Blog Archives

PRESSURE-TREATED LUMBER

Posted by on 12/ 11/ 15

In areas where the termites are especially hungry (Hawaii and some southern states), entire house frames can be built of pressure – treated wood. Pressure-treatment technology was developed to repel termites and inhibit rot, and it does so effectively. During the treatment process, a preservative compound is forced under pres­sure into raw lumber, penetrating deeply into each board.

For many years the main ingredient used in treated wood was arsenic. A dangerous poison, arsenic was effective in repelling termites but also harmed the workers who manufactured and used these construction materials. The EPA eventually banned the use of arsenic in PT wood, and suppliers replaced the arsenic with copper and other less harmful chemicals...

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TESTING METHODS FOR STABILIZERS

Posted by on 12/ 11/ 15

Despite the great impact of the stabilizer on SMA quality, few countries have devel­oped testing methods and criteria for the practicality of stabilizers. Some assess­ment methods for the application of stabilizers in various countries are presented in Chapter 5.

Practice proves that a reliable stabilizer-effectiveness assessment can be carried out when the same SMA mixture (the same JMF*) is tested with different stabiliz­ers. Comparison of test results from tests on different SMA mixtures is unreliable. The results of one test will not be comparable with the those of the others because the results for each mixture depend on the SMA composition, such as the type of aggregate and binder contents.

A direct method of checking the effectiveness of stabilization (i. e...

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Durability and Energy Efficiency Are Intertwined

Posted by on 12/ 11/ 15

Making a flooded basement livable is a great example of how one type of repair is directly related to another. On one of these projects, we needed to stop water from leaking into

the old rubble foundation with a perimeter drain and a new slab. Adding insulation under the slab and inside the walls keeps the space free of condensation and also saves energy.

The durability and functional upgrades illustrated on the following pages cost a lot. By spending a bit more, we were able to reduce energy costs tremendously. After cutting energy consumption, the stage is set for the installation of affordable, renewable power sources to offset the remaining energy needs. And that 21st-century step could transform these vintage homes to net-zero energy houses or even energy producers.

Durability and Energy Efficiency Are Intertwined3-in...

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PROPER SELECTION OF THE AMOUNT OF A STABILIZER IN A MIX

Posted by on 12/ 11/ 15

The procedure for the quantitative selection of a stabilizer in a mix is simple, although it may be a little laborious. One of the draindown testing methods described in Chapter 8 may be adopted here. A series of SMA samples of the same composition should be prepared, but with different quantities of stabilizer. If the procedure is carried out with a proven product (e. g., cellulose fibers), testing may be limited to 0.2%, 0.3%, and 0.4% (m/m). If it is a product that has not yet been used, the testing series ought to cover a somewhat wider range based on the expected behavior (e. g., 0.1%, 0.2%, 0.3%,

0. 4%, and 0.5% [m/m]). Draindown should be determined for each stabilizer content, and the results should be plotted as shown in Figure 4.10...

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FORMULAS FOR PIPE FITTERS

Posted by on 12/ 11/ 15

P

lumbing and pipe fitting are similar, but not always the same. Modern plumbers usually work with copper tubing and various forms of plastic piping. Cast-iron pipe is still encountered, and steel pipe is used for gas work. Finding a plumber working with threaded joints is not nearly as com­mon as it once was. But, threaded pipe is still used in plumbing, and it is used frequently in pipe fitting. Figuring the fit for a pipe where threads are to be inserted into a fitting is a little different from sliding copper or plastic pipe into a hub fitting. However, many of the calculations used with threaded pipe apply to other types of pipe.

Many plumbers don’t spend a lot of time using mathematical functions to figure offsets. Heck, I’m one of them...

