NEWS AND BLOG

Introduction

Tilt-up construction is a method for building concrete walls by casting the concrete panels horizontally on the ground, lifting them into place, and setting them on the foundations. Tilt-up construction is commonly used in warehouses, industrial buildings, and distribution centers. The process has gained traction due to its cost-effectiveness, lower lead time, and faster construction than traditional methods. At The Austin Company, we strive to deliver the best structural solutions for each project, so let’s dig deeper into this topic and discuss when tilt-up walls are most suited for your project. We’ll also discuss the design and construction process, safety measures, environmental considerations, and future trends in the tilt-up field.

Understanding Concrete Tilt-up Construction

History of tilt-up construction

Tilt-up construction has a surprisingly long history, dating back to the early 1900s in the United States. Robert Aiken, the “father of tilt-up,” started using this technique around 1905. It was widely used during the Great Depression for its cost-effectiveness and became a dominant method for factories and warehouses in the 1950s.

Tilt-up walls have several advantages over traditional construction methods. They can be faster, cheaper, and offer more design flexibility.

Comparison with Precast Concrete

Tilt-up walls are often used as an alternative to precast concrete walls. The most suitable choice usually depends on specific project needs. Tilt-up walls are ideal for projects prioritizing speed and design flexibility since they are faster to erect once the concrete panels are cured, especially for projects with larger panels. Precast panels can also be installed fast, but the lead time for factory production can affect the schedule. Because of this lead time, precast drawings are usually issued to the precast fabricator earlier than other design packages, thus reducing the flexibility to accommodate changes as the design and construction sequences progress. Tilt-up construction offers additional cost savings since there is no transportation cost for panels cast on-site. On the other hand, precast panels are better suited for projects requiring higher strength, consistent quality control, and tight site availability. Tilt-up panels require a large flat area for casting beds and are highly impacted by weather conditions during on-site curing. Whereas precast panels are fabricated in a controlled factory environment, ensuring consistent strength and quality. From our experience, due to weather considerations, precast panels are usually more favorable in the northern regions of the United States, while tilt-up panels are favorable in the South.

Comparison with Cast-in-Place Concrete

Traditional cast-in-place concrete walls are rarely used for your typical box-shaped structures. Cast-in-place is the process where concrete is mixed and poured directly into forms at the building site, with walls built vertically one section at a time. They are a good choice for complex shapes and sites with extremely limited space. They are usually more expensive since formwork can cost up to 50% of the concrete work cost and require more on-site labor. The process is also slower to allow curing between sections. It is, however, the most flexible option since walls can be formed into any shape needed for the design and offers a monolithic construction with no weak connections.

Key Components and Materials

In addition to concrete, steel reinforcement, and formwork, tilt-ups require embeds and lifting inserts that provide secure points for lifting the panels upright and into place using a crane. Sealants can be used to waterproof the joints. The panels are poured on a casting bed that is a flat and level surface (concrete slab or a compacted base) prepared on-site. Depending on the project, the slab-on-ground can sometimes be used as a casting bed.

Planning and Design Phase

Structural Engineering Considerations

If tilt-up panels are found to be the most effective option for your project, the design team proceeds with advancing the design. Structural engineers calculate the loads and steel reinforcement needed in the panels. The panel thickness is determined based on total height, loads, and fire resistance considerations. Engineers also consider the lifting points and stress the panel will experience during lifting and erection. Once the panels are designed, the engineers proceed to design the foundations and the connections between the panels and the foundation.

Architectural Considerations & Coordination with Stakeholders

Working closely with the engineers, the architects work to locate and design openings in the panels that can range from small window openings to large overhead and loading dock doors. The architects can also create a variety of finishes on the concrete surface using patterned molds (or form liners) and reveal that can add depth and shadow lines to the façade. Color pigments may be added to the concrete mix to achieve a desired concrete color, and if a concrete finish is not desired, cladding materials and veneers can also be used as an alternative. Once the design is complete, the drawings are shared with the owner and different stakeholders for their review. The general contractor and responsible subs can also review the design, considering the design feasibility and construction sequencing. The design is then revised and fine-tuned based on comments received and construction can proceed.

Construction Process

Site Layout and Construction

Proper site selection and preparation are also important for a successful tilt-up project. The site should be flat and large enough to accommodate the casting beds. The construction team starts by clearing the site of any vegetation and debris and grading it properly to achieve a level surface. A layer of crushed stone is added as a subbase, and 2-3” of unreinforced concrete is poured on top (mud slab) to form the casting bed. This is usually required to stabilize the soil and provide adequate capacity to support the weight of the casting bed and concrete panels above. The panels are built by laying out the steel reinforcement first, then pouring, finishing, and curing the concrete.

Panel Lifting and Erection

When the concrete reaches a certain strength, the panels are ready for lifting and erection. A crane is brought on-site and is used to lift the panels at the predesigned lifting insert points. The panels are carefully lifted and placed on a grout bed on top of the foundations. The connection is usually supported in place using steel angles or channels with field welds. Lifting inserts are then grouted solid and deadman anchors are installed to brace the panels until the roof is installed and the building is enclosed.

Safety Measures and Regulations

Given the complexity of concrete construction, proper safety measures must be followed before and throughout the construction. A safety plan and list of emergency procedures must be prepared. Proper training must be given to all workers involved in the process. Crane operations are critical yet potentially dangerous, so only qualified personnel should operate the cranes and follow a well-rehearsed lifting plan. A lifting plan considers weight limits, lifting points, and communication protocols. Workers on-site must always wear personal protective equipment (PPE) and abide by OSHA standards and regulations. These standards cover various aspects like fall protection, rigging, and safe use of cranes. State and local regulations regarding construction safety shall also be followed. To manage risks, a proper contingency plan should be put in place to address unfavorable weather conditions, poor material qualities, safety incidents, schedule, budget, etc. The plan should include mitigation strategies to address these risks and ensure that the construction can proceed on time and within budget.

Environmental Considerations

Even though concrete production is a significant source of greenhouse gas emissions, tilt-up construction can offer some environmental benefits compared to other methods. Since panels are cast on-site, the emissions due to transporting materials and prefabricated systems can be drastically reduced. The concrete mix and the casting bed can also include recycled materials such as crushed concrete. The amount of formwork needed for horizontal construction is also less than typical wall construction methods, and the formwork can be reused (metal) or recycled (lumber). Finally, concrete is great at absorbing and releasing heat slowly, which can help regulate indoor temperatures and reduce energy consumption for heating and cooling.

Future Trends and Innovations

While tilt-up is a well-established technique, innovations are still developing and improving the process. These can include material innovations such as self-compacting concrete, ultra-high-performance concrete that allows for thinner panels, and bio-based additives that reduce the environmental impact. Digital fabrication, BIM integration, and robotics can also improve coordination, efficiency, and safety. Tilt-up construction is becoming more versatile with techniques allowing for complex shaped and curved walls to be incorporated into the design.

Conclusion

In conclusion, tilt-up construction is a great solution for various commercial and industrial buildings. It can lead to a fast, inexpensive, and durable design that allows for flexibility for the construction team and the owner. Delivering cost-effective solutions to our clients—including projects with tilt-up panels—is a project deliverable for our team at Austin. We are always ready to offer consultation, so don’t hesitate to reach out and discuss your project needs with one of our in-house experts.

To learn more about Austin’s engineering capabilities visit Austin’s Design and Engineering page.

GEORGES ABDALLAH Structural Designer Call 440.544.2289 | Email Georges | View Profile