Paper 1: Development of high early strength is desirable to the manufacturers of precast and prestressed concrete units, which often require expensive forms or stress beds. Steam curing accelerates the gain in strength at early ages, but the uncontrolled use of steam may seriously affect the growth in strength at later ages. Paper 2: The discovery that concrete aggregates were not inert but could participate in chemical reactions with certain cement compounds stimulated an international research effort that has resulted in the recognition of several distinct mechanisms by which these reactions may reduce the durability of concrete. Recently, attention has been drawn to a reaction involving the cement alkalies and a type of argillaceous dolomitic limestone.