Ultra-Light-Weight Concrete:
The density of ultra-light-weight concrete varies from 600 kg/m3 to 1000 kg/m3. It is made up from a mixture of cement, sand and expanded-polystyrene beads (1 mm to 6 mm in diameter). This concrete is commonly used for pre-fabricated non-load bearing panels, solid blocks and hollow, and in highway construction as a part of sub-base where frost could endanger the stability of the sub-grade. This concrete has high thermal insulation efficiency. The expanded bead products may be treated with bromine solutions for improving the fire resistance and self-extinguishing characteristics. The expanded beads have density about 12 kg/m3 to 25 kg/m3. The commonly used size of expanded beads is about 1 mm to 3 mm. The beads deteriorate producing a characteristic yellowing when uncovered to sunlight. The expanded-polystyrene concrete mixes can be designed to have compressive strengths up to 15 MPa to 20 MPa. The expanded-polystyrene beads become electro-statically charged during processing which makes them difficult to wet during mixing. Proneness to segregation could be overcome through using a bonding agent controlling the fluidity of the paste. Thermal insulation and compressive strength properties of expanded-polystyrene concrete increase with its density. The setting and hardening rates can be controlled by selecting the suitable cement and using water-reducing admixtures. Conventional methods can be used for casting and placing the expanded-polystyrene concrete. The elastic and shrinkage deformations are considerably greater than for normal-weight concrete. The conventional workability tests, i.e. slump test, Vee-Bee test, flow table test and compacting factor test are unsuitable in case of expanded polystyrene concrete.