Laser Screed VS Conventional Placement

The construction of high quality, durable flat slabs has long been known to be a critical element in the in the life, serviceability and productivity of industrial facilities. From logistics warehouses, workshops and factories, day in day out, no other single element faces more demands than the floor.

As such, floor construction has faced more scrutiny placing higher demands on contractors to place floors which meet the long term facility requirements for productivity, reduced maintenance costs and planned service life.  In meeting these requirements contractors have traditionally relied on two methods of floor construction:

  1. Conventional “long strip” placement
  2. Laser screed “large bay” placement

In this case study we will undertake a review of both processes to help developers/contractors better understand the costs and benefits of both systems.

Conventional “long strip” Construction:

Strip construction consists of placing and finishing slabs in narrow panels of widths of 5-6m in most cases and lengths of 25-30m. Width is generally constrained by contractors ability to vibrate and “strike off” the surface, generally with a vibrating beam or screed as well as the joint layout considerations. Formwork are used on all free edge and set and checked to desired finished floor levels (FFL). All edge interface must have adequate dowels to ensure load transfer and movement where required. As areas are small, strips are generally finished with walk behind trowels.

Pros:

  • high control of surface flatness and levelness
  • less investment in equipment systems

Cons:

  • Labour intensive
  • More joints in the floor
  • Reduced productivity ~500-600m2/day
  • more expensive $/m2

Laser Screed “Large Bay” Placement:

Large bay placement involves casting a monolithic slab in a single pour sequence by way of a laser controlled mechanical screed (laser screed).  In this system a “bay” is designed as per optimal movement joint layout, generally 30-40m x 30-40m. Leave in place steel movement joints are placed to isolate the bay perimeter acting as both concrete shutters and joint edge armouring after finishing and joint opening. As the the laser screeds strike off and vibrate concrete to laser controlled levels, there is no requirement for internal “bay” formwork or spot levels.  As areas are larger finishing is accomplished by ride on trowels and walk behind trowels.

Pros:

  • Automated control of flatness and levelness
  • High productivity, screed ~400m2/hr
  • Less labour inputs, fatigue
  • decreased cost/m2 production
  • Strong marketing value in marketplace as “laser screed contractor”

Cons:

  • Higher initial investment
  • less control of finishing works as area is larger

 

Examples of relevant products

S-15R Laser Screed

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S-485

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Permaban Signature Joint

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