In 2017 Monkey Island Estate, owned by Wessex Water was looking to invest in the property and bring it back to sustainable use. Plans were submitted to demolish the existing outbuildings, renovate the Pavilion and Temple buildings and create a new building for staff accommodation, an energy centre, and a bin store.
The complete refurbishment means loads are increasing considerably on foundations which therefore needed ground improvement. Temple Building – Approx. 108 linear metres stabilised to depths 2.7m to 4.7m bgl; Re-level 135m2 floor slab that has dropped. Pavilion Building – 9.5m walling to 2.2m depth, 3 columns to 3.2m depth; Stabilise 165m2 of floor slab.
Geobear was contacted by Wessex Water in order to provide a proposal for the geopolymer injection treatment works to approximately 297m2 of floor slabs over two buildings, comprising of 162m 2 in the Pavilion Building and 134.8m 2 in the Temple Building, whilst also providing reinforcement to soils underlying specified foundations at the Monkey Island Hotel to facilitate the proposed refurbishment works.
The requirement for the ground improvement works was due to the fact that the underlying soils in-situ did not contain satisfactory strength to enable the proposed refurbishment to take place. Therefore the soils underlying the specified foundations were required to exhibit suitable strength in order to safely enable the refurbishment works to take place.
Our works were separated into three phases: Slab Stabilisation, Slab Re-levelling & Ground Improvement.
We delivered a series of geopolymer injections in order to stabilise the 162m2 area of floor slabs within the ‘Pavilion Building ’. The requirement for our work was due to the presence of incompetent soils underlying the area of slabs in question.
In order to achieve shallow reinforcement, the selected geopolymer was injected through each slab to fully re-establish contact between the underside of the slab and the underlying soils by filling any voiding/permeating any voided soils directly beneath the slab. This ensures the presence of a firm horizon of reinforced soil to act as a sub-base for the slabs to sit on.
Once injected, the geopolymer moves both horizontally and vertically in its liquid state to a region that allows the material to take the path of least resistance, and thus lies beneath the region of the slab with the greatest need to be stabilised (as regions of the slab that do not require stabilisation will be sitting on competent strata). Once this had taken place, the geopolymer polymerised, which resulted in expansion, and in turn, an upwards pressure being placed upon the underside of the slab.
The main aim of this phase of geopolymer injection works was to re-level 134.8m2 of floor slabs within the ‘Temple Building ’. The floor slabs had dropped by approximately 25mm from the original level due to compaction and consolidation of the underlying soils.
The chosen geopolymer was injected into the shallow area directly beneath the slab and fully re-established contact between the underside of the slab and the underlying material by filling any voiding. The upwards movement was monitored by laser and continued until the desired amount of lift was been achieved.
Following discussions with representatives from Wessex Water, it was agreed that Ground Improvement works would provide the treated stratum underlying the specified sections of walling within the Temple & Pavilion buildings to exhibit the strength required to safely transfer the loadings.
Ground Improvement relates to soils being treated at a greater depth and thus most concerned with the forces provoked by loading. The objective of this treatment was to compact the underlying soils via elimination of voids by filling and compacting /consolidating, the expulsion of air and water and agglomeration of the soil
Once injected, the geopolymer migrated and expanded both horizontally and vertically to a region that allowed the material to take the path of least resistance, and thus has the greatest need to be reinforced. Once this had taken place, the geopolymer expanded and placed pressure on the region of soil surrounding the injected material (and ultimately the foundation in question).
The success of the project was verified through the capture of laser monitoring data for the slab and re-levelling, and post dynamic cone penetrometer testing to validate the ground improvement.
The project was time-sensitive as the owners wanted the hotel to be open for the late Autumn and festive. As the only viable access was via the 12-tonne weight limit pontoon, major underpinning plant was not a viable solution and would not have had the flexibility to work in and around other contractors.
Wessex Water, therefore, needed an alternative and innovative solution and Geobear with its pioneering Geopolymer technology were asked to provide a proposal which was duly accepted.
The added value in Geobear’s offer came from:
- non-disruptive nature of Geobear’s solution, no requirement for excavation or heavy machinery
- less time to implement vs. other remediation methods
- proven to work, with over 200,000 projects worldwide
- long-lasting, not quick fixes
- over 30 years of expertise in ground engineering
- working around other contractors’ requirements on site
- easy to work with, Geobear’s people are friendly and approachable