Water Penetration Test Results for Horizontal Joint
Evidence of water penetration at the horizontal joint is given in Fig. 15 and Fig. 16. A view of water entry along the interior side of the joint is shown in the photo of Fig. 14; water is seen to be pooling on the surface of the interior of the joint but ultimately made its way to the drainage opening. A photo (Fig. 16) at the underside of the joint at the crack location shows the path for water leakage through a crack opening of length 16 mm.
A summary of the results from water penetration tests on the horizontal joint is provided in Fig. 17. In this summary, the degree of water penetration is given in terms of water leakage (L/min) as a function of pressure difference across the test specimen (Pa) for ten test conditions. Results for water leakage for crack lengths of 4, 8, and 16 mm are given at joint displacements varying from 0 to 2 mm (10 % joint width). The range of scale for water leakage rate varies by three orders of magnitude, from a low of ca. 0.0018 L / min used for assessing water leakage across joints with no displacement, to a high of 0.2 L/min for joints having displacements of 2 mm.
Some key observations from water penetration tests on deficient horizontal joints are:
• Water leakage occurs when joints are "closed" (i. e., A = 0); even under low pressure differentials;
• Water leakage is pressure dependent; higher rates of leakage are obtained at higher pressure differences;
• A heightened degree of leakage can occur, up to ca. 1.6 L over a 10 min
500 1000 1500 2000
FIG. 17—Water penetration test results for horizontal joint. Variation in water leakage rates (L/min) in relation to pressure different across specimen (Pa) for joints having crack length deficiencies of 4, 8, and 1 mm and joint displacements (A) of 0, 2.5, 5, and 10 % joint width.
FIG. 18—Variation in water leakage as a function of pressure difference and joint displacement for a joint with crack length of 16 mm (a) results for displacement of 0, 2.5, 5, and 10 % joint width; (b) results for no displacement.
interval; this was estimated from the maximum leakage rates of greater than 0.16 L/min obtained for a crack length of 16 mm and 10 % joint opening at 1 kPa and 2 kPa driving pressures.
• Water leakage rates for a crack length of 16 mm are dependent on the crack opening size.
The final observation is more clearly evident from information provided in Fig. 18; the variation in water leakage as a function of pressure difference across specimen and joint displacements of 0, 2.5, 5, and 10 % are given for a joint having a crack length deficiency of 16 mm. The adjoining Fig. 18(b) provides results for no displacement given that these are not readily apparent from that provided in Fig. 18(a). It is evident that as the crack length increases there is a corresponding increase in the rate of water leakage at the opening. For example, at the 1 kPa pressure difference, there is a ca. fifty-fold increase in water leakage rate between a joint displacement of 2.5 % (0.5 mm) and a closed joint (no displacement), and five-fold increase in leakage rate, for increases in joint displacement from 2.5 % to 5 % and from 5 % to 10 %, respectively.
Additionally it can been seen that for the smaller crack opening sizes (i. e., Д = 0, 2.5, 5 %; 0, 0.5 mm, 1 mm), rates of water entry increase with corresponding increases in pressure difference across the specimen; this suggests that the openings are completely occluded with water and the air pressure is driving water through these openings in increasing amounts and in proportion to the pressure difference. Whereas at the largest crack opening (Д =10%; 2 mm), the leakage rate reaches a maximum at 1 kPa pressure difference (0.162 L/min) and at 2 kPa there is only a small increase in leakage rate as compared to that obtained at 1 kPa (<2% to 0.165 L/min)). This suggests that at 1 kPa pressure level, the maximum leakage rate has been reached for the given water deposition rate and crack opening size; in this instance, the opening is no longer completely occluded with water hence air pressure cannot drive additional water through the opening and no additional rate of entry is possible at these test conditions. Such findings mirror those found for the vertical joint.
At water deposition rates at which the comparatively smaller openings are occluded, the larger openings are less readily filled but nonetheless this may occur intermittently given the erratic nature of water migration over openings. For larger openings, there are likely instances in which these openings will intermittently fill with water and thereafter, these water “plugs” would be ejected by the pressure differential across the opening.