(b) Effect of admission. Any admission made, or deemed to be made, by a party pursuant to a request made under this rule is for the purpose of the pending action only and does not constitute an admission by him for any other purpose nor may it be used against him in any other proceeding; and the court, at any time, may allow a party to amend or withdraw any admission on such terms as may be just. Any admission shall be subject to all pertinent objections to admissibility which may be interposed at the trial.
(c) Penalty for unreasonable denial. If a party, after being served with a request under subdivision (a) does not admit and if the party requesting the admission thereafter proves the genuineness of any such paper or document, or the correctness or fairness of representation of any such photograph, or the truth of any such matter of fact, he may move at or immediately following the trial for an order requiring the other party to pay him the reasonable expenses incurred in making such proof, including reasonable attorney's fees. Unless the court finds that there were good reasons for the denial or the refusal otherwise to admit or that the admissions sought were of no substantial importance, the order shall be made irrespective of the result of the action. Upon a trial by jury, the motion for such an order shall be determined by the court outside the presence of the jury.