and failure probabilities of the mth component, respectively.

Except for very simple and small systems, a nested conditional probability operation is inevitab...

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Materials

Posted by on 23/ 11/ 15

Trim materials include custom-milled hard­woods; softwood boards, molding, and stock caps; MDF (medium-density fiberboard); and polymer moldings that replicate detailed histori­cal styles in lightweight, easy-to-install sections.

CHOOSING TRIM

Because trim is costly (especially hardwood trim), buy it from a local shop that mills its own. That way, you’ll be more likely to get trim that is straight, knot-free, and stored in humidity – and temperature-controlled warehouses. If you’re trying to match existing trim, a local milling shop is also your best bet. You may pay a setup fee but, all in all, the final cost of a room or two of custom trim may be more reasonable than you think.

Stock trim from a lumberyard or home center is often so warped that you must pick through the racks and eyeba...

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Apply the second and third coats

Posted by on 23/ 11/ 15

Drvwall compound must be applied in several thin coats because thick applications tend to shrink and crack. Also, thin coats can be feathered or tapered very gradually so that they’re invisible (or nearly so) after the dry – wall surface is painted. Before applying the second coat, remove any lumps, high spots, or ridges of hardened compound left from the first coat. This can be done with a drywall knife or a pole sander. Be careful not to over­sand, or you could damage the paper face of the drywalk

Apply topping compound over the dimples around the fasteners, just as you did with the first coat. Be even more careful as you level the compound, and use a 10-in. or 12-in. knife. Along seams, apply topping compound with a 5-in. knife, then use a 12-in...

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NAILING AND DRILLING

Posted by on 23/ 11/ 15

Because most trim is light, it is usually nailed up with finish nails, which have slimmer shanks and smaller heads than other nails. Trim-head screws (shown in the photo on p. 90) are often specified when molding is heavy or complex or when trim pieces will be subject to twisting or flexing, as happens with door frames and stair treads.

A finish hammer has a smaller head than a framing hammer and so is easier to control when trying to avoid denting the trim. Stop when the nail head is almost flush with the wood surface; then use a nail set to drive the nail head below the surface. Always set nails before sanding or finishing.

Finish nailers have largely replaced hand nail­ing, because pressure settings can be adjusted so the nail goes just below the surface; thus you don’t have to set the ...

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Managing Your Team

Posted by on 23/ 11/ 15

Construction is a unique industry. It is always changing. Each new job or building has its own individual plan, timetable, and workers to do the job. The economy, local governments, codes, tools, and materials are also constantly changing, creating different work environments. The crew structure has to change, as necessary, to accommodate the particular requirements of a job. To be efficient, the lead framer must be aware of all factors that affect the job, and must be able to work successfully within them.

The management structure of a framing crew can differ from company to company. In some cases, the lead framer is the owner/builder. In larger construction companies, the lead framer may run only the framing crew. Either way, the lead framer leads the framing on the job.

This book is not...

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