1.2 Foamed concrete (FC)

With incorporation of considerable amount of entrained air (20% to 50%) in concrete, foamed concrete is produced which is a workable, low-density, pumpable, self-levelling, and self-compacting LWC. Foamed concrete is used more as a nonstructural concrete for filling voids in infrastructures, a good thermal insulation, and filler for space in buildings with less increase in the dead load.

#### 1.3 Autoclaved aerated concrete (AAC)

AAC, or also named as autoclaved gas concrete, to which a foaming agent is added, was first produced in 1923 in Sweden and is one of the oldest types of LWC. AAC construction systems were then popular all around the world because of its ease of use.

### 1.4 Structural and nonstructural lightweight concrete

Lightweight aggregate concretes (LWAC) can be used for structural applications, according to the American Concrete Institute (ACI). To be considered as structural lightweight concrete (SLWC), the minimum 28-day compressive strength and maximum density are 17 MPa and 1840 kg/m<sup>3</sup> , respectively. The practical range for the density of SLWC is between 1400 and 1840 kg/m<sup>3</sup> . LWC made of a material with lower densities and higher air voids in the cement paste are considered as nonstructural lightweight concrete (NSLWC) and will most likely be used for its insulation and lower weight properties. LWC with compressive strength less than 17 MPa is also considered as NSLWC. There are several benefits with using LWAC such as improved thermal specifications, better fire resistance, and dead load reduction which results in lower cost of labor, transportation, formworks, etc., especially in precast concrete construction industry. With the reduction of the concrete density, the properties of the concrete change fundamentally. For two specimens of concrete with the same compressive strength, but one made of LWC and the other one made of NWC, the tensile strength, ultimate strains, and shear strengths are all lower in LWC than NWC, while the amount of creep and shrinkage is higher for LWC. LWC are also less stiff than the equivalent NWC. However, there are benefits in using LWC such as reduction in dead load that results in slight reduction in the depth of a beam or slab. It is also observed that the elastic modulus of LWC is lower than the equivalent strength of NWC, but when considering the deflection of a slab or beam, this is counteracted by the reduction in dead load.

In the present chapter after the discussion about the lightweight concrete and its properties, we will study about the compressive strength of LWC and the

1.1 Lightweight aggregate concrete (LWAC)

1.2 Foamed concrete (FC)

Compressive Strength of Concrete

ease of use.

50

1.3 Autoclaved aerated concrete (AAC)

mechanical properties of LWA used in the concrete mixture.

and filler for space in buildings with less increase in the dead load.

1.4 Structural and nonstructural lightweight concrete

strength and maximum density are 17 MPa and 1840 kg/m<sup>3</sup>

There are a variety of lightweight aggregates that can be used in the production of LWAC, such as natural materials, like volcanic pumice, and the thermal-treated natural raw materials like expanded glass, clay, shale, etc. LECA is an example of expanded clay and Poraver is an example of expanded glass aggregates. There are also other types, which are aggregates made of industrial by-products such as fly ash, like Lytag. The final properties of the LWC will depend on the type and

With incorporation of considerable amount of entrained air (20% to 50%) in concrete, foamed concrete is produced which is a workable, low-density, pumpable, self-levelling, and self-compacting LWC. Foamed concrete is used more as a nonstructural concrete for filling voids in infrastructures, a good thermal insulation,

AAC, or also named as autoclaved gas concrete, to which a foaming agent is added, was first produced in 1923 in Sweden and is one of the oldest types of LWC. AAC construction systems were then popular all around the world because of its

Lightweight aggregate concretes (LWAC) can be used for structural applications, according to the American Concrete Institute (ACI). To be considered as structural lightweight concrete (SLWC), the minimum 28-day compressive

made of a material with lower densities and higher air voids in the cement paste are considered as nonstructural lightweight concrete (NSLWC) and will most likely be used for its insulation and lower weight properties. LWC with compressive strength less than 17 MPa is also considered as NSLWC. There are several benefits with using LWAC such as improved thermal specifications, better fire resistance, and dead load reduction which results in lower cost of labor, transportation, formworks, etc., especially in precast concrete construction industry. With the reduction of the concrete density, the properties of the concrete change fundamentally. For two specimens of concrete with the same compressive strength, but one made of LWC and the other one made of NWC, the tensile strength, ultimate strains, and shear strengths are all lower in LWC than NWC, while the amount of creep and shrinkage is higher for LWC. LWC are also less stiff than the equivalent NWC. However, there are benefits in using LWC such as reduction in dead load that results in slight reduction in the depth of a beam or slab. It is also observed that the elastic modulus of LWC is lower than the equivalent strength of NWC, but when considering the deflection of a slab or beam, this is counteracted by the reduction in dead load. In the present chapter after the discussion about the lightweight concrete and

practical range for the density of SLWC is between 1400 and 1840 kg/m<sup>3</sup>

its properties, we will study about the compressive strength of LWC and the

, respectively. The

. LWC

methods for evaluation and prediction of compressive strength of LWC. Further a case study of LWC made of LWA will be conducted and presented for a better understanding of the properties of LWC. In the end the conclusion of the chapter will be drawn.
