Sandy High School. Sandy, OR

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1 Sandy, OR

2 Technical Information Project Completion Date: August Project Location: Bell Street, Sandy, OR Size of Project: 310,000 sq. ft., 8,500 cu. yds. Concrete Strength Requirements: 4,000 psi Water/Cement Ratios: depending on the mix used Total LEED Points Attributed to Concrete Construction: LEED Gold Status Unique Mix Designs: For the ready mix concrete a special architectural wall mix was designed with adjusted ratios of fine to coarse aggregates and water reducers, so that form boards would release cleanly. Both mid and high range water reducers were used to produce the desired results from the 9 slump concrete. Custom aggregates and a color pigment were used in the precast panels. All the precast panels were acid etched or sandblasted to expose the aggregates.

3 Placement Challenges or Unique Techniques: Pea gravel mixes were utilized on the slab on metal deck placements, allowing the contractor to run smaller diameter pump hose and ease the placement process. The large spread out nature of the project required careful communication about access roads and pump placements. The precast panels on the north elevation had 8" returns on each panel. The insulation in the panels "tracked" around the returns of each panel, resulting in continuous insulation along the entire perimeter. Also, the lower stone formliner was completely custom. The precast supplier and architect created four separate molds to give the panels a random look across the elevation. Other Special Technical Aspects: Deliveries were made challenging by the 35 minute travel time to Sandy, Oregon, required that the supplier incorporate set-delaying admixtures to assure that the concrete remained workable for certain placements. The precast panels were load bearing and insulated. Once the panels were erected, all the contractor had to do was caulk the joints to finish the wall system. The architect also designed a redundant precast joint detail that flexed as the panels "breathed" throughout the year. The joints were also insulated to complete the continuously insulated wall system.

4 The growing city of Sandy was in need of a new high school. The original 160,000 SF high was severely outdated and overcrowded. In the fall of 2012 a new, state of the art, 310,000SF facility was opened to the public.

5 The new high school is designed to house a minimum of 1,600 students with support space for an additional 200.

6 It also boasts a gym with seating for 1,800 and a Performing Arts Center with stadium seating for 500. In addition to being a showpiece for the community of Sandy, the project was recently featured in Architectural Record Magazine and also achieved LEED Gold Status.

7 The design and construction teams had a challenge fitting the building on the existing site. The building is situated on a hillside and the elevation grade drops 90 feet from one end of the building to the other. Underground concrete cisterns were placed under the building to control runoff. The cisterns were key sustainable design elements as they helped control rainwater runoff and reduced on-campus water needs.

8 Concrete was chosen early on as durable material for this type of project. Approximately 10,700 CY of cast-in-place concrete was used for footings, foundation walls, slab on grade and slab on deck construction.

9 A form liner was used on the concrete foundation walls to create a board-formed appearance. This was done to complement similar features on the exterior facade.

10 Precast concrete also played a large role in the project. Load bearing, insulated precast walls panels were used on part of the exterior wall system. In order to meet stringent energy code requirements the panels contained 4 of edge to edge insulation.

11 The insulated precast panels on the north elevation contained two separate form liners within the same panel.

12 Precast/prestressed hollow core planks were also used to form the lid of the underground concrete cistern.

13 The New Sandy High School is a showpiece for the community and the concrete industry. Concrete s inherent qualities made it the right choice for a durable, long lasting, low maintenance building.