The first phase of construction for the colossal One Thousand One mixed-use development in Hawthorne (Philadelphia), Pennsylvania (USA), was completed in July 2024. PENETRON ADMIX SB, a crystalline concrete waterproofing admixture, was chosen to provide durable concrete swimming pool and deck structures, which are constantly exposed to chlorinated water.
A revitalized neighborhood in the South Philadelphia section of Philadelphia, Hawthorne features an increasingly youthful demographic and many streets undergoing renovation of the historic housing stock. The One Thousand One multi-use development in Hawthorne spans an entire city block at the intersection of South Broad Street and Washington Avenue.
Designed by the BKV Group, a national engineering company, and Nelson Worldwide, a national design and architecture firm, the mid-rise residential / commercial development covers an area of 1,516,218 ft2 (137,840 m2). A series of “L” shaped 14-floor towers bisect the site into four quadrants, providing space for 1,111 apartment units, a 15,000 ft2 office building, over 65,000 ft2 of ground floor retail space, which includes a 40,000 ft2 Giant Supermarket, and a parking garage.
“The first phase of construction comprised the completion of 600 apartments and 50,000 ft2 of commercial space,” explains Richard Farmer, Regional Sales Manager for Penetron USA. “The next phases, set for final completion by 2026, will further add 511 apartments and 15,000 ft2 of commercial space.”
Post Brothers Construction, the general contractor, required a robust waterproofing solution for the 3rd-floor swimming pool and deck, which were poured using normal weight concrete. Elevated concrete pool and deck designs, like the One Thousand One project, have successfully utilized PENETRON ADMIX SB as a waterproofing solution in many previous projects. Silvi Materials supplied the concrete mix treated with PENETRON ADMIX SB, a permeability reducing admixture, to waterproof the pool and deck concrete.
Post Brothers Construction collaborated with Penetron to explore different waterproofing solutions, resulting in the adoption of a unique strategy. Castor Materials, the ready-mix concrete supplier responsible for the lightweight concrete segment, incorporated PENETRON ADMIX SB into their mix design.
“This novel way of treating the elevated decks accelerated the dry-in of the lightweight concrete and construction in various critical areas. In turn, the upper elevated floors then provided temporary waterproofing protection for the lower floors,” adds Richard Farmer. “By speeding up this stage of the project, the new occupants were able to move in earlier at Broad & Washington.”
PENETRON ADMIX SB was mixed into 3,500 yds3 of concrete used for the swimming pool and deck structures. Added to the concrete mix in pre-measured soluble bags during the batching stage, PENETRON ADMIX SB is formulated to react with moisture to produce an integral crystalline formation throughout the concrete matrix. This makes the concrete impermeable to water, liquids, and waterborne elements, extending the service life of the concrete structures.
“Thanks to tests carried out during the One Thousand One project’s early concrete pours, we were able to verify that PENETRON ADMIX SB does not negatively impact the performance of the mix or the process of pouring the lightweight and normal weight concrete mixes,” added Richard Farmer. “The Post Brothers team was happy with the performance of the concrete mixes that were delivered for this project.”
