I think that, using such materials may reduce strength significantly and using polystyrene blocks is better.

Dear Bala,

Portland cement has heat of hydration of about 65°C so maybe occur that expanded polystyrene can be attacked by this “internal heating”. Usually the dosage of binder can be adjusted to avoid this problem. Of course mechanical properties will be affected when you increase amount of polystyrene and you reduce amount of OPC.

Normally you need to add some wetting agent that permits good mixing if you use only polystyrene as aggregate , because of lightweight . There are already on market all additives to obtain lightweight concretes ,depending on final density you want have and consequently ,depending on performances and thermal insulation you will achieve. BASF and other big manufacturers of polymers have the additives that you need (Defoamers, superplasticizers, foaming agents and so on).

Best regards

Alex Reggiani

Hello

To answer your question clearly can you give information about the type of expanded polystyrene you are using and if possible its properties? Have you obtained it through the supplier? To be precise, it wont react with concrete in lab scale for sure, hope you will be doing short terms studies which may end up in 28 to 56 days.

To obtain more data read this article

Article Durability of Modified Expanded Polystyrene Concrete after D...