The Conco Companies, Author at The Conco Companies

Spotlight

New challenges arise for the concrete contractor due to the growing demand for in-fill projects such as Conco’s current Essex-Elkhorn Court Apartment Homes in San Mateo, CA. The City of San Mateo is part of the Bay Area plan drafted by the Association of Bay Area Governments and the Metropolitan Commission designed to find solutions to meet the growing housing needs of the Bay Area. An integral part of their plan is to locate housing near transportation corridors and jobs. The result of doing this would generate a reduction in greenhouse gas emissions due to a less automobile traffic.

Therefore, more projects being constructed are located next to existing commercial buildings and residential complexes. These in-fill projects pose challenges such as noise, site access, and impact on the surrounding neighborhood.

The Essex-Elkhorn Court Apartment Homes will consist of 197 apartment units and have 125,978 square feet of office space with below grade parking for all. The project is being constructed by Barry Swenson Builder.

The Essex-Elkhorn project is sandwiched adjacent to a hospital, day care center and residential housing. Because of this, special attention had to be taken to lessen the impact of performing the concrete work on the surrounding neighbors including scheduling large concrete pours on weekends during designated hours only and reducing the traffic around the site by limiting mixer truck traffic by pumping concrete from one pump to another. The attached clip shows a time lapsed video for accomplishing one of four mat pours scheduled for the project.

Type of Construction:

3” Thick Mud Slab w/ 2” Thick Protection Slab over waterproofing
30” Thick Below Grade Mat Foundation Slab
Two Levels of Below Grade Parking: 8” thick Post Tensioned slabs
Podium Level at Grade: 11” thick Post Tensioned slab
Exterior Basement Walls: Shotcrete applied against shoring walls.
Interior Walls: Shotcrete with Backform
Cast-in-place Columns
Total CY (including mud slabs & shotcrete): 15,500cy

The natural beauty of the Northern California coastline has sometimes wreaked havoc on the coastal communities of Moss Beach and Montara. During the rainy season, mud slides become a frequent occurrence often leading to the shutdown of Highway 1, the only artery leading north to San Francisco.

The resolution to this problem was to build a tunnel through the mountain that will bypass the parts of the coastline most prone to erosion. Public input from local residents reflected a high level of concern that the fix not detract from the natural beauty of the California coastline. Therefore, great attention was made to make sure the tunnel blended in with its surroundings.

Robert T. Hill & Associates, a well-respected artistic firm with 25 of years experience in concrete sculpture, teamed up with Conco on this high profile project. The task at hand was to reconstruct boulder formations out of concrete to blend into the natural formation that existed above the Portal at the south end of the tunnel.

The project was designed by Cal Trans in 2006, but not started until March 1, 2012. Applying shotcrete was extremely difficult as the grade was at 1 to 1 ½ slope. This required the use of man lifts and cranes and sometimes having crews tied off from the top and rappelling down from the top.

The tunnel is scheduled to open in late 2012 before the start of the next rainy season. As a testament to the work from Conco and Robert T. Hill & Associates, the work performed blends into the hillside making it virtually impossible to distinguish between the rocks made by nature and those made by man.

Solution

A city’s history can be told by its venerable buildings that still stand. Over time even the best built buildings succumb to time and stress. Some buildings are worth saving, but cost prohibitive. Retrofit construction costs can often exceed a budget and doom a building. The Hall of Justice renovation project in Los Angeles could have been halted if a cost-effective solution was not designed.

Massive strengthening was necessary to save the 1925-built Hall of Justice. New 24-inch thick shear walls, hammerhead-shaped boundary elements, and drag beams were critical pieces needed to save the ailing structure. These new concrete members will be joined to the existing structure by anchoring approximately 52,000 drill and epoxied dowels.

Conventional methods of placing this concrete would require that forms be erected, adding both time and cost to the project. Additional hurdles would include form material storage, and crew movement through the thirteen building levels. With all of this complexity, it became apparent that pneumatically placed concrete, also known as shotcrete, was the ideal placing method. Shotcrete will allow the construction team to almost eliminate the forming process all together. Once the reinforcing has been installed, the shotcrete can be placed. Furthermore, because shotcrete is placed without a form there are no concrete consolidation surprises.

The Hall of Justice’s structural retrofit would not have been economically possible without the use of shotcrete. Conco’s efforts during the design, its ability to execute, its robust tool set, and immense experience may have given The Hall a new lease on life. Contact us for more information on how we can save or improve your next project.

Follow the progress of The Hall of Justice at CalrkHallofJustice.com.

Looking for a Faster, Economical Solution?

A new parking structure being constructed in Santa Clara, CA offered challenges similar to many other projects. The owner and the general contractor, Devcon Construction, were looking for ways to get the structure built more quickly and economically. One solution used was to build the 40 feet shear walls using the shotcrete method as opposed to being cast in place.

The project, Lawson Lane Commons, has shear walls spanning 310 lineal feet and 40 feet high. Foundations for the walls were poured on 5/25/2012 and three separate shotcrete pours were done with the final shoot being completed on 6/28/2012. In total, 390 cubic yards of concrete were shot and the walls were completed in only 25 working days.

In reviewing this project, our estimators projected that comparable cast-in-place walls would have taken 24% more man hours to complete. The additional man hours would have equated to higher labor costs and several more days on the schedule to complete the task. By using shotcrete provided by Conco, the general contractor was able to have the shear walls completed in less time than anticipated, saving time on the overall schedule. Furthermore, the shotcrete walls have the same structural characteristics as traditional cast-in-place walls.

Do you need to set up a pump in a lane closure and feel your only option is a trailer pump?

Next time order our 17M Special. The “17 Special” needs only an 11’-8” wide footprint with the outriggers fully extended, making it the perfect piece of equipment when pouring from a lane closure or other tight access spot.

Are you placing concrete inside a building with limited height access?

Conco has a series of specialty pumps that can be unfolded in low clearance sites such as inside a building or tunnel or underneath an overpass. The “Z” Boom and “H” Boom technology found on many of our pumps requires less clearance than older “roll and fold” models. Depending on the application, our pumps have been deployed in areas with vertical clearance as low as 13 feet!

Do you need that extra long reach?

Conco operates pumps with boom up to 58 meters (175 feet). We have also routinely pumped concrete long distances (over 3000 feet) under challenging conditions. When you have a difficult material placement, consult with your Conco Sales Professional to help you come up with a cost-effective, safe solution.

Newer Posts

Older Posts