DUBLIN (Reuters) – U.S. cement maker Ash Grove Cement Co ( ASHG.PK ) said it had received a takeover proposal valued at up to $3.8 billion, surpassing an earlier offer from Irish building materials firm CRH Plc ( CRH.I ).

Ash Grove said the new bid, from an unnamed party, was valued at $3.7-$3.8 billion and was expected to result in a superior offer.

Shares in CRH, which said last month it agreed to buy Ash Grove for a total consideration of $3.5 billion, were down 1.6 percent on the news at 30.96 euros.

Ash Grove has set a meeting on Nov. 1 for shareholders to vote on the agreement with CRH and has extended its go-shop period during which it can look for other potential buyers to Oct. 20, the cement company said in a statement.

Responding to the rival offer, CRH said on Friday its proposal remains in place, subject to the approval from Ash Grove shareholders.

Ash Grove is the fifth largest cement manufacturer in the U.S. where it has operated eight cement plants in as many states under the same family for over a century.

CRH, which is already North America’s biggest maker of concrete products and second largest supplier of aggregate materials for construction, said it wanted to acquire Ash Grove to add extensive readymixed concrete, aggregates and logistics assets across the U.S. midwest.

“The emergence of an eleventh hour bidder… is perhaps not surprising given Ash Grove’s attractive position in the US cement market,” said Davy Stockbrokers analyst Robert Gardiner, but he said CRH had little choice but to wait for Ash Grove to evaluate the proposal before deciding whether to improve its offer.