I have found an excellent talk by Levi Bryant on the topic "Object-Oriented Philosophy & Speculative Realism". In the talk Bryant discusses the relationship between Critical Theory (as a form of social constructivism) and Speculative Realism (as a form of materialism) in a way that I really appreciate. He makes the foundations of both "approaches" visible and understandable and also reveals what is the problems with both of them and what can be done. Excellent.
[Here is also a very good lecture by Graham Harman https://www.youtube.com/watch?v=hK-5XOwraQo]