CLC Blocks (Cellular Lightweight Concrete Blocks)
Cellular Lightweight Concrete (CLC) is conventional concrete, where natural aggregate (gravel) is exchanged for the best insulation medium available, namely air, embedded in organic and bio-degradable foam that offers no chemical reaction but solely serves as wrapping material for the air. Consequently CLC behaves, like conventional concrete, in particular concerning curing, hardening and most important “ageing “. CLC infinitely increases its strength by hydration (forming of crystals in cement) as long as exposed to humidity in the atmosphere.
For structural (steel-reinforced) application, CLC is used in densities of 1,200 to 1,400 kg/m³, which, due to the billion of micro-sized and uniform air bubbles offer 500 % more thermal insulation and a substantially higher fire-rating than conventional concrete. If a wall of conventional concrete should offer the same thermal insulation as CLC, the wall produced would have to measure 5 times thicker and therefore also use 10 times more material (sand, gravel, cement) to produce. CLC structures in hot climatic zones require only 1/5th energy for air-conditioning when compared to traditional clay-brick structures
ADVANTAGES of clc:
CLC Blocks cut to custom sizes on site.
- CLC Bricks have excellent compressive strength in excess of regular solid blocks, guarantees min. Compressive strength of 3N/mm2.
- Bending strength is 15 to 20% of compressive strength.
- CLC Bricks density is 900kg/m2 which reduce dead load on structures.
- Huge saving in foundation and structure savings up to 30% on beam costs.
- Good earth quake resistance properties.
- Easy handling. Lightweight CLC is easy to transport and stock.
- Faster construction. CLC blocks are easily cut to custom size requirements on size using basic power-tools.
- Huge saving of labour. Faster construction directly relates to reduction in labour requirement.
- CLC Bricks offer highest thermal insulation making cool summers and warm winters.
- Reduced Air conditioning expenses. Air-conditioning energy requirements can be 5 times lower than conventional structures.
- CLC Bricks are fire resistant.
- Non toxic fumes in case of fire.
- Excellent acoustic barrier. More peace of living, No disturbance from your neighbour’s home theatre.
- Highly accurate and smooth walls reduction in plastering.
- Opt for any finish on walls – external plastering, tiling, cladding, internal tiling, dry lining, spray plaster or anything of your choice.
Block Size (mm) Block Size (inches) Approximate Weight/block (kg) No. of Blocks / m3 600*200*225 24*8*9 27 37 600*200*200 24*8*8 24 41 600*200*150 24*8*6 18 55 600*200*100 24*8*4 12 83
- CLC Bricks are available in 3 grade strengths:
Grade A: These are used as load bearing units & have a brick density in the range of 1,200 kg/Cum – 1,800 kg/Cum
Grade B: These are used as non-Load bearing units & have a brick density in the range of 700 – 1,000 kg/Cum.
Grade C: These are used for providing thermal insulation & have a brick density in the range of 400 – 600 kg/Cum.
MINIMUM CONPREHENSIVE STRENGTH N/MM2
Recommended usage of CLC based on density
- Density 300-600 kg/m3: This density is primarily applied for thermal insulation or fire protection. It uses only cement (or little flyash), water and foam and can easily be pumped. Foam generators allow the production of stiff foam for slopes to be applied on roof-tops.
- Density 700-800 kg/m3: Is also used for void-filling, such as an landscaping (above underground construction), to fill voids behind archways and refurbishing of damaged sewerage systems. It is also been used to produce building blocks.
- Density 900-1100 kg/m3: Serves to fore mostly produce blocks and other non-load bearing building elements such as balcony railings, partitions, parapets and fence walls etc.
- Density 1200-1400 kg/m3: Are the most commonly densities for prefab and cast in situ walls, load-bearing and non-load-bearing. It is also successfully used for floorscreeds (sound and insulation plus weight reduction).
- Density 1600-1800 kg/m3: Would be recommended for slabs and other load-bearing building elements where higher strength is obligatory.
Advantages in detail:
- Savings in Raw Material: The tremendous savings described when using CLC are manifold, continuing with substantial savings in raw material (no gravel required), in dead load of high-rise reducing by almost half. Considering that a substantial amount of steel is necessary only to carry the weight of the structure, steel requirement might reduce by hundreds of ton in high rise.
