Insulite blocks are made primarily from a mixture of cement and polystyrene beads using technology patented in Lebanon and the US. The mixing operation is very important to ensure a good distribution of the different substances while preventing segregation.

Different types of blocks can be fabricated from this mix, each with its own special shape and application.

Strength

Insulite blocks are strong and light. The strength and the density attained are 1,200 psi (84 kg/sq cm) and 1,200 kg/cu m respectively.

Figure 1.

Figure 1(1) shows the relationship between compressive strengh, density and cement factor. Being a light Styropor concrete mix, the moulding of large blocks becomes feasible, while the costs of handling, hauling, and laying are largely reduced.

Thermal & water-vapour resistance

The blocks offer high thermal and water vapour resistance as heat transfer in Styropor concrete is mainly restricted to conduction through the cement mortar surrounding the cellular beads. The thermal conductivity is relatively low, even at higher densities. The mortar, being rich in cement, also offers fairly high resistance to diffusion of water vapour, this providing high values of relative vapour resistance.

Figure 2.

Figure 2(3) shows a general range for concrete's thermal conductivity as a function of unit weight. Although actual conductivities depend on the particular aggregate used and the concrete's moisture content, these generally increase exponentially with unit weight. Figure 3 (1) shows the relationship of thermal conductivity versus density for polystyrene-concrete. A comparison between Figures 2 and 3 shows that normalweight concrete has a thermal conductivity of approximately 15 Btu in/hr sq ft deg F - about eight to 10 times more than that of the 60 pcf (density) concrete. With such high insulating properties, Insulite blocks used in external walls and roofs will contribute to large savings in energy bills.

Figure 3.

Incombustible and fire resistant

The Institute for Bautechnik in Germany has certified that polystyrene-concrete of density 600 kg/cu m or more is classified as an A2 (nichtbrennbar) building material in accordance with the Erganzende Bestimmungen to DIN 4102 (2).

The fire resistance of Insulite blocks is dramatically improved by filling them with normal concrete.

Waterproof

Insulite blocks and panels, made of a rich cement mix and a large volumetric percentage of polystyrene beads, develop a matrix of beads fully entrapped in a slurry of cement which is highly impermeable. Furthermore, polystyrene beads are naturally resistant to water.

Soundproof

The structure of a polystyrene bead, once expanded, is a series of noninterconnected air cells clustered in such a way to form the sphere of a bead, thus giving a very low air porosity. The rich slurry fully covers the beads and keeps them separated. Consequently, on account of its density and porosity, such masonry material becomes a good sound insulator. The mean soundreduction index of a partition constructed from 100 mm Polystyrene-concrete of density 600 kg/cu m and covered on both sides with 15mm lime plaster has been found to be 40 dB(2).

Polystyrene-concrete normally has a rough surface, and this gives moderate sound absorption. However, it was observed that the sound absorption coefficient did improve significantly when exposed beads were removed by heating the surface of hardened concrete

Saving in materials

The use of large Insulite filler blocks, or Insulitehourdi blocks, will cut down the volume of concrete in all slabs by at least 24 per cent. Moreover, if Insulite Hourdi blocks are used in all slabs and Insulite blocks are used in all partition walls, the dead weight of a building will drop by at least 26 per cent. Such a large reduction in the total weight will affect the size of the foundation and will yield a total saving in material of between 30 and 35 per cent.

The light weight of Insulite Hourdi blocks allows the moulding of a large block equivalent in size to two regular Hourdi blocks, while its weight is two and a half times less.

Ease of use & economy

Due to their lightness and interlocking properties, Insulite blocks and panels can be easily handled and laid quickly. They weigh 2.5 times less than the equivalent concretesand blocks. A mason can therefore lay more square metres per hour with half the help.

The light weight of the Insulite blocks allows a flatbed truck to transport almost twice the number of Insulite as compared to regular cementitious blocks. Also, the process of loading and unloading becomes much simpler and more economical.

Due to the small volume of aggregates used in the mix, the process of cutting an Insulite element to fit a given dimension or shape is very simple and easy. A saw or a disc can provide a smooth surface for any cut required.

Interlocking Insulite blocks - even if laid without mortar - fit tightly against each other to the extent that a whole wall, up to a height of 1 m, rocks as one piece. Therefore, only a small amount of mortar is required between blocks, resulting in savings of time and material. In earthquake-prone areas, interlocking Insulite blocks can be used as permanent formwork. Reinforcing bars can be laid horizontally and vertically and the wall, up to 3 m high, can be concreted in one pour and connected to the columns and to the slabs, enhancing the three-dimensional strength of the building.

1. Styropor for Lightweight Concrete, BASF, technical Bulletin S-5, 1988;

2. Styropor-concrete: technology, properties and applications. Bu Gunter Baum, BASF Aktiengesellschaft 1974;

3. An Introduction to Lightweight Concrete, by Martha VanGeem, Construction Technology Laboratories.