Test Parameters

An overview of possible test parameters is provided in Table 4. Not all param­eters given in Table 4 were tested in this study; as an initial test series reported in this paper, rates of water leakage across a deficient joint were evaluated in relation to simulated wind-driven rain loads (i. e., water deposition rate and pressure differential). The degree of deficiency of the joint was dependent on the degree of joint displacement (i. e., movement in extension) and specific “crack characteristics," such as crack location (adhesion) and crack length. Es­sentially, and as will be discussed in a subsequent section, the size of the crack opening in the deficient joint and through which water might penetrate, is a function of the degree of joint extension and crack length.

However, the notional list of possible test parameters permits considering those results that might be obtained from, for example, testing joints: of differ­ent width and depth (or varying W/D ratios); with backer rods of varying size or type; in compression as opposed to expansion; having different types of cracks

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image262FIG. 8—Front elevation of test specimen showing horizontal joint, location of crack in joint.

TABLE 4—Experimental parameters.

Environmental parameters

1. Water deposition rate

1.6, 3.4, 4.0, 6.0 L/(min-m2)

2. Pressure differential

Static pressure: (0, 75, 150, 500, 1000, 2000 Pa)

Building (fagade) condition

3. Joint characteristics

Cross section type

Single joint

Joint orientation

Linear vert. or horiz. joint

4. Jointing product

Type

Working joint

Joint width

20 mm

Joint depth

15 mm

Backer rod

Yes (25 mm)

5. Movement

Wall movement type

Expansion/Compression

Movement ratio

0 %, 2.5 %, 5 %, 10 %

6. Crack characteristics

Crack condition

Yes/No

Crack location 1

Linear joint

Crack location 2

Adhesion failure

Crack length

No crack, 2, 4, 8, 16 mm

TABLE 5—Rainfall area. a

Flow Rate L/min

L/min-m

(width)

Deposition

Rate

L/(min-m2)

0.088

0.88

1.6

0.187

1.87

3.4

0.22

2.2

4

0.33

3.3

6

aWidth 0.1 m, height 0.55 m

(i. e., adhesive at the interface of the sealant and substrate as compared to a crack along center of joint); and cracks of increased size as compared to that evaluated in this study.

The different water deposition rates to which the specimens were subjected are provided in Table 4 and the corresponding rates of water flow necessary to produce these rates are given in Table 5. On the vertical joint, the “rainfall area,” was the area over which water was deposited to ensure a uniform rate over the crack (i. e., 0.1 m wide by 0.55 m high).