Several tests were performed with dry vertical joints for sealing masonry and all the results demonstrate that Massa DunDun has a good mechanical performance, even surpasses the performance of masonry of conventional mortar with filled vertical joints, in several aspects. Some of the areas affected by the use of dry vertical joints are:
Tightness: The vertical dry joints masonry built with Massa DunDun has a tightness performance (resistance to moisture infiltration) superior to that of a conventional masonry with filled joints. The main reason is that the vertical joints communicate the internal and external plasters, creating a path that allows the passage of external moisture to the inner side. This can result in a condition called capillary progression. The absence of vertical joints in the construction method of Massa DunDun leaves a small gap between the outer and the inner plaster, which acts as an insulator and prevents the capillary propagation of the external moisture into the interior.
Resistance to stresses transverse to masonry: Due to its superior adhesion in relation to the conventional mortar adhesion, Massa DunDun results in a masonry that is more resistant to transverse stress than is the case with the use of conventional mortar and filled vertical joints. Massa DunDun walls with dry joints were tested according to NBR 15.575, among others, for aspects related to this type of resistance and exceed both the normative requirements and walls constructed with conventional mortar.
Structural deformation and dilatation accommodation: With the use of conventional mortar in the vertical joints, deformations and horizontal stresses in the same plane of the masonry are accommodated by microcracks in the mortar. In the case of Massa DunDun with the dry vertical joints, a small space (between 1 and 3 mm) is allowed between the blocks. This space is subsequently filled by the masonry plasters and is sufficient to accommodate these tensions and horizontal deformations without impact on the integrity of the masonry.
Soundproofing: The passage of sounds by any element depends on its mass. In this way, any constructive method that reduces the weight of masonry will consequently result in a lower acoustic insulation. Although the impact on soundproofing is practically irrelevant, this is a small disadvantage of the use of dry joints with Massa DunDun. The small reduction in acoustic insulation is practically irrelevant since elements like doors, windows and other openings are the main responsible for the passage of sounds in the current constructions.