The project manager for a bridge being built on County Road 5240 has responded to concerns raised by the Missouri Department of Transportation (MoDOT) about whether cold weather concrete specifications were met at the construction site.
Jason Murphey, project manager with Great River Associates, responded to the department’s worries and copies of the correspondence between Murphey and Darin Pryor and Dennis Brady, both MoDOT senior construction inspectors, were given to the Phelps County Commission Tuesday morning.
Last week, Pryor sent an email to Murphey, others at MoDOT, the county commission and Brenneke Construction, LLC, the general contractor, stating the concrete poured for a new center pier cap of the bridge being constructed over Beaver Creek south of Rolla does not comply with the specifications.
Pryor wrote that there was no temperature monitoring equipment on site to demonstrate that the concrete had been protected from freezing.
Brady also wrote an email that he had not received a plan for pouring concrete in cold weather.
Murphey responded this week, saying the specifications do not mention having temperature monitoring equipment and accessories that demonstrate to the engineer that concrete has been protected from freezing at the site.
Additionally, Murphey said the cold weather concrete specifications outlined in section 703.3.10 of the 2011 Missouri Standard Specifications for Highway Construction provided to him was not the full specification.
Murphey also said a cold weather plan was not provided because the forecast called for “decent weather through the weekend for concrete curing.”
The concrete was poured March 8, not March 9, as had previously been stated in one of Pryor’s emails.
This week, Murphey wrote that the ambient temperature for March 8 was 54 degrees Fahrenheit and “there was no curing compound used in the pour.” Murphey also provided MoDOT with temperature highs and lows from March 8 to March 17.
After learning about the cold weather forecasted for the night of March 10, Brenneke was directed to blanket the center pier cap to maintain internal heat. “We feel that the contractor has demonstrated protection from freezing under controlling site conditions by blanketing,” Murphey wrote this week.
Murphey also provided test reports this week to MoDOT from concrete cylinders taken on the site that show the concrete strength. Murphey said the tests conformed to ASTM (American Society for Testing and Materials) and AASHTO (American Association of State Highway and Transportation Officials) testing methods.
“We stand by our determination that the cylinders taken on site following proper sampling and testing procedures provide the closest representation of the concrete poured on the site,” Murphey wrote.
Page 2 of 2 - “The concrete cylinders that were tested confirm that there was no adverse impacts to the concrete strength and that the required strength was achieved,” Murphey wrote.
Murphey wrote if MoDOT does not concur that the standard testing methods can be accepted, he offered two other tests — a nondestructive test called a Windsor probe and a destructive test, which involves specifically coring and looking at crystallization and then performing a compression test on the core.”
Work on the bridge stopped in November after a higher than anticipated slope was noticed on the bridge that was caused when the contractor was building the center pier and used Great River Associates’ plans, which had a discrepancy in the elevations and dimensions.
Brenneke was given a notice to proceed work again Feb. 5. However, because the period of Dec. 15 to March 15 including both those dates and Saturdays, Sundays and holidays established by law are not counted as working days, the days that work took place since Feb. 5 do not count toward the contract.
Working days were counted again starting Monday, March 18. Brenneke informed Murphey that he estimates it will take 18 days to finish the rest of the bridge, as long as MoDOT accepts the concrete poured.
Brenneke’s 18-day estimate includes seven days for repairing slab beams, four days for resetting the grouting beams, three days for installing guardrails and four days to finish the road. Murphey said there are more days left in the contract than the 18 days the contractor estimates the rest of the work to take.