Revealing the Ubot Flat Slab Construction Process

Ubot flat slab construction is a crucial step in the installation and construction process of flat slabs without beams. However, not every construction contractor has the expertise required to construct flat slabs in accordance with the proper standards and specifications. With 10 years of experience in applying beamless slab solutions, LPC engineers have developed a construction process based on flat slab design standards that is suitable for the domestic construction market. Let’s explore it with LPC.

Ubot Flat Slab Solution

The Ubot flat slab solution is a two-way monolithic lightweight slab system that uses Ubot plastic void formers to create voids within the slab. These void formers are arranged parallel to one another, forming an interconnected system of concealed I-shaped beams in two perpendicular directions.

Ubot Flat Slab Construction Steps

Step 1: Install the slab formwork

Step 2: Install the lower slab reinforcement and evenly distributed lower reinforcement

Step 3: Install the Ubot void formers

Step 4: Reinforcement installation steps before pouring concrete for the Ubot slab

Install lower reinforcement for the slab voids (if any)
Install the upper slab reinforcement and shear reinforcement
Install column-cap reinforcement
Install U-shaped edge reinforcement
Install upper reinforcement
Install punching shear reinforcement
Install C-shaped reinforcement to stabilize the slab

Preparatory Work Before Ubot Flat Slab Construction

Recheck the beamless slab structural drawings: void former spacing and positioning
Mark the column-cap positions (using chalk lines, marking lines, etc.)
Mark the position for the first row of void formers in both directions by stretching string lines or snapping chalk lines

Step 1: Install the formwork for the reinforced concrete flat slab

Similar to conventional slabs, Ubot beamless flat slab construction uses a wedge scaffolding system or PAL scaffolding, steel box-section joists measuring 50 × 100 mm and 50 × 50 mm, and a wooden slab formwork system that ensures sufficient strength and tightness.

Ubot flat slab formwork installation — **Step 1: Install the slab formwork**

Step 2: Install the lower slab reinforcement and evenly distributed lower reinforcement

*Step 2: Install the reinforcement and slab reinforcement*

Step 3: Install the Ubot Void Formers

Attach the cover panels to the Ubot void formers. The cover panels prevent concrete from flowing into the void formers and allow for more effective vibration, ensuring the density and compactness of the concrete. In addition, the cover panels allow site supervision engineers to inspect the concrete during concrete placement when constructing the beamless flat slab.

Place the void formers according to the design drawings. Position the first void former. Install the void formers at the designed spacing and connect them using rigid connecting bars.

Install the first row of void formers using the stretched string line (chalk line) as the reference. Next, the void formers are installed progressively and automatically aligned by the connecting bars

Step 4: Install the upper slab reinforcement and shear reinforcement

Note: During installation of the upper reinforcement layer, when heavy materials need to be moved across the surface of the void formers, workers should step on the base positions (corners) of the void formers or use planks where necessary. This is recommended as the safest position for moving across the surface of the void formers; movement through the center of the void formers should be minimized during flat slab construction.

When installing the upper slab reinforcement, install the shear reinforcement at the interface between the column cap and the void slab at the same time to avoid overlapping work during construction.

Step 5: Install the column-cap reinforcement

Column-cap reinforcement is installed in the column-cap areas specified in the design.

Step 6: Install the U-shaped edge reinforcement

At the slab edges, for slabs without edge beams, install the U-shaped edge reinforcement system.

Note: During installation of the upper reinforcement layer, when heavy materials need to be moved across the surface of the void formers, workers should step on the base positions (corners) of the void formers or use planks where necessary

Step 7: Install the upper reinforcement

The upper reinforcement is installed together with the evenly distributed upper slab reinforcement.

Step 8: Install the punching shear reinforcement

Punching shear reinforcement is arranged around the column-cap area according to the design.

If the punching shear reinforcement does not align with the slab or column-cap reinforcement bars, additional structural reinforcement bars must be installed to keep the punching shear reinforcement in a vertical position.

Step 9: Install C-shaped reinforcement to stabilize the slab

The purpose is to tie the upper and lower reinforcement layers together into a single system, limiting the upward displacement of the void formers during concrete placement. Density: 4 pieces/m²