Water penetration in cracked clay brick masonry before and after repointing

This research study investigates the response of clay brick masonry with different crack widths before and after repointing subjected to water spray. In doing so, 3-course masonry prisms containing artificial cracks were exposed to a water spray during 23 hours of testing. Forty-nine cracked 3-course masonry prisms were prepared with a crack width varying between 0.3 mm and 0.9 mm, whereas thirteen specimens were built without known cracks for comparison. The results indicate a reasonable correlation between the crack width and the average water penetration rate. Compared to the reference specimens, those with crack widths of 0.3, 0.5, 0.7, and 0.9 mm showed average water penetration rates of 1.7, 2.4, 3.0, and 5.1 times higher, respectively. Further, a strong correlation was observed between the saturation level and the start of water penetration. In the reference specimens, water penetration started when the water content reached above 90% of the saturation capacity. Depending on the crack width, water penetration in the cracked specimens started when the saturation level was between 72 – 87%. The specimens were repointed and once again exposed to water spray. On average, the water penetration rate decreased by around 54% in the reference specimens and between 47 – 74% in the specimens with cracks. Raking of the specimens during repointing revealed that many head joints contained voids and gaps, confirming that head joints are probably the weakest part of clay brick masonry concerning water penetration. The results show that repointing has the potential to significantly reduce water penetration in clay brick masonry with and without known cracks exposed to water spraying.