Comparison Hollow Concrete and Fly Ash

Masonry is applied since ancient time as well as till date it holds the acceptance. It is supposed to be the strongest as well as most durable during the course of the world. In the previous times, stones were extensively used as a masonry unit. Nevertheless in the contemporary time, bricks are one of the greatest extensively applied building materials in the construction trade. As masonry units, these bricks are widespread particularly thru developing countries since they are economical, tough, and easy to handle as well as easy to work with. Switch the flip side, they ensure some drawbacks as well. Clay, which is the chief raw material of the orthodox brick, is found from the dirt of the earth’s surface but on account of the incessant and quick manufacturing of bricks, the fertile topsoil is vanished. Thus, the deficiency of such topsoil decreases the accessibility of agricultural land. Additionally, during its built-up the harmful CO2 gas is released which is an environmental threat. Therefore, the orthodox bricks are not measured as an environment-friendly masonry component. Thus, it becomes vital and indispensable to find a better substitute for orthodox bricks. These days, fly ash bricks and hollow concrete blocks are gaining popularity as effective alternatives to sand.

Both of them are suitable possibilities for conventional bricks. The evaluation in this article will support you pick the accurate masonry unit for your home building. 

Hollow Concrete Blocks vs. Fly Ash Bricks

01. General

• As per a study ‘Hollow concrete blocks possess one or additional large holes or else cavities which either go through the block (open cavity) or else do not commendably pass through the block (locked cavity). They hold the solid material between 50 as well as 75 % of the entire volume of the block intended from the overall magnitudes. These holes or cavities decrease the whole cross-sectional area in addition to volume of the block.

• Fly ash bricks are recyclable bricks which are prepared using fly ash or else pulverized fuel ash. They are likewise known as pulverised fuel ash – lime bricks. They are in fact 100% solid as well as they do not possess any cavity contrasting to Hollow Concrete Blocks.

02. Actual Raw Material

• Hollow concrete blocks contain a combination of cement, sand, aggregates or gravel along with water. Sometimes industrial waste similar to fly ash, bottom ash etc. is as well used in their built-up.

• Fly ash bricks are prepared from the combination of fly ash or else pulverized fuel ash, sand, cement, lime in addition to gypsum.

03. Application

• Hollow concrete blocks are employed in all kinds of masonry construction for example,
  a. Outward load-bearing walls
  b. Internal load-bearing walls
  c. Curtain walls
  d. Partition wall as well as panel walls
  e. Support to stone, brick, in addition to other facing
  f. Fireproofing above a structural member
  g. Fire-safe walls nearby elevators as well as stairwells
  h. Piers, column, retaining walls etc.

• Fly ash bricks are used in a variety of construction types for load-bearing and non-load-bearing walls due to their strength and durability. They are similarly employed for other purposes for instance,
  a. Raising Infrastructures
  b. Warehouse
  c. Factories
  d. Power plant
  e. High rise buildings etc.
  f. Erection of pavements
  g. Tanks, below water works
  h. Waterway lining
  i. Irrigation work

04. Benefits

• One of the significant benefits of hollow concrete block is its high strength as well as less weight. Therefore, there is less dead load which eventually keeps reinforcement steel in RCC building.
• Hollow concrete blocks masonry is a simple and quicker construction practice associated with any other conservative masonry practices.
• These hollow blocks are environment- friendly since industrial wastes similar to fly ash or bottom ash are utilized as the raw material.
• The hollow blocks deliver comfortable interiors because of thermal insulation.
• The hollow blocks possess a rough texture which enables them in imparting a decent bonding between cement mortar as well as blocks.
• A semi-skilled worker can also work by hollow concrete blocks.
• Hollow blocks are first class sound insulator.

• They are moreover good earthquake resilient.

• Water absorption of hollow blocks is moderately less as compared to fly ash bricks.
• Since blocks are bigger in size, there is obviously less number of joints. And hence, mortar consumption is a smaller amount.
• Reinforcing through steel is also possible through hollow concrete blocks.
• The concrete blocks are lighter in weight therefore, easy to lift. Likewise, steel required is less because of less dead load.
• These concrete blocks can be applied in the building of load-bearing structure equal to 6 storeys by means of steel.
• Since steel is used there is in fact less dead load. Accordingly, hollow concrete reinforced masonry buildings have healthier earthquake resistant.
• Exceptional hollow concrete blocks can too put up horizontal reinforcements with the intention of horizontal beams for example lintels as well as horizontally reinforced reinforced concrete bands can be constructed with these blocks.

05. Drawbacks

• Hollow blocks are poor heat insulator since they have less thermal mass.
• As associated with fly ash bricks, hollow concrete blocks are costly for the erection of a house. Nonetheless, it depends upon the rate at which it is accessible in the local market.
• It is not simple to install hidden wiring in hollow concrete block masonry.
• Diverse sizes of blocks are mandatory and factory-made for lintel, sill, in addition to jamb.
• Fly ash bricks have a low mechanical strength, however this strength can be increased by inserting marble debris or mortar between the blocks.
• There is restrictions to its size. Merely modular size can be contrived. Manufacturing the big size will lead to additional breakages.
• Since this brick lack the heat absorbing ability, it is suggested for the subtropical region or mainly for the regions where the weather is warm. It is not much cooperative in the cold regions or else even throughout winter season.
• They are actually heavy in weight associated with hollow block.
• Hidden wiring is likely in this masonry work.
• It is not promising to employ steel in fly ash brick masonry work.