ASP.NET access value from Dictionary and format it and add value again in dictionary

   FormatResolvedHrsMins = Convert.ToString(keyValueCollection["ResolvedHrs"]) + ":" + Convert.ToString(keyValueCollection["ResolvedMin"]);
                KeyValuePair<string, object> ExpectedClosure = new KeyValuePair<string, object>("ExpectedClosure", FormatResolvedHrsMins);
                keyValueCollection.Add(ExpectedClosure);