It has given $300m to Cohen & Steers and $150m to Brookfield.
The $36.7bn pension fund has a further $750m available for publicly-traded real assets to reach its new 2% allocation, which was established last year after carrying out an asset-liability study.
“The other types of investments for the asset class have yet to be determined,” said chief investment officer Dhvani Shah.
“Public REITs are likely to be explored.”
The hiring of Cohen & Steers and Brookfield were the culmination of a request for proposal (RFP) launched in February.
The pension fund approved investments in two direct infrastructure funds, also the result of February’s RFP.
Illinois Municipal Retirement Fund is committing $100m to Oaktree Transportation and Energy Infrastructure Fund, and $100m to Partners Group Direct Infrastructure.
The fund managed by Oaktree Capital Management invests mostly in waste management, airports, power plants, marine terminals and energy-related infrastructure in the US.
The Partners Group fund has a global strategy, targeting existing assets with the potential for improvement, growth or the building of investment platforms.
Assets can include transportation, communications, conventional and renewable power, water, social and waste management.