Mass Concrete Pours in Casper, Wyoming

Alcova Dam, 265 feet high and 763 feet long, was finished in 1938 on the North Platte River, and it stands as a reminder of how much concrete the Casper area has asked of its builders. Mass concrete is not only for dams. Any foundation thick enough to hold its own heat can crack from the inside, and those cracks do not show up until the structure is already in service.

We place mass concrete for thick mats, heavy equipment blocks, tower and tank foundations and pile caps. The challenge is thermal: cement generates heat as it hardens, the center of a thick section gets hot, the surface cools faster and the difference creates stress. Controlling that difference is the heart of the plan.

The quantity is large, the pour window is long and a failed placement is expensive. That is why we write the plan before we order the first truck.

Where thick concrete shows up in this metro

The metro's industry produces heavy loads. Refinery and oilfield equipment, tower structures and large storage tanks all need foundations that spread weight and resist overturning. The airport's new control tower, a 157-foot structure, needs a base that carries significant moment. Large tilt-up and metal buildings in the logistics areas sometimes have thick pile caps and pier caps too, and the oilfield country around Salt Creek has its own heavy compressor and pump blocks.

Owners and designers often decide what counts as mass concrete from the thickness and the cement content. Many specifications define it as any section where heat of hydration could cause cracking. When the drawings use that language, we assume a thermal control plan is required. If they do not and the section is thick, we raise the question early. Regular structural frames and walls are covered under our cast-in-place structural concrete work, and thick sections are carved out into their own plan.

The Alcova reservoir holds 184,405 acre-feet behind its dam, a scale of placement few of our jobs will match. Even so, the same physics applies to a pump base. Modern mass work uses sensors, data loggers and written limits, so we do not guess at what the inside of the pour is doing.

Heat, cold and the gap between them

Midwest, Wyoming, has recorded a high of 106 F and a low of minus 42 F, a swing that shows how wide the range of conditions can be in this part of the state. A mass pour in July faces a different problem than one in January. In summer, the concrete starts hot and gets hotter. In winter, the surface can freeze while the core is still warm.

We plan around both. In warm weather, we cool the mix with chilled water or ice, shade the aggregate, and pour at night when possible. In cold weather, we insulate the surface with blankets so it cools slowly, which keeps the temperature difference within the limit. Temperature sensors placed in the core and near the surface give us data during the cure.

Mix, lifts and temperature control

The mix design is the first lever. Lower cement content, supplementary cementitious materials and larger aggregate reduce heat. We work with the ready-mix supplier and the engineer to choose a design that meets strength at the specified age, not necessarily at 28 days. Water-reducing admixtures help keep slump workable while cutting cement.

Placement is in lifts when the section is deep, with timing between lifts that allows vibration to blend the layers. We vibrate carefully to avoid cold joints, and we keep the pour continuous within each lift. Finishing and curing follow right behind. Cooling pipes are rarely needed for the thickness common here, but we can coordinate them if the design calls for them.

Curing is where mass pours are won or lost. Wet burlap and plastic are poor insulators, so we use insulated blankets or formwork left in place. The surface is kept moist, and the removal of insulation is staged so the surface does not shock. Cylinders are cured in the field alongside the structure when the specification asks for it.

A pour that runs for hours

A mass pour can use hundreds of cubic yards in a day, so truck supply and plant output matter. We confirm batch plant capacity, count truck cycle times and plan the pump position and reach. The haul distance to the site affects workability, and long Casper-area hauls call for a retarder or a mix that holds slump.

We plan crew shifts so finishers are rested through the end of the pour, and we line up lighting if the placement runs into evening. Testing is scheduled for the whole duration: slump, temperature, air and cylinders from sampled loads. A backup pump is on call. Our pumping and placement notes explain how we stage the equipment.

Rules, review and records

Mass concrete specifications typically limit the maximum temperature in the section and the maximum difference between core and surface, and they require a thermal control plan before the pour. The engineer or the special inspector reviews that plan, and we follow it. Records of temperature readings are kept and submitted.

The City of Casper requires engineered drawings and plan review for commercial permits, and an issued permit is good for 180 days. Because mass pours depend on weather, we line up inspections and testing early so that a good weather day is not lost to paperwork. For related cold-protection details, see our page on cold-weather concrete. Thick sections for utilities and energy companies often follow owner standards that are stricter than code, and we build to the stricter one.

Plan the pour with us

Send the foundation drawings, the target date and the specification section on mass concrete. We will return a thermal plan, a truck plan and a testing plan.

Questions Owners Ask

What makes concrete mass concrete?

It is concrete in a section thick enough that heat from cement hydration could cause cracking. The threshold depends on the specification and the mix, but sections thicker than about three feet are commonly treated this way. Always check the project specification.

How do you control temperature?

We control the mix temperature, reduce cement content where allowed, insulate the surface and monitor the core. In hot weather, we cool the ingredients and pour at night. In cold weather, we blanket the surface for as long as the plan requires.

Can mass concrete be poured in winter here?

Yes, with care. Winter pours need the subgrade thawed, the formwork protected and the surface insulated. The risk is a big gap between core and surface temperature. We use sensors to confirm that the plan is working.

How long before the foundation can carry load?

That depends on the specification. Mass mixes often gain strength more slowly and may be specified at 56 or 90 days instead of 28. The engineer sets when load can be applied, and we confirm with cylinder breaks.

What if a pour is interrupted?

If the pour stops, the plan has a cold joint procedure. We clean and prepare the surface, wet it as required and resume when the engineer approves. We try to avoid interruptions by staging trucks and a backup pump.

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