Sonotubes®: Types, Uses and Benefits

Chapter One – What is a Sonotube®?

A Sonotube® is a cylindrical form made of layered cardboard, typically treated with a wax coating or laminate. These tubes are designed for pouring concrete to form structural supports such as columns and posts. The Sonotube® brand is a trademark of SPC RESOURCES, INC. These forms come in various materials including fiber, plastic, and composites, catering to diverse uses from home improvement projects to major construction endeavors. Their sizes range widely, from small versions available at hardware stores to large tubes several feet in length with diameters measured in feet.

To use a Sonotube® for creating a column or support, it is placed in the desired position and secured. Concrete is then poured into the tube and allowed to set. After the concrete has fully cured, the tube is removed, leaving behind a robust and durable column or support.

Sonotubes® are available in various sizes to suit different needs, and the choice of size depends on factors such as the structure's design, building regulations, and the type of supporting soil. While standard Sonotubes® can endure exposure to water for up to 24 hours, custom versions are designed to withstand moisture for up to 72 hours.

Chapter Two – What are the standard sizes of Sonotubes® available?

To create columns and supports with precise dimensions, concrete forms need to have perfectly smooth interiors and be able to endure the pressure from poured concrete while maintaining their shape. Traditionally, constructing these supports involved building wooden or steel molds, which were time-consuming to assemble and disassemble. This method not only delayed construction but also resulted in columns with uneven and rough surfaces.

The advent of Sonotube® forms has revolutionized the process by eliminating the need for labor-intensive and time-consuming mold construction. Sonotubes® simplify the creation of columns and supports, providing a smoother finish that is both cost-effective and structurally reliable.

The durability of Sonotubes® comes from their tightly wound fibers, which are bonded with adhesive to ensure a smooth, consistent surface. This is achieved by wrapping strips of heavy paper around a mandrel and sealing them with a pressure roller.

Forms of Sonotubes®

The introduction of Sonotubes® transformed the approach for architects, contractors, and designers by offering a flexible and adaptable solution for placing columns without the need to fit traditional molds or forms. These tubes present a practical alternative for forming columns, streamlining the process to be quicker, simpler, and more efficient.

Sonotubes® come in a variety of sizes, making them versatile for numerous applications. They are commonly used to form columns for buildings, patios, cabanas, and other structures. Despite being constructed from tightly wound paper, Sonotubes® are robust enough to support several cubic yards of concrete, which, combined with their cost-effectiveness, makes them a preferred option for structural support construction.

The chart below outlines the available dimensions of Sonotubes® and the corresponding cubic yards of concrete required for different column heights.

While manufacturers offer Sonotubes® in various standard sizes, many also provide custom designs to meet specific customer needs.

All types of Sonotubes® are engineered for use in commercial construction. The wide range of sizes available helps enhance the efficiency of construction projects by providing versatile options for different structural needs.

Finish Free

Finish-free Sonotubes® are designed for applications where a flawless column surface is essential, free from spiral marks, seams, air bubbles, voids, or other imperfections. These tubes feature an interior coating that ensures an exceptionally smooth finish. Additionally, they come with a strip cord that facilitates the quick removal of the form. However, finish-free Sonotubes® are available in a limited range of diameters, from 12 inches to 36 inches, and can accommodate concrete volumes ranging from 0.349 cubic yards to 3.142 cubic yards.

Commercial Sonotubes®

The production of commercial Sonotubes® involves using materials designed to meet the rigorous demands of commercial construction. The process starts with water-resistant paper that can endure up to 72 hours of rainfall. These tubes are crafted from tear-resistant materials with exceptional strength, capable of withstanding pressures of up to 20 feet.

The high durability of commercial Sonotubes® is attributed to their poly-woven exterior, which is specifically engineered for commercial-grade use. These Sonotubes® are offered in a wide range of diameters, from 6 inches to 60 inches, and are available in lengths ranging from 12 to 20 feet.

Blasting Tubes

In the mining industry, blasting Sonotubes® are used in blast holes to preserve their structure and prevent collapse. These robust and durable tubes are constructed from specialized paperboard that forms a watertight seal, ensuring exceptional water resistance and longevity during the blasting process.

Blasting involves drilling holes into rock faces, which are then packed with explosives and detonated to fracture the rock for additional drilling. It is crucial for the holes to maintain their dimensions to ensure the effectiveness of the subsequent drilling operations.

