Case Studies

Client Program

The intent of this experiment was to show the risks associated with Northern United States climates in the “cold” season of the year. The purpose of this experiment is to show that precast concrete use for structural above grade concrete can eliminate almost all risks associated with the use of cast-in-place. The risks looked at for this experiment were costs of Material, Production Rate, and Overall Labor Hours for Safety Risks.

Why i chose precast for the project

Method • Chose a topic related to the climate that our researchers as a group will be faced with daily for our careers. • Created a questionnaire sent out to multiple companies in the precast and cast-in-place industries. • Received the data from the companies and collected all of the findings. • Put the numbers into our building information model to calculate average individual and model costs, time, and labor hours. • Using those averages and numbers calculated, the change in percent of risk for the model and individual members. • Wind, Curing, and Grouting are not factors in this experiment.

Significant Lessons Learned

The data gathered has strong support for the use of precast methodologies in the cold northern climates. The first graph depicts how much time four major U.S. cities can expect to spend beneath a temperature of 40° Fahrenheit. The cities of Minneapolis, Minnesota, Green Bay, Wisconsin, Chicago, Illinois, and Ann Arbor, Michigan can all expect to hit lows beneath 40°F for at least 50% of the year, which is why this research is so relevant. Cost risk per member of precast under these conditions is roughly 4.5%. This extra cost is added in at the factory when steam is added to the aggregate before the mixing begins. This cost is very miniscule, as research shows some companies don’t even calculate the steam into their fabrication pricing. Meanwhile, CIP research demonstrates that to counter against the temperatures most companies will create enclosures, provide heat, and use a hot mix. Companies calculate the cost by surface area SF and can drastically add up to roughly $10 per SF. Time and labor is equally supportive. From the data collected in this research, it is shown that this temperature range has zero risk on precast installation and work hours. Each member of CIP is at an average of 26.55% increase in risk of time per CY of concrete, which comes from added set up and curing times.

Precast Used

From the data gathered by our research and the numbers calculated, it appears that precast does mitigate virtually most risks associated with cast-in-place structural concrete. The data for cost alone is drastic. Precast methodologies average a 4.5% change in cost per individual member unit while cast-in-place averages 152.75%. This number is averaged out by a rough $10 per SF add on for the cold temperatures. Further more, in the building information model, the precast methodology’s total cost variance is only 3.59% change in pricing while cast-in-place is a startling 207%. For this model, the cost risk difference is 203.41%. For labor and time risk, the data is equally supported. The time variance per unit of precast is 0%. Cast-in-place companies had many time wasting activities such as enclosure set up, heat blankets, and heater mobilization, which added up to 26.75% variance per unit. The BIM models show the risk change for CIP at 25%, while there is still no change for precast under these conditions.