Deep injection | URETEK

Lifting and levelling of aerodrome surface covers

The covering of taxiways and take-off and landing runways on aerodromes may sink

When using classical methods, restoring damaged sections along with strengthening the subsoil and replacing cover plates takes several weeks or even months, during which aerodrome cannot operate at full capacity. When using URETEK materials, restoration works take only a few days or even just a few hours.

Subsidence of aerodrome concrete slabs is a common problem in many airports across the world. Aerodrome surface slabs may be subject to subsidence due to increased volume of passengers and cargo, deteriorated drainage system, natural wear and tear of materials, etc.

Subsidence of concrete slabs within permitted limits is not dangerous and does not cause accident-prone situations. But if the weakening of soil under the aerodrome and subsidence of certain runway sections exceeds permitted limits, immediate intervention is required. Even if the condition of aerodrome cover slabs is not yet unsafe, it may lead to danger situation in case of sudden change in weather conditions. For instance, if water in the recesses of aerodrome surface freezes, it may cause planes to slide.

Strengthening of the soil under airfield

In order to restore concrete slab surface of aerodrome, it is necessary to strengthen the soil under the slabs. Traditionally, stabilisation and levelling of aerodrome surface slabs requires partial or complete dismantling, closing unsafe section for major repairs and involving heavy duty vehicles. After dismantling of the slabs, soil strengthening procedures are performed, followed by restoration of aerodrome surface.

When using modern URETEK technology and materials, it is not necessary to dismantle or replace the aerodrome surface in order to strengthen the soil under aerodrome and stabilise and level the position of concrete slabs, neither is it necessary to deploy heavy machinery.

For strengthening the soil, a certain number of holes with 16 mm diameter are drilled in aerodrome surface used for inserting geopolymer material to required depth.

Principle of the technology

URETEK material contains special geopolymer resins, which expand and harden when inserted in soil, achieving great strength in merely 15 minutes. That way, the soil under the airfield is strengthened, whereas restored section can be used almost immediately after performing the injections.

Technology allows restoring the site with only minor changes in flight plan that do not interfere normal functioning of the aerodrome. It is sufficient to plan repair works for the period when there are not many take-offs and landings. Due to the dimensions of equipment required for URETEK geopolymers injection and autonomous nature of transport equipment, it does not limit the aerodrome resources during restoration works.

Variations in technology

URETEK technology can be used in two ways to lift and stabilise airfield cover plates. Methods differ from each other in terms of the depth of geopolymers injection. Deep Injection method is used to restore former soil properties at the depth of several meters. For immediate stabilisation and levelling of concrete slabs, geopolymer material is inserted in the gap between soil and slab by using Slab Lifting method. In both cases, the position of aerodrome surface and concrete slabs is adjusted by means of laser levels with precision of ±1 mm.


Stopping subsidence of concrete pools and elimination of cracks

Water level may drop in concrete pools. In hot summer, it is sometimes explained by natural vaporisation. But it may also result from occurrence of cracks in pool structure due to foundation subsidence.

Problem can be solved by using geopolymers injection.

Unlike other structures, pool structure does not prescribe even minimum subsidence of concrete frame. If the pool subsidence has occurred due to insufficient compaction of soil or excess humidity of the soil under the structure, cracking of concrete is inevitable. As a result of cracking, water starts to leak gradually. This, in turn further aggravates the condition of soil around the pool. It may become unsafe and the site cannot be used any more.

When repairing a pool, just patching the cracks is not enough. It does not remove the initial cause of damage. If the cracks occurred due to weakening of soil under the structure and subsidence of pool frame, it is necessary to address the problems with soil and foundation first.

In that case, soil is strengthened before eliminating cracks, foundation lifted and stabilised if necessary. It is worth noting that when using modern URETEK geopolymers injection methods, the work cycle lasts only a day or two and it does not require earthworks or concrete works.

Deep injection

Cracks in concrete pools can be eliminated by using Deep Injection method, which allows filling cavities and voids in the soil under the pool with special geopolymer resins. After reaching the soil, geopolymers expand and harden quickly, exerting vertical pressure. That way it is possible to strengthen weakened and excessively humid soil under the structure.

Furthermore, geopolymers can be used to stop pool subsidence and stabilise its position, or even lift it to its former height where necessary. Due to their structure, geopolymers do not react with water, but force it into surrounding soil. Therefore, geopolymer resins not only strengthen the soil, but also function as waterproofing material.

Cracks in concrete can be patched only after strengthening soil and stabilisation of foundation.

Works algorithm

Geopolymer resins are injected through special holes (diameter of 12–16 mm), drilled in concrete or soil around pool’s perimeter. Holes are quickly closed after completing the injection.

URETEK geopolymer resins are not destructive. They are suitable for strengthening soil, lifting and levelling concrete structures. Everything related to altering the position of concrete frame is monitored in real time by using laser level (precision up to ±1 mm).

Due to their physical and chemical properties, geopolymers remain stable for a long time, including in humid environment. Material is chemically inert, ecologically safe and tested across the world during long term use.