The effect of MWCNTs on the structure of lightweight porous composite

Abstract

The problem of reusing or recycling disposed packing tare of expanded polystyrene is relevant in the world. Due to an inert, closed-cell and ultra-light (up to 95% air by volume) and non-water absorbing structure, expanded polystyrene and its aggregates are widely used as packaging materials for many types of goods. However, once the material is used, it is disposed in landfills, where it can remain intact for several generations. Low density (15 kg/m3 ) and thermal conductivity coefficient of 0.042 (W/(m·K)) make it possible to use expanded polystyrene aggregates in different formulations of composite materials. The main objective of this study was to carry out more detailed research on the effects of the amount of MWCNTs on the physical and mechanical properties of porous fine aggregate composite based on different fineness crushed expanded polystyrene. The crushed expanded polystyrene aggregates (household packaging), made of local waste, ordinary Portland cement (OPC), plasticizing, air-entraining and MWCNTs (0.00005–0.5% bwoc) admixtures, as well as pozzolanic additive – metakaolinbased waste, were used for the preparation of composite mixtures. The addition of MWCNTs (0.005% bwoc) in interaction with plasticizing and air-entraining admixtures increases the cement stone open porosity, promotes a fine-pore structure and due to the reinforcing effect increases the compressive strength. After 28 days of hardening, the compressive strength and open porosity of cement stone increased by 13.6% and 5%, whereas density decreased by 11%. When different fineness crushed expanded polystyrene was used in composition, the density and compressive strength vary within 830–310 kg/m3 and 6.5–0.7 MPa range.