Structural lightweight concrete

LOW DENSITY STRUCTURAL CONCRETE 

sintagg lightweight aggregates

PHOTO :

precast light weight panels aggregates

         

Litagg-Lightweight aggregates intended for use in structural concrete design  in which prime considerations are reducing the density and thermal insulation of concrete  while maintaining the compressive strength of the concrete

Two general types of lightweight aggregates are  available :

Litagg aggregates prepared by expanding, pelletizing  or sintering products 

1. LECA (expanded clay aggregates/pelletes )

 2. SINTAGG ( Flyash based aggregates/pellets )

 and  Litagg aggregates prepared by processing natural materials, such as nodullar, perlite , vermiculite , pumice .

Litagg  aggregates are  composed majorly of lightweight-cellular and granular inorganic material. Litagg Lightweight aggregates are  tested, and does not contains excessive amounts of deleterious substances; and conforms  to the specified values of organic impurities, aggregate staining, aggregate loss of ignition, clay lumps and friable particles, loose bulk density, compressive strength, drying shrinkage, scaling, and resistance to freeze- thaw cycle

Benefits  :

v Reduces upto  25 - 40% weight of concrete , makes lighter and good strength 

v Allows twice as much volume to be carried during transportation

v Is as easy to install , lower thermal expansion so less movement joints needed;

v Gives 100% improvement in thermal conductivity;

v Is efficiently  fire resistant;

v Offers warmer, safer buildings, substantial savings and

v Greater design opportunities

lightweight clay pellets 

lightweight precast panels 

   

STRUCTURAL LIGHTWEIGHT CONCRETE

WHAT :

Structural lightweight concrete density (unit weight) varies from  (1440 to 1840 kg/m3) compared to normal weight concrete with a density in the range of (2240 to 2400 kg/m3).

For structural applications the concrete strength should be greater than 2500 psi (17.0 MPa). The concrete mixture is made with a lightweight coarse aggregate. In some cases a portion or the entire fine aggregate may be a lightweight product.  

WHY :

The primary use of structural lightweight concrete is to reduce the dead load of a concrete structure, which then allows the structural designer to reduce the size of columns, footings and other load bearing structures.

Structural lightweight concrete mix can be designed to achieve similar strengths as normal weight concrete. The same can be for other mechanical and durability performance requirements. Structural lightweight concrete provides a more efficient strength-to-weight ratio in structural elements.

 In most cases, the marginally higher cost of the lightweight concrete is offset by size reduction of structural elements, less reinforcing steel and reduced volume of concrete, resulting in lower overall cost.

 HOW  :

Lightweight concrete can be manufactured with a combination of fine and coarse lightweight aggregate or coarse light- weight aggregate and normal weight fine aggregate. Complete replacement of normal weight fine aggregate with a light- weight aggregate will decrease the concrete density by approximately (160 kg/m3).

Designs of structural lightweight concrete will not typically serve in an oven-dry environment. Therefore, structural design generally depends  on an equilibrium density i.e, air-dry density the condition in which some moisture is retained within the lightweight concrete.

Equilibrium density is a standardized value intended to represent the approximate density of the in- place concrete when it is in service.

Project specifications should indicate the required equilibrium density of the lightweight concrete.