EPS Reinforced Concrete - Fascinating Walling Material

The essential characteristic of lightweight EPS-reinforced concrete is its porosity, which results in low apparent specific gravity. In concrete construction, self-weight represents a substantial portion of the load on the structure, and there are considerable advantages in reducing the density of concrete. Furthermore, lightweight concrete improves construction and handling techniques; larger units are often desirable; transportation and on-site handling would be more economical.

Lightweight concrete reduces the cost of formwork and steel and it also increases productivity. It is giving better thermal insulation than ordinary concrete. The practical range of densities of lightweight concrete is between about 300 and 1850 kg/m³.

Polyconcrete is lightweight concrete made with cellular polystyrene beads “particles” as aggregate. Unlike aerated concrete, which requires autoclaving to obtain both lightness and strength. It can be used for both in-site and pre-cast components. The lightweight aggregate can be made at the concrete works, using raw expandable polystyrene beads. Since polystyrene particles are uniform and relatively coarse, the structure can range from that of no-lined concrete (density 300 kg/m³ or less) to that of fully compact concrete (density 1000 kg/m³ or more).

Table of Contents

Composition of EPS-Crete

Sand (150 – 700 kg/m³)
Ordinary Portland Cement (Fly ash up to 10% of cement weight) 200 – 600 kg/m³
Water/ cement ratio – 0.35 – 0.45
Expanded Polystyrene beads 3 – 8 mm coated with latex paint – 0.3-1.2 m3/m³
Air bubbles of coarse size (1-3mm dia.)

Characteristics of EPS-Crete

Light weight – reduces self-weight of the building
Fire retardant property
Good energy-absorbing properties
High acoustic resistance
High thermal resistivity
Eco-friendly – no pollution to the environment
Low energy consumption
EPS – recyclable
Cost-effective
Wide density range (300 – 1800 kg/m³)

Polystyrene Beads – Characteristics

Extremely light, with a density of 12 to 20 kg/m3 when compared to that of concrete aggregates (1700-2000 kg/m3)
Hydrophobic – Surface treatment is needed
The bond between EPS beads and cement paste needs additional bonding additives
The thermal conductivity of Polystyrene is very low.
Aged polystyrene can be classified as a “flame retardant”.
Prone to chemical attacks.
Expanded Polystyrene beads are non-absorbent since their cells are closed.
They are easily compressible.

Structural Application

Cladding panels
Curtain walls
Composite flooring systems
Load-bearing concrete blocks
Sub-base material for pavement
The protective layer of a structure for impact resistance

Properties	Advantages	Disadvantages
Weight	Light; down to 600kg/m³
Strength	Ranging from 2 to 20 N/mm²
Resistance to chemicals		Sensitive to most petroleum products
Field Applications	Suitable for Structural and non-structural members	Not suitable to be used as prestressed concrete
Cost	Less than most available lightweight concretes
Acoustic resistance	The best among all other lightweight concrete
Fire Resistance	Burning without flames	Starts to evaporate above 300 C
Workability	Very workable at a low w/c ratio
Mix consistency	Consistency for w/c 0.32 to 0.45	Stable for up to 30 minutes after mixing
Thermal insulation	The best among all other lightweight concrete
Hardening time of fresh concrete	Less than normal concrete

Admixtures

Admixtures modify the properties of Polyconcrete in the same way as those of normal dense concrete. However, special caution is necessary with accelerators and retarders, since the higher temperatures in fresh Polyconcrete can enhance their effects: if not adequately tested, or added in the wrong proportions, such admixtures can result in useless mixes. The most effective and economical method of increasing the strength of Polyconcrete is to raise the proportion of cement. However, this entails an increase in density and may cause increased drying shrinkage.

Manufacture – Insite

To ensure that the mixture is as homogeneous as possible, it is important not only to correctly select the ratio of binder, fillers and additives but also the sequence of loading into the drum.

Loading polystyrene foamed granulated, pouring a small amount of water (1/10 part) with modifiers.
Stirring the contents (30-60 seconds), so that the granules are moistened.
The introduction of cement (and sand, if we are talking about heat-insulating structural and structural EPS concrete)
Introduction of water (8/10 parts) with a modifier.
The introduction of the rest of the water with the air-entraining admixture diluted in it (finished foaming agents, liquid soap, dishwashing agents)
Stirring the solution for 3-5 minutes until a homogeneous, workable mixture is obtained.

It is common to pour a monolith into a removable or non-removable formwork, a pit, as well as pouring screeds, rough floors and creating heat insulation contours. Since granules and pores are weak protection from shrinkage and cracking, it is recommended to use fibre as a reinforcing additive if these phenomena are critical for the design.

Conclusion

The new lightweight concrete consisting of polystyrene, sand, cement and water has been proven that the proposed mix is very reliable giving strengths of up to 200 kg/cm2 with a low density. The mechanical and chemical properties have, also, been discussed in order to study the behaviour of polystyrene under different environments (i.e. field usage). The mix workability is very high at a very low water/cement ratio (down to 0.35).

A new method for designing Polyconcrete mixes has been introduced in a simple, yet practical and tangible way. The mixing method of lightweight concrete is very simple, relatively inexpensive and does not need complex machinery systems. It is recommended that further work should be done to cover; permeability, structural behaviour, absorption, freeze and thaw durability, abrasion, and corrosion of steel reinforcements. The use of Polyconcrete is essential to be as structural members.

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