DIY Builder’s Sonotubes®

DIY Sonotubes® offer the same durability and strength as their commercial counterparts but are available in smaller diameters. They are ideal for projects such as building decks, setting fence and lamp posts, installing swing sets, and mounting mailbox posts. These DIY Sonotubes® come in sizes ranging from 6 inches to 12 inches in diameter and can be easily found at most hardware stores. They are typically available in standard lengths up to four feet.

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Chapter Three – How Sonotubes® Are Made?

The production of Sonotubes® follows a similar process to that used for creating tubing for other purposes. However, Sonotubes® are specifically designed with enhanced strength and durability to handle the pressures exerted by poured concrete. This necessitates the use of specialized materials and construction techniques.

Another distinguishing factor in the manufacturing of Sonotubes® is the scale of the equipment used. Since Sonotubes® can have diameters of up to 60 inches, larger mandrels are required for winding the paper strips to accommodate these substantial sizes.

Making Sonotubes®

Trimming Process

The initial stage in manufacturing Sonotubes® involves cutting cardboard sheets into strips. These sheets are drawn from a large roll of cardboard and fed into a cutting machine that slices them into ribbons of the correct width for winding onto a mandrel. As the sheets are processed, the resulting ribbons are collected on a reel.

Winding Process

The ribbons, which have been wound onto a heavy metal reel, are then transferred to the winding machine. Multiple ribbons are positioned side by side to be wound onto a mandrel—a cylindrical tool with an outer diameter that matches the inner diameter (ID) of the Sonotubes®. The winding is performed in a helical pattern, with the ribbons applied at an angle less than 90 degrees relative to the mandrel. This helical winding enhances the strength and durability of the Sonotubes®.

During the winding process, several layers of cardboard ribbons are applied, which determine both the thickness and the outside diameter (OD) of the Sonotube®. To achieve the required strength and durability, the Sonotubes® are wound multiple times to ensure they meet the specified thickness and performance standards.

Foam Adhesive

As the ribbons are wound around the mandrel, a heavy-duty foam adhesive is applied to ensure the ribbons are securely bonded together, preventing the formation of air pockets, bubbles, or voids that could compromise the smoothness and strength of the Sonotube®. The image below illustrates a simplified depiction of the adhesive application process as the paper ribbons are wound.

Sonotubes® are treated with specially formulated coatings and adhesives that impart water resistance, tear resistance, and exceptional strength. These properties are essential for withstanding the pressure exerted by poured concrete and meeting the required durability standards.

Pressure Roller

A critical aspect of manufacturing Sonotubes® is ensuring that the cardboard ribbons are securely bonded. The adhesive applied during the winding process holds the ribbons in place, preventing any movement or shifting. Additionally, a pressure roller is used to firmly press the ribbon layers. This roller helps to eliminate any voids, air pockets, or bubbles, ensuring a smooth and uniform final product. The pressure from the roller flattens the ribbons and evenly distributes the adhesive, enhancing the overall quality and durability of the Sonotube®.

Chapter Four – How Sonotubes® Are Used?

Sonotubes® offer a convenient and efficient solution for various construction tasks. Their robust and durable material, combined with their lightweight nature, makes them easy to handle and install. To achieve successful project outcomes, it is essential to follow a series of well-planned steps when using Sonotubes®.

Sonotubes® are favored for their impressive strength relative to their construction material. Traditionally, forming columns involved substantial labor to create the molds for concrete pouring, which was time-consuming and required significant planning and effort. The traditional method also limited the number of columns that could be produced simultaneously due to the time and equipment needed for molding and shaping.

In contrast, Sonotubes® are designed for single-use and do not need external support to stay in place. This allows for multiple columns to be placed simultaneously, significantly reducing both construction costs and time. Additionally, Sonotubes® are made from recyclable, biodegradable paper, which can be repurposed to produce new Sonotubes®.

Using Sonotubes® is significantly more cost-effective compared to purchasing pre-fabricated concrete columns or other support structures. Companies can buy multiple Sonotubes® for a fraction of the cost of acquiring a set of pre-manufactured columns, which also incurs additional expenses for delivery and storage.

Using Sonotubes®

Installation Location

Typically, Sonotubes® are partially embedded in the ground and are supported by a footing form that stabilizes the column and prevents it from shifting. Footings are crucial when the supporting soil is problematic. As the concrete column will be partly buried, it's essential to ensure that the bottom of the hole is level. Additionally, the hole must be free of water, as moisture can disrupt the proper placement of the Sonotube®.

Footing Base

The base of the footing can be either round or square and is typically made from plastic. For the Sonotube® to fit correctly, the top of the footing should be trimmed to match the diameter of the Sonotube®. Larger Sonotubes® may require more substantial footings, which should be solid and robust. The footing should fit tightly around the Sonotube® to prevent any movement when the tube is filled with concrete.

