Effect of Formwork, Wall Thickness, and Addition of Fly Ash on Concrete Hydration
Advances in Civil Engineering Materials
The use of different forming materials, insulating materials, and stripping times can significantly affect the maturity and hence the strength gain of concrete within forming systems. This information can be vital in determining the stripping time of scaffolding and formwork. In this project, maturity and compression tests were performed on specimens (simulating scaled-down walls) formed using a polyvinyl chloride stay-in-place (SIP) forming system with and without insulation. The findings were then compared to data obtained from walls formed by wood formwork, which is the material typically used in the field. The various parameters studied in this project were wall thickness, type of forming material, insulation, and addition of fly ash. The results indicate that with an increase in wall thickness, the peak temperature and the temperature development index (TDI) increased proportionally. TDI is defined as the area under the temperature-versus-time curve measured from the dormant temperature to the peak temperature. The data show that the proposed TDI was a good indicator of the extent of the hydration reaction, and with further research the relationship between temperature development and strength gain of concrete could be clearly identified. Increases in the peak temperature and TDI were noted in wood forming systems relative to SIP systems and in insulated systems relative to un-insulated systems. The use of fly ash in concrete resulted in a lower temperature peak and TDI and a delay in reaching peak temperature. However, the use of concrete containing fly ash in insulated SIP systems led to a higher TDI than a conventional concrete mix formed in wood forms, indicating better concrete maturity at the same age.
PVC SIP formwork, concrete with fly ash, insulation, maturity
Gupta, R. & Kuder, K. (2014). Effect of formwork, wall thickness, and addition of fly ash on concrete hydration. Advances in Civil Engineering Materials, 3(1), 479-494.