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Techniques USING A HAMMER

Posted by on 12/ 11/ 15

Techniques USING A HAMMERTechniques USING A HAMMERПодпись: NAILING WITH A HAMMERПодпись: Drive nails with a fluid stroke, involving shoulder, arm, and wrist action. . •Подпись: Wrap your thumb around the handle.Подпись: The hammer face needs to strike the nail head flat.Подпись: Driving nails is sort of like swinging a tennis racket. Your grip on the handle should be secure but relaxed, and thp swing should involve your entire arm and wrist.Techniques USING A HAMMER

JUST LIKE HITTING A SOLID-LINE DRIVE or

delivering a blazing tennis serve, driving nails quickly and accurately takes time and practice to master. Like most athletic endeavors, efficient nailing has at least as much to do with rhythm and coordination as it does with power and force. Learn to nail using your entire body; make a fluid shoulder, elbow, and forearm movement that ends with a decisive snap of the wrist (see the illustration at right). Practice your tech­nique. Grasp the handle near the end with an easy, firm grip, making sure your thumb is wrapped around it. Buy a box of 8d or 16d framing nails, find a hunk of wood, and start driving nails. In time, you’ll be amazed at the speed and force with which you can drive nails.

When pulling nails with a wooden-handled hammer, hook the...

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Techniques READING A TAPE MEASURE

Posted by on 12/ 11/ 15

Techniques READING A TAPE MEASURETechniques READING A TAPE MEASURE

A MEASURING TAPE IS SIMPLY a long ruler in a convenient easy-to-use package. Just like a ruler, a tape is laid out in feet, inches, and fractions of inches. Knowing how to read a tape quickly and accurately is an essential skill for anyone involved in the building trades.

The key to being able to read a tape is learning and understanding all the subdivisions of an inch (see the illustration at right). Each inch is divided into halves, quarters, eighths, and sixteenths. Once you can discern the mean­ing of all these little marks, you’ll have no problem measuring 13 ft., 9}/is in., or any other odd dimension. Study the drawing and your own tape until you can rattle off accurate readings at a glance.

In addition to feet and inches, a tape also has special marks at 16 in., 32 in...

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Binder Viscosity Promoters

Posted by on 12/ 11/ 15

The second way to counteract the draindown phenomena is to use a binder viscos­ity promoter. The most common agents used to be polymers, either plastomers or elastomers. Test results show, however, that the efficiency of polymers is not as good as that of fibers. Currently in many countries, regardless of the type of applied binder (modified or paving grade), fiber stabilizers are required. Binder modified with special materials may be considered, except for polymers directly metered into a pugmill at an asphalt plant. Polymer stabilizers also have a higher viscosity over the preferred range of production temperatures...

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SLIDING COMPOUND-MITER SAW

Posted by on 12/ 11/ 15

A 10-in. sliding compound-miter saw is the ulti­mate tool for a wide range of finish work. The extended crosscut length, combined with adjustable angle and bevel settings, allows com­plicated cuts in larger materials such as 6-in. by 6-in. deck posts, 10-in.-wide siding boards, and large crown molding.

POWER PLANERS

Moderately priced and incredibly useful, a power planer can plane down studs to create a flat plane for drywall, trim a little off an exterior door, and quickly cut a slot so the nailing flange of an elec­trical box is flush to the edge of a stud (see the photo on p. 167).

RIGHT-ANGLE DRILL

Renting a h-in. right-angle drill will let you avoid burning out your own drill while roughing in plumbing and electrical runs...

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Conditional probability

Posted by on 12/ 11/ 15

The conditional probability is the probability that a conditional event would occur. The conditional probability P (A | B) can be computed as

P(AI B) = PAA <2.6)

in which P (A | B) is the occurrence probability of event A given that event B has occurred. It represents a reevaluation of the occurrence probability of event A in the light of the information that event B has occurred. Intuitively, A and B are two independent events if and only if P (A | B) = P (A). In many cases it is convenient to compute the joint probability P (A, B) by

P (A, B) = P (B) P (A | B) or P (A, B) = P (A) P (B | A)

Подпись: P Conditional probability Подпись: P (Ai) x P (A2 | Ai) x P (A3 | A2, Ai) x- ■ ■ x P ( AK | AK-1,..., A2, Ai) (2.7)

The probability of the joint occurrence of K dependent events can be general­ized as

Example 2.3 Referring to Example 2...

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