Improvement of the waterproofing technology of cast-in-situ foundations with dry sprinkling

The study of waterproofing technology for cast-in-situ reinforced concrete foundations with the “dry sprinkling method” which is a cost-effective and efficient alternative to traditional solutions using rolled materials is performed. Despite its use in the Soviet Union, the dry sprinkling method remains understudied and rarely applied in modern civil construction. The study aimed to experimentally validate the effectiveness of dry sprinkling waterproofing technology for cast-in-situ foundation structures. The laboratory tests were carried out on three experimental slab models with varying reinforcement densities using a domestic cement-based powder mixture to evaluate the water resistance of the concrete slab layer. The results demonstrate that by achieving sufficiently uniform distribution of the dry mixture within the volume of the slab’s bottom protective concrete layer it is possible to significantly improve the water resistance grade of this concrete layer at the reinforcement pitch of 100 mm, as well as compliance with certain technological requirements. During the experiments, low process reliability was identified in the existing dry sprinkling waterproofing technology operations. The issues were primarily related to uneven distribution of the dry powder mixture over the blinding concrete surface and its settling on reinforcing bars. To address these shortcomings, a device for uniform powder distribution was developed and patented. Economic calculations confirmed the cost efficiency of the dry sprinkling waterproofing method for cast-in-situ foundations, showing up to 40% savings compared to traditional two-layer roll waterproofing applied on the concrete footing. The obtained results justify the feasibility of large-scale implementation of the dry sprinkling waterproofing method for cast-in-situ foundations, subject to specific technological requirements.