The Constructor

Heavyweight Aggregates for Production of Heavyweight Concrete

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Heavyweight aggregates as it can be seen from the name is an aggregate that posses relatively high density and it is fundamental in a situation that high density concrete is necessary. Generally, aggregates with specific gravity of 2400 Kg/m3 and higher are considered to be heavyweight. The concrete density that can be obtained based on the aggregate type for example, concrete density would be 3900 Kg/m3, which is about 60 percent higher than normal concrete density when Magnetite is used, the concrete density would be around 3500 Kg/m3 when Barite is used that is greater by 45 percent compared with normal concrete density. Moreover, extremely heavy concrete could be produced by employing steel aggregate. There are different types of minerals in composition of the heavyweight aggregate which includes either synthetic or natural. The compositions of natural mineral aggregates are dominated by minerals like magnetite, hematite, serpentine, ilmenite, and barite. Examples of synthetic aggregates include steel, iron, boron frit, Ferrophosphorus. Furthermore, coarse heavy aggregate consisting of crushed ore, synthetic products or mixtures of both while fine heavy aggregate consists of high density minerals and manufactured or natural sand. Additionally, high density grout and mortar can be achieved when it is needed by using fine heavy aggregate. Table 1 Provide specific gravity and composition for different types of heavyweight aggregate:

Properties of Heavyweight Aggregates

Table 1 Physical properties, chemical composition of different class of heavyweight aggregate
No. Material class Predominant constituents Granular bulk density (Kg/m3) Chemical composition essential minerals
1 crushed stone, hydrous iron ore Limonite 2100 to 2400 (HFeO2)x(H2O)y
2 crushed stone, hydrous iron ore Goethite 2100 to 2250 HFeO2
3 gravel or crushed stone Barite 2300 to 2250 BaSO4
4 crushed stone, iron ore Ilmenite 2250 to 2700 FeTiO3
5 crushed stone, iron ore Hematite 2900 to 3200 Fe2O3
6 crushed stone, iron ore Magnetite 2400 to 3050 FeFe2O4
7 Synthetic (Scrap steel) Steel 3700 to 4650 Fe
8 synthetic Ferrophosphorus 3200 to 4150 FenP

Specifications of Heavyweight Aggregate:

Advantages of Heavyweight Aggregates

Properties of heavyweight aggregates which are desirable for producing heavyweight concrete are:

Application of Heavyweight Aggregate:

There different and numbers of applications of heavyweight aggregates. Since heavyweight aggregates are the main and most important constituents of heavyweight concrete, it would be much clearer and easier to understand the importance of this type of aggregate through heavyweight concrete application. Various applications of heavyweight aggregate are as follows: 1. Radiation Shielding that includes nuclear or shelter bomb or medical as shown in Figure 1 , offshore structure, ballasting. Gamma and x-ray are two types of radiation that should be taken into account during designing for concrete radiation shield, see Table 2. Table 2 some aggregates that recommended for radiation shield.
Types of aggregate Granular bulk density (Kg/m3) Shielding capability
Goethite 2100 to 2250 Fast neutrons
Limonite 2100 to 2400 Fast neutrons
Barite 2300 to 2250 Gamma rays
Ferrophosphorus 3200 to 4150 Gamma rays
Boron Frit 2600 to 2800 Neutrons

Figure: Heavyweight concrete that produced from hematite aggregates used to construct of floors, ceiling, and walls in order to guarantee full radiation shielding for medical building

2. Counter weights 3. Application in which high mass to volume ratio is required 4. It might be useful to attenuate vibration and sound.
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