Fibre reinforcement in greenhouse construction and horticulture

Dutch greenhouse horticulture has some of the largest continuous concrete floors and paths in the country. From ebb-and-flood floors to loading and unloading pits: concrete plays a central role in greenhouse construction. Fibre reinforcement offers specific advantages here, mainly because of the chemical loading, the moist environment and the large, often jointless surfaces that characterise the sector. This article discusses the applications.

The specific environment of a greenhouse

Concrete in greenhouse horticulture faces a combination of loads that few other sectors encounter:

• Chemical exposure from fertilisers, crop protection products and nutrient solutions that can end up on the floor.

• Permanent moisture loading, from irrigation water, condensation against the glass and the high humidity inherent to a greenhouse climate.

• Intensive transport traffic, from hand-pushed trolleys to automated transport systems and robots travelling the same routes daily.

• Soil-related risks, such as subsidence from a falling water table or ground movement, which can lead to cracking and unevenness in floors and foundations.

Why fibre reinforcement fits well here

• No corrosion risk under chemical and moist exposure. Synthetic and basalt fibres are chemically inert and therefore unaffected by the action of fertilisers and crop protection products on reinforcement — a risk that does exist with traditional steel reinforcement once the concrete cover is damaged or insufficient in a permanently moist greenhouse floor.

• Suitable for large, continuous surfaces. Greenhouses often have floors and paths of thousands of square metres. Fibre reinforcement makes it possible to build larger areas with fewer shrinkage joints than with traditional reinforcement, which is relevant for an even, obstacle-free floor surface over which transport systems and trolleys must be able to travel.

• Faster to complete for large-scale projects. For projects involving thousands of square metres of concrete floor and path (as is common in greenhouse horticulture), eliminating a separate reinforcement step delivers a significant saving in labour hours and lead time.

• Resistant to intensive, repetitive transport traffic. Fibres distribute the load from repeated travelling transport (trolleys, transport systems) more evenly through the mix, which slows cracking on heavily used routes.

Specific applications in greenhouse construction

• Concrete floors and paths within the greenhouse: the main application by surface area, where fibre reinforcement contributes to a longer lifespan under intensive transport traffic.

• Ebb-and-flood floors: specific floor systems for flood-irrigating growing tables, where watertightness and chemical resistance to nutrient solutions are important requirements.

• Loading and unloading pits: heavily loaded, often moist zones where daily transport takes place.

• Foundations of the greenhouse structure: here the primary, calculated reinforcement usually remains necessary due to structural requirements (wind loading on the greenhouse structure, anchoring), but fibre reinforcement can play a supplementary role in crack control.

• Transport channels and paving around heat storage and CHP installations: where chemical resistance and watertightness are equally relevant.

Why this is relevant given the sector's challenges

Due to climate change and a falling water table, the foundations and paving of greenhouses increasingly need to withstand ground movement and subsidence. This increases the risk of cracking in existing and new floors and paths — precisely the problem that fibre reinforcement helps control by bridging crack planes and distributing loads more evenly.

Points of attention

For the primary, structural foundation of the greenhouse structure itself (where wind loading and anchoring of the upright structure are central), traditional, calculated reinforcement usually remains necessary — seek advice from your structural engineer for this. For floors, paths and non-primary structural elements, fibre reinforcement is often directly applicable, with the added benefit that large surfaces can be completed faster and with fewer labour hours.

In conclusion

The combination of chemical exposure, permanent moisture loading, intensive transport traffic and large, continuous surfaces makes greenhouse construction and horticulture a promising application for fibre-reinforced concrete — particularly with synthetic or basalt fibre because of the absence of corrosion risk.