Goal: Optimize the performance-durability relationship of the standards concrete mixes used at RMP.
Key Materials: Fly Ash Class “C”, new generation of Polycarboxylate High Range Water Reducer (SHRWR).
Benefits: Due to its chemical and mechanical properties, fly ash can improve plastic
and hardened concrete while reducing cost and CO2 emissions. Some of the
advantages of fly ash in plastic concrete are:
Reduction in water demand.
Improved workability.
Reduced bleeding.
Reduced segregation.
Reduced bug holes.
Some of the advantages of fly ash in hardened concrete are:
Contributes to strength.
Reduced permeability.
Increased durability.
Program:
A comprehensive test program was designed to gradually modify the concrete mixture materials and proportions necessary to obtain the optimum flowing and engineering properties. The program was divided in 2 stages.
- Laboratory Phase. A mathematical relationship between the strength, slump and various mixture proportions variables was developed, then a series of trial batches were carried out.
- Field Phase. Based on the results from the laboratory trials, a more elaborated testing scheme was undertaken to obtain the necessary data to satisfy the ACI 214 and 301 qualification requirements for compressive strength.
Facts.
Laboratory Testing: February 2004
Trial batches: July 2004
Implementation: September 2004
Average f’c of mix 1A (f’c=5000 psi) from September to date: 7816 psi
Average f’c of mix 2A (f’c=6000 psi) from September to date: 8242 psi
Average f’c of mix 3A (f’c=6500 psi) from September to date: 8242 psi
