* Q2 OIBD 734 mln eur vs Rtrs poll avg 725 mln
* HeidelbergCement sticks with 2013 outlook
* Says 2013 capex may exceed target to reach 1.35 bln eur (Adds H1 investments, comment on capex outlook, details on demand)
FRANKFURT, July 31 (Reuters) - HeidelbergCement on Wednesday posted a better-than-expected second-quarter operating profit as it managed to increase prices in its main markets.
Operating income before depreciation (OIBD) for the quarter to June rose 6 percent to 734 million euros ($972.62 million), beating average expectations of 725 million euros in a Reuters poll.
HeidelbergCement said an increase in demand in Asian and African markets, as well as in North America, helped offset a slowdown in construction activity in Europe due to flooding.
The company invested more in the first half of the year and now expects its 2013 capital expenditures may reach 1.35 billion euros, compared with its target of 1.1 billion.
HeidelbergCement bought the shares in Russian cement maker CJSC Construction Materials and UK building materials firm Midland Quarry Products it did not yet own. It also raised its stake in Cement Australia, the country's largest cement maker, to 50 percent from 25 percent in March.
HeidelbergCement stuck to its 2013 outlook for an increase in revenue and operating income as well as a marked improvement in pretax profit.
$1 = 0.7547 euros Reporting By Natalia Drozdiak; Editing by Harro ten Wolde and David Cowell