Will there be any competition amongst cement retailers?
Since they are different retailers, their products are not perfectly homogeneous. The differences might be in delivery times, friendliness of representatives, packaging etc. So, their products are not strictly identical.

For the monopolistic competition, it is mentioned that there are multiple retailers. If we assume they do not collude, there will be a form of competition. 

Taking these two characteristics, I would say there is a form of competition, more specifically "Differentiated Bertrand Competition".