A commercial client approached Smartlift with a challenge- a foundation ground floor retail space was structurally sound but suffered cosmetic damage to the floor levels. The floor was high in places and low in others. The unevenness made it a point of concern due to possible tripping points. This was not satisfactory , as the client takes safety and well-being of their retailers and customers very serious. An upgrade repair was required.
The time-frame to complete this repair was extremely narrow. The work had to start Dec 7, 2018 and be finished by the end of Jan 2019, and with the Christmas period being one of their busiest periods, this left approximately 32 days to level 1600m2 of concrete foundation.
Major constraints and solutions
- Off the clock heavy-noise activity 12 am to 8 am. Shopping hours not to be disrupted
- Zero dust or contaminates to enter the constantly operating mall. Smartlift installed custom designed dust vacuum and filter equipment to create a negative airflow environment in the work-space to eliminate dust getting into the functioning shopping area. Smartlift had special concrete grinders and cutters fitted with dust extraction vacuum kits, with bags being replaced constantly and disposed of in special bins, then transported off site.
- Limited access to site and delivery trucks were not to be held up- the supply of materials and removal of hundreds of cubic metres of surplus fill from site.
- Constant need to open areas of site to allow for subcontractors. Smartlift designed an efficient 24 hour ‘day and night’ roster, using a 12-hour day shift and an 8-hour night shift to enable ‘rotating cordon’ WORK PLACE areas so the work-space could be shared with other contractors throughout our contract
- The ability to provide a large team of experienced staff at short notice to get the job completed on time, to budget, and with meticulous attention to labour health and safety requirements.
- Health and safety factors- shift workers, fatigue, machinery operating in a confined space, exhaust fumes, noise, dust management.
Description of area: 1600m2 of 200-280mm thick structural concrete floor slab with double reinforced steel, and numerous support piers and columns.
Smartlift designed a matrix of 437 x 300mm holes to be core drilled through the 200-280 mm thick concrete, holes to be excavated down 800 mm, concrete jacking pads to be poured and cured, screw jacks installed. An orchestra of staff working simultaneously and meticulously were able to lift the slab to the required Datum.
Once the lift was complete and to spec, (+/- 1.5mm over 3m ) lightweight aerated concrete was then pumped into the holes and under the floor to completely fill the cavities created by the lift- up to 40 mm in places.
This needed to cure and the DPC had to be reinstated, followed by reinstating the reinforced floor. The remaining cracks were then ground out and epoxy injected, then ground flush.
It was not just a simple matter of lifting a sagging concrete floor to level- there were some areas that were higher than the datum point and they had to be lowered. All low areas were identified, lowered by a variety of means including grinding (up to 10mm), scarifying (up to 20mm) and saw cutting and spade jack hammering (over 20mm) followed by installing a specialist screed system designed by Smart Lift Systems which was bought in to achieve the required design RL’s (Relative Levels).
The ingenious design of the Smartlift system is the jacks remain in place after being wrapped in a protective covering. This means should another major event cause more repairs to be done to the building, these jack points can be opened up and the same jacks reused to re-level the concrete slab again.
Within 5 weeks the floor had been levelled, void filled, core holes (jacking points) filled, heavy machinery removed and the final grind of high areas, epoxy injecting the cracks, and final floor levelling compound applied and sanded smooth to the required tolerances.
Health and safety report: NO incidents.
Delivered as promised, on time and on budget.