It is crucial to ensure that the Sonotube® is level upon placement and verify that it is properly plumbed.

Alternatively, footings can be constructed from concrete and shaped within the hole using wood forms and rebar. These footings can either be premade and inserted into the hole with rebar or constructed on-site with concrete poured into the forms.

Dirt Fill

Before pouring concrete, the area around the footing and base of the Sonotube® should be backfilled with soil, taking care not to dislodge the Sonotube® or affect its plumb alignment. Properly compacting the soil around the tube will enhance its stability and facilitate a smoother and more efficient concrete application.

Pouring Concrete

Various types of concrete can be used with Sonotubes®, depending on factors such as your location, the type of column being constructed, and the load the columns will bear. It’s important to distinguish between concrete and cement, as cement is just one component of concrete.

Concrete was developed in the 1980s as an improvement over traditional cement by incorporating ingredients that reduce the amount of water remaining after hydration. This mix decreases the size of water-filled pores, thereby enhancing the material's strength.

For added stability, it may be necessary to incorporate rebar into the Sonotube® based on the type of structure being supported. Rebar reinforces the concrete mix and should be positioned during the pouring process so that the concrete can adequately embed it.

Concrete typically consists of 60% to 75% sand, gravel, and rock, 15% to 20% cement, and 15% to 20% water by volume. The water chemically reacts with the cement to form a binding agent that solidifies the concrete into a strong, cohesive material.

Concrete Curing

The curing time for concrete depends on its composition and the weather conditions. While full curing typically takes about a month, concrete can often be used much sooner. The usual curing process follows this general pattern:

• 24 to 48 hours – initial set is complete, and forms can be removed. In the case of Sonotubes®, they can be cut away.
• 7 days – partial curing is complete
• 30 days - concrete should be fully cured

These times are approximate and can vary based on site conditions and environmental factors. A proper curing process is crucial for enhancing the concrete's strength, durability, water resistance, and wear resistance. The strength of concrete relies on the formation of crystals within its matrix, which develop through the chemical reaction between cement and water.

Chapter Five – What are the main benefits of using Sonotubes®?

Sonotubes® offer an eco-friendly, cost-effective, and efficient solution for creating cylindrical column structures. They are particularly well-suited for forming underground footings, helping to lower labor costs. The design of Sonotubes® allows for easy cutting and removal, eliminating the need for additional machinery or equipment.

Sonotube® Benefits

Rounded Shape

The rounded design of Sonotubes® ensures they fit seamlessly into various structures. Without sharp edges that might chip or crack, they feature smooth surfaces that blend well with the overall design of a construction project.

Economical Benefits

Sonotube® forms are more cost-effective compared to metal or fiberglass alternatives, allowing you to buy several Sonotubes® for the price of a single fiberglass form. Their availability in various sizes means you can purchase all the sizes needed for a project in one go.

Lightweight Advantage

One of the key advantages of Sonotubes® is their lightweight nature, which simplifies handling and reduces labor costs. Their ease of transport, maneuverability, placement, and storage makes them less cumbersome compared to heavier alternatives. Additionally, after use, the cardboard material of Sonotubes® can be repurposed, recycled, or reused, contributing to their environmental sustainability.

Easy to Install

One of the most noticeable advantages of Sonotubes® is their ease of installation. They don’t require complex construction or heavy equipment, as they can be handled and positioned by hand. Once in place with appropriate supports, concrete can be poured quickly and easily.

Speeds Production

Sonotubes® are perfect for projects involving multiple columns. Rather than waiting for each column to set before starting the next, you can place several columns simultaneously, significantly reducing the overall construction time. This allows for the pouring of all columns in one go.

Conclusion

• A Sonotube® is a cardboard concrete forming tube made of waxed paper or lamination that is wound into a tube into which concrete is poured to create supports, columns, and supports for posts.
• To create a column or support, Sonotubes® are positioned properly and securely. Concrete is poured into them and left to set. Once the concrete has cured and set, the tube is cut away, leaving a durable strong support or column.
• The introduction of Sonotubes® forms has removed the labor intensive time consuming methods for creating molds, forms, and castings for making columns and radically simplified the process.
• The manufacture of Sonotubes® is similar to the processes used to make tubing for other applications. The main difference between the methods is the strength, durability, and unique construction of Sonotubes®, which requires materials capable of withstanding the stresses produced by poured concrete.
• Sonotubes® are the most eco-friendly, economical, efficient, and effective solution for forming cylindrical column structures. They are an ideal method for forming underground footings to reduce labor costs.

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