In concrete, certain plasticizers can increase the workability time by how long?

Using plasticizers in concrete significantly improves the mix's workability, allowing for easier handling and placement during construction. The addition of plasticizers can extend the workability time by preventing the mixture from setting too quickly, which is particularly beneficial in warmer weather or when working with larger pours.

The typical range for the extension of workability time due to plasticizers generally falls within 30 to 60 minutes. This timeframe allows contractors to work efficiently without the concrete hardening too quickly, ensuring that they can pour and finish the concrete as required before it begins to set. This increased workability is crucial for achieving a good finish and preventing defects in the hardened concrete.

Options suggesting shorter or significantly longer workability periods, while they may have scenarios of application under specific conditions, do not typically represent the standard range observed in practice. Therefore, the selection of 30 - 60 minutes as the appropriate answer aligns well with practical applications of plasticizers and their effects on concrete mixing and placement.