Focus Area

Lightweight Concrete (LWC)

Lightweight concrete (LWC) has a maximum density of 2000 kg/m3 and is achieved by using low-density aggregates. Intermediate-density concretes, where part or all the normal-density coarse aggregates are replaced with structural-grade low-density aggregates, have densities of 1450 kg/m3. The main advantage LWC can offer is to reduce the dead load of a concrete structure, which then allows the structural designer to reduce the size of column, footings and other load bearing elements, LWC mixtures can be designed to achieve similar strength as normal weight concrete. LWC is particularly suitable for bridge abutments because it does not impose large lateral loads, which can be problematic when using traditional granular materials, due to sideways pressure against the bridge walls caused by the materials used and their compaction. It can also find application in fire and corrosion protection, covering for architectural purposes, heat insulation on roofs, insulation of water pipes, gilling for floor and roof slabs, and construction of partition walls, panel walls in framed structures and production precast building blocks and low cost housing. Additionally, ultra-Lightweight Concrete consist of a category where densities less than 1100 kg/m3 and compressive strengths less than 7 MPa are achieved. These concretes include expanded or other very low density aggregates, such as expanded polystyrene, perlite, blast-furnace slag and vermiculite and rubber particles.

Cellular Lightweight Concrete (CLC)

Cellular lightweight concrete (CLC) is produced through controlled introduction of air into the concrete. In CLC the air is incorporated in form of a foam (produced by protein or surfactants) which is then mixed with the concrete or cement paste. Through this procedure the density of CLC can be adjusted to values between 2000 and 250 kg/m3. CLC is decreasing its mechanical performance with the decrease in density (increase in porosity: 0.1-1 mm). It is generally self-levelling, self-compacting and may be pumped. It is used for insulating fills, conduit linings, fire walls and non-structural panels. In order to take advantage of the physical properties of the lightweight CLC, such as acoustic and thermal insulation, and to mitigate the weak mechanical performance, CLC can be combined with a more structural material, such as Fiber Reinforced Polymer (FRP) reinforcing bars.

Lightweight conventional and advanced ceramics

Lightweight ceramic components containing a large volume of designed porosity possess a rather exceptional array of properties, besides displaying the typical favorable characteristics of ceramics, such as wear resistance, refractoriness and chemical inertness. In fact, they have low density, thermal conductivity, dielectric constant, thermal mass and, simultaneously, high specific strength, permeability, thermal shock resistance, and specific surface area. Namely, foam ceramics have fine pore size, excellent stability and high integrity, being as light as < 323 kg/m3 and with use temperatures as high as > 1700οC. Their unique combination of properties allows them to significantly extend the range of materials properties, and makes them suitable for a wide range of advanced applications. These include filtration, radiant burners, catalyst supports, biomedical devices, kiln furniture, reinforcement for metal matrix composites, bioreactors, thermal protection systems, components in solid oxide fuel cells, lightweight structures, heat exchangers, ablative structures, etc. Moreover, most of the oxide and non-oxide ceramics and ceramic matrix composites have excellent mechanical properties including hardness and mechanical strength, but they do not present enough dynamic strength. To increase density and dynamic strength a common technique that is used is spark plasma sintering, aiming to high tech applications, including automotive and aerospace applications, ballistic armor, electronics, thermal insulators and engine components. In particular, the densities of SiBCN (2.56 g/cm3) and SiC (3.29 g/cm3) are considerably less than that of Al2O3 (3.98 g/cm3), targeting mainly to defence and aerospace applications. .