Blog Archives

Filter Design

Posted by on 13/ 11/ 15

Pavement structures consist of material layers with different grain size gradations and different mechanical as well as permeability properties. As water will flow through the structure it is important that migration of a portion of the fines from one layer to the next will not take place. To achieve this, the principles of fil – tration/separation must be applied at each interface (Cedergren, 1977). This is of special interest where water flows from fine grained material into a coarser grained material on its way out of the structure.

In applying the filter criteria the material to be drained is frequently referred to as the base material and the new material to be placed against it the filter material. The filter criteria stipulate that the filter needs to fulfil two functions:

• water n...

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STEP 3 BACKFILL AROUND THE FOUNDATION

Posted by on 13/ 11/ 15

Подпись: BUILDING WALLS WITH INSULATED CONCRETE FORMS Insulated concrete forms (known as ICFs) offer builders an easy way to build insulated concrete walls for crawl-space and basement foundations. Made from polystyrene or another rigid foam, these forms are designed to stay in place; they aren't stripped off like standard forms. It doesn't take a lot of building skill to stack these blocks prop-erly. On a recent job in Oregon, we snapped chalklines on the concrete footing to mark where the first course of form blocks would fit. We then started from the corners and laid two courses of blocks to form the crawl-space walls. With four of us working, it took less than two hours to lay the blocks. Polystyrene blocks interlock, so very little extra bracing is need-ed to hold them in place as concrete is poured into them. A horizon-tal 2x4 screwed to the outside or inside of the wall helps hold the forms straight. Drive a stake in the ground every 4 ft. or so, and run a brace between the stake and the horizontal 2x4.This will keep the walls straight throughout the pour.To strengthen the wall and pre-vent the forms from floating up and away, tie together a network of horizontal and vertical rebar, as shown in the photo below. There are some concerns with ICF walls.The foam can offer a hidden pathway for subterranean termites.To avoid this, install a metal termite shield under the sill plate. Also, the foam surface is rather soft and can be easily dented and gouged.To prevent this, cover the outside walls with 2-ft. by 8-ft. fiber-cement panels or stucco. STEP 3 BACKFILL AROUND THE FOUNDATION

The foundation is ready for the floor framing work to begin. But the job site isn’t. Backfilling against the walls restores at least some of the site’s original contour, making it safer and easier to move around. If you’re building a house with a full basement, the backfilling process is usu­ally delayed until after the first floor is framed and sheathed. Because they are taller, basement walls need the extra rigidity provided by the floor framing to ensure that backfilling doesn’t damage the foundation. This isn’t a major concern with crawl-space walls, so it’s good to backfill now. But first, it’s important to take care of the following details.

Termite protection

In areas where termite infestation is possible, some builders elect to call in a licensed pest – control cont...

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Finland

Posted by on 13/ 11/ 15

The requirements for cellulose fibers according to PANK 2000 have been divided into obligatory and recommended ones as follows:

• Obligatory requirements

• Water content according to PANK 3103: < 8.0% (m/m),

• Instantaneous heat resistance (mass loss) according to PANK 3104: < 7.0% (m/m)

• Recommended values for bulk fibers

• Bulk density according to PANK 3105: 20-35 g/dm3

• Homogeneity according to PANK 3107: 2.0-2.8%

• Fibers’ length distribution:

– 80% value: 1.2-1.9 mm

– 50% value: 0.5-0.9 mm

• Specific surface area according to PANK 2401: 2.0-3.0 m2/g

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Coordination of Horizontal and Vertical Alignments

Posted by on 13/ 11/ 15

When designing new roadway projects, the following items should be considered to

coordinate the horizontal and vertical alignments:

• Curvature and tangent sections should be properly balanced. Normally, horizontal curves will be longer than vertical curves.

• It is generally more pleasing to the driver when vertical curvature can be superimposed on horizontal curvature. In other words, the PIs (points of intersection) of both the vertical and horizontal curves should be near the same station or location.

• Sharp horizontal curves should not be introduced at or near the top of a pro­nounced crest vertical curve or at or near the low point of a pronounced sag vertical

curve.

TABLE 2...

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United States

Posted by on 13/ 11/ 15

The United States is one of the few countries where requirements for cellulose fibers and mineral stabilizing agents have been standardized. Some other countries have adopted the U. S. requirements in their own specifications.

