In a trading update, the London-listed group said that the acquisitions of May Gurney and Mouchel have given Kier's long-term prospects a boost, and that its property division has a pipeline worth over £1bn.
"The EU referendum result has created some uncertainty albeit with no impact on the business to date.
"The board, however, believes the group's breadth of activities and strong order books provide both visibility and resilience," the firm said.
However, bosses at Kier have ordered a strategic review of its underperforming operations and have made £53m worth of provisions linked to its Caribbean division and its consulting arm.
Kier said: "A review has been undertaken of those operations which do not meet the group's strict financial hurdles andor do not provide a long-term strategic fit with the group's core businesses."
City analysts predict that sales for the full year will increase 37% to £4.5bn and pre-tax profits are set to rise 47% to £126.5m.