Pouring concrete footings is going through a phase change. While concrete pouring has involved using rigid wooden forms until it can be cured for years, newer ways are cropping up that aim to improve efficiency and the environmental impact of the process.
A prime opportunity for this approach lies in off-form concrete, which is concrete cast without any frame or mould.
Off-Form Concrete: A Sustainable Choice
Off-form concrete involves pouring concrete into excavations or directly onto the ground surface without conventional timber-board forms. Material costs are reduced, and environmental impact is lowered.
At the same time, there is minimal wastage. This method is particularly suited to projects where the outer finish of the concrete is not a priority or where it will be covered up.
Techniques for Pouring Concrete Footings Without Forms
Trench Footing Method
One method is to trench-foot it, dig a trench in the ground in the shape you want your footing to be, pour your concrete directly into the trench and let it cure. This method can be used where the soil is stable enough to hold its shape until you pour in the concrete.
Controlled Low-Strength Material (CLSM)
Another interesting invention is the use of Controlled Low-Strength Material (CLSM), also termed flowable fill. CLSM refers to the self-compacting, cementitious material that replaces compacted fill or conventional concrete. CLSM flows into the placed condition without the need for vibration or tamping for compaction.
Use of Geotextiles
Other applications encompass the use of geotextiles as an alternative to formwork. When installed in the excavation, geotextiles provide permeable fabrics to contain the concrete during placement and transmit water simultaneously. When used in wet conditions, these materials save labour and precious time.
Slip Forming
Slip form is a technique for pumping concrete into a form that moves continuously when it is time to cast the next round. Still, it can be varied to allow for footings so that the form is also moving (no formwork is required, and it can proceed continually).
Biodegradable Formwork
Innovations in biodegradable materials mean that future formwork could be both temporary and degradable, leaving behind no waste or virtually none, as in research being conducted at Leeds University in the UK, where foam grows and hardens to create a mould that degrades after the concrete has cured.
These properties make temporary formwork an attractive option for sustainable construction in sensitive environments.
Advantages of Formless Footing Techniques
Reduced Material Costs: Eliminating wooden forms saves on material costs.
Environmental Benefits: Less waste and reduced impact on the environment.
Time-saving: Reduced construction time because there’s no need for form-creating and stripping
Cost-effectiveness: Reduced construction costs because of less time spent on construction
Water-saving: Reduction in the use of water for concrete casting
Versatility: Ability to pour footings in difficult or remote locations.
The Critical Role of Concrete Footings in Construction
Any building project begins with concrete footings. These footings serve as support rooms to lay a base for the general structure of a building so that the weight of the building can be spread out evenly without settling and structural damage.
When concrete footings are poured, it is a process that one must pay careful attention to avoid early cracking or failure.
Why Perfect Footings Are Essential
Stability and Support
A footing’s principal function is to provide a solid base for the building above. The footing must be able to take the load of the building plus the secondary stresses of earthquakes or high winds. A footing poured with precision ensures that the structure will not move or crack under stress.
Load Distribution
A well-designed footing spreads the load of the building over a larger area, and this helps to prevent the building from sinking or leaning into the ground. In areas with problematic soil, off-form concrete footings can be shaped to match the specific load distribution of the project.
Soil Interaction
Finally, the interaction of the footing with the soil (colour illustrations above, right) is of utmost importance. The footing must be poured deep enough (so it only stops on stable soil) and sufficiently wide (proportional to soil strength) so that the different parts of the building don’t settle differentially. Differential settling leads to cracks and eventual failure (colour illustrations below).
Moisture Control
Moisture is also controlled by concrete footings. These support the structure without allowing water to wick from the ground into the wood materials or brick wall.
Ensuring Perfection in Footing Construction
Achieving perfection in pouring concrete footings involves several key steps:
Site Preparation: The site needs to be prepared, with the ground levelled and stabilised by a lack of soil erosion. All matter or organic material must be removed from the site, and the soil must be compacted.
Design and Planning: You have to figure out what size your footing needs to be in order to support the building – size, shape and load requirements are all things you need to factor in.
Material Quality: High-quality concrete. Ensure you use a strong mix design that will last indefinitely without cracking and/or corroding.
Poured: The concrete needs to be poured slowly and evenly to avoid creating void spaces or weak spots. For off-form concrete, this means thinking carefully about the mix to encourage it to flow evenly and set properly.
Curing: Concrete must be allowed to cure slowly after pouring to maximise its strength. That requires it to be kept moist and out of extreme temperatures.
Conclusion
Pouring concrete footings correctly is critical in the construction industry. If the footings fail, they fail the rest of the project as far as any thoughtful contractor is concerned. A botched job means thousands of dollars worth of repairs. So, it behoves any construction professional to know what a footing is, why it matters, and how it matters what off-form concrete gets poured into it. Poured footings may be invisible, but more is needed to ensure the longevity and stability of a building as much as getting the footings just right.
If you want your concrete footings poured correctly then contact the experienced team at LFCS.
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