The requirements for cellulose and mineral fiber SMA stabilizers after AASHTO MP-8-05 include the following: [22]

• Shot (nonfibrous material) content

• Passing 0.25-mm sieve: 90% ± 5%

• Passing 0.063-mm sieve: 70% ± 10%

• Ash content of cellulose fibers: 18% ± 5% nonvolatiles

• pH of cellulose fibers: 7.5 ± 1.0

• Oil absorption of cellulose fibers: 5.0 ± 1.0 times fiber mass

• Moisture content of cellulose fibers: maximum 5% (m/m)

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A Tricky Victorian

Posted by on 13/ 11/ 15

This two-family Victorian house (circa 1860) was difficult to upgrade because we weren’t allowed to remove siding, replace the win­dows, or dig into the slate roof.

The historic commission did, however, allow us to remove and replace the siding and windows on one wall where the siding was damaged and needed replacement, so we injected open-cell foam, added house – wrap and furring strips, and replaced the siding on that wall.

Historic commissions all over the country favor historical authenticity over durability and energy efficiency with regard

 

Tar-paper baffle connects wall and roof insulation.

 

Kneewall

 

Drywall is a code-required fire block.

 

3/4-in. furring strips

Wood

siding

 

Open-cell spray foam (R-40 in the rafters; – R-14...

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Requirements for stabilizers

Posted by on 13/ 11/ 15

Specifying the desired properties of stabilizers is a troublesome task, which is why there are not very many examples of formalized requirements for them. In fact, detailed testing of a stabilizer’s properties is practically impossible in the asphalt plant laboratory. Therefore, in many countries, testing is limited to draindown check­ing (i. e., only an empirical assessment of stabilizer effectiveness).

A few examples of standardized regulations come from Germany and the United States. Some requirements were also in the Finnish specification PANK 2000.

5.3.1 Germany

The requirements adopted in Germany were cited in a 1997 document entitled

Testing and Marking Stabilizing Additives and Materials Applied for Bituminous

TABLE 5.7

POLAND

SLOVAKIA

GERMANY

SWEDEN
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Procedures to Prevent Insect and Rodent Infestation

Posted by on 13/ 11/ 15

Some simple measures can be applied from the outset of construction that will prevent infes­tation of rodents and insects. Consider adding the following requirements to the above list:

• All foodstuffs shall be disposed of in con­tainers that will be removed from the jobsite and emptied at the end of each workday.

• All debris shall be removed from under and around the building premises and properly disposed of in a Dumpster. The Dumpster shall be removed when full on a regular basis so that piles of debris do not accumulate on the ground around it.

Quality Control

There may be some instances where you will be asked by your contractor to share in the re­sponsibility for application of an experimen­tal material. You may choose to accept this responsibility on a case-by-case basis...

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FRAMING

Posted by on 13/ 11/ 15

This chapter illustrates the basic sequence for floor framing. Straight cuts and tight nailing make for a neat and professional job. Pay particular attention to the corners. It is important that they stay square and plumb up from the walls below, so the building does not gain or lose in size. Also pay close attention to laying the first sheet of subfloor sheathing. If it is laid straight and square, the entire subfloor will go down easily and you can avoid making extra cuts.

If you make a sloppy start on the first sheet, you’ll struggle to make each sheet fit, you’ll waste valuable time, and you won’t be proud of the results.

FRAMINGStep 1-Crown & Place Joists

Spread joists so crowns are in the same direction. The crown is the highest point of a curved piece of lumber.

If the joists are resting ...

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Factors Affecting Permeability

Posted by on 13/ 11/ 15

Predicting the saturated permeability of soils or aggregates based on theoretical con­siderations has turned out to be difficult as permeability is dependent on a number of factors such as grading, void ratio, soil texture and structure, density and water tem­perature (Cedergren, 1977). Therefore, several empirical equations for estimating the permeability have been proposed in the past. These equations frequently include parameters linked to the grading curve of the material or their void ratio.

Hazen (1911) proposed an equation of the permeability of loose clean filter sand as:

K = cD2l0 (2.22)

where c is a constant that varies from 1.0 to 1.5 when the permeability K is in cm/s and the effective size D10 is in mm...

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