- Considerably Lower Weight: Weight reduction is obvious in transport, where almost double of volume of building material can be produced, it has an impact on craning, where either larger panels can be taken, or the full capacity in span. Alternatively less re-location of the crane is necessary.
- Thermal Insulation: Thermal Insulation increasingly turns to be the most important issue in the planning and construction of buildings. There are many costly ways of insulation on sandwich structure of a wall, adding the one or another rigid insulation material, with a satisfactory result by computation but not always a sound solution in safety, health or environment. The best solution is, to incorporate thermal insulation in the mix of a concrete, such offered in air-cured CLC.
- Fire Protection: The air-embedded in the CLC is also instrumental for the high fire-rating. In 1200 kg/m³ density a 13-14 cm thick wall has a fire endurance of 5 hours. The same delay occurs with a 400 kg/m³ layer of CLC in only 10 cm thickness. CLC is otherwise non-combustible.
- Sound Insulation: Over the efforts to keep on increasing the thermal capacity of building members, other aspects have been neglected, such as sound insulation. Sound is experienced as air-borne or foot-fall sound (impact ). Air-borne it is a rule of density and therefore CLC offers superior protection than very light concrete (ACC). In impact sound it is superior to conventional concrete. Hitting a wall with a hammer, will let you feel the full force on the other side, whilst the air embedded in CLC will not allow the blow to pass through. At the most it will suffer a small dent and thereby prevent any greater damage.
- Insulated Flooring: As the impact force will not transmit, slabs produced of CLC or topped with a layer of CLC floor screen will prevent any sound being noticed in the room below. Walls of CLC will also serve as sound retaining walls on roads or railway tracks therefore, absorbing the sound and preventing it from bouncing to the other side.
- Customisable Physical Properties: Adding fibers to CLC is a further important benefit, increasing bending stress substantially and most of it impact strength. The three dimensional acting fiber (e.g. polypropylene) will further reduce shrinkage, therefore reducing water absorption and increasing strength (up to 25 %. This is appreciated most when producing slender building components.
Comparison between Normal Bricks and CLC Blocks:
Aspect Normal Bricks CLC Blocks Remarks Thickness External 230 mm 200 / 150mm Savings of 13 to 35 % Partition 150mm 100mm Savings of 13 % Mortar Masonry External 0.051m3 /m2 0.011m3 / m2 Saving of 78% Partition 0.02m3 /m2 0.005m3 /m2 Saving of 72% Plastering 12 + 15 mm 8 +10 mm Saving of 33% Dead Load External 601 kg /m2 256/ 206kg /m2 Reduction of 60% Partition 319 kg /m2 148 kg / m2 Reduction of 48% Labor for work 100% 60% Reduction of 40% Quality Normal Superior Satisfied client Ease of Working Chase cutting Difficult Easy Faster Lying Service Driving nail Easy Happy Client Longevity May Detroit with time Gains Strength with time as ordinary concrete Better Durability
Comparison between CLC Blocks and AAC Blocks:
Sl.No Parameters CLClite Blocks AeratedAutoclave concrete (AAC)
Basic Raw Materials & Inputs Sand, Cement, Foaming Compound, Water Cement, Lime, sand, Aeration compound, Fly ash, energy
Production Process & Set up Can be produced at project site using concrete mixer & foam generator Produced only in costly plant equipped with steam boiler & autoclaves
Dry Density 400-600 800 -1000 1200-1800 650 750
Compressive Strength 10 – 15 25 -35 60 -250 40 40
Usage Insulation Partitions Non – load bearing Load Bearing Non – load Bearing blocks Reinforced Panels
Pre cast Block Size at site 500x250x90/190mm
Any shape & size in density range
625x250x100/200mm Not Feasible
Aging Gains strength with age No
Thermal Conductivity 0.098 for 400 Kg/m3
0.151 for 700 Kg/m3
0.238 for 1000 Kg/m3
0132-0.151 for 650 Kg/m3
Sound Insulation Superior Superior
Easy Of Working Can be cut, swan, nailed, drilled as timber Can be cut, swan, nailed, drilled as timber
Eco-friendliness Pollution free process with least: Energy requirement also consumes waste Pollution free process with high energy requirement