Award: Green Design
Contractor: Donley’s Inc.
Architect: Solomon Cordwell Buenz
Engineer: Magnusson Klemencic Associates
Concrete: Crooked River Materials LLC
Slag Cement: LafargeHolcim
Standing 396 ft (121 m) tall, The Lumen at Playhouse Square is a 34-story glass tower containing 319 residential apartments; built on a 1-acre (0.4 ha) site at the corner of Euclid Avenue and East 17th Street in Cleveland, OH. This apartment tower offers residents commanding views of the City and Lake Erie. The 602,000 ft2 (56,000 m2) project also contains a parking garage that accommodates 528 cars and boasts of 22,000 ft2 (2000 m2) for resident amenities and retail.
The concrete producer delivered 6000, 8000, and 10,000 psi (41, 55, and 69 MPA) concrete that was used to build the cast-in-place concrete structural system, complete with post-tensioned interior floors. All of the concrete contained slag cement replacements between 20 and 40% for purposes ranging from increased strength and durability; to reducing permeability and thermal stresses. In addition, slag cement was employed to create an attractive surface where the concrete’s structural system is viewed as a striking interior element in this beautiful addition to Cleveland’s skyline.
Slag cement was used to reduce thermal stresses in the 6000 psi mat foundation. Although
replacement ranges between 50 to 65% are typically required to achieve temperature differentials between the concrete surface and its interior to prevent thermal cracking, testing revealed that a replacement of 40% proved to be ideal for both strength and reducing thermal stresses. The mixture contained a total cementitious content of 560 lb (254 kg) and yielded 56-day compressive strengths in excess of 7700 psi (53 MPa).
During peak placement, the mat pour surpassed 700 yd3/hour (500 m3/hour). This volume of concrete in such a short time was achieved due to slag cement’s ability to improve the concrete’s rheology. For example, slag cement greatly improved the concrete’s ability to be pumped, and helped eliminate stone pockets and honeycombing, and generally improved the overall placement characteristics of the mat foundation.
Parking garages in a severe weathering climate such as Cleveland are susceptible to the ingress of deicing salts. To enhance the garage’s protection against the migration of chlorides/salts, a slag cement replacement of 20% in all the garage’s post tensioned slabs and beams were all that was necessary to produce favorable rapid chloride permeability results, while yielding average 28-day compressive strengths in excess of 7000 psi (48 MPa).
The design called for apartment ceiling heights ranging between 9 ft-8 in. to 11 ft (3 m to 3.4 m), with very open floor plans allowing for more architectural freedom. The first 16 floors contained 10,000 psi concrete, while the balance of the floors contained 8000 psi concrete. All of the structural columns
and shear walls contained 30% slag cement. The 10,000 psi concrete yielded 56-day compressive strengths well in excess of 11,000 psi (76 MPa).
The interior floors were post-tensioned reinforced concrete. This resulted with thinner concrete sections and longer spans between concrete columns. All of the building was fast-tracked. It was required that the freshly placed interior floors be ready for forming the ensuing floor as soon as possible, and in many cases, the next day. Although concrete containing slag cement at temperatures less than 85°F (29.4°C) can have slower set times than mixtures compared with 100% portland cement; from October to May 6000 psi concrete was delivered with Type III cement. These mixtures contained 640 lb (290 kg) of total cementitious and 22% slag cement, along with a polycarboxylate superplasticizer and set enhancing admixtures, yielded 28-day compressive strengths over 10,000 psi with no delay in set time.
The Lumen at Playhouse Square is the largest residential project undertaken in downtown Cleveland in 40 years. The Lumen was chosen as the building’s name to reflect the energy surrounding Playhouse Square as well as the importance of light in theater in general and the Playhouse Square District in particular: the GE Chandelier, the marquees, retro sign, and gateways.
10,000 psi high-strength columns and shear walls
% Slag Cement Replacement
% Portland Cement
% Other SCM (if applicable)
10,000 to 11,000 psi