SHOTCRETE CIVILS – STRUCTURAL SHOTCRETE
Substantially less formwork is required;
The formwork that is required is substantially lighter in weight;
Greater areas (m2) per day can be delivered consistently;
Project schedules are accelerated because of productivity and efficiency gains;
Faster project completion translates into substantial cost savings;
The inherent flexibility of shotcrete versus form & pour reduces the complexity of many structural forming challenges; and
More surface finishing options are available.
All vertical, two-sided formwork is designed to withstand a minimum of 2900 kg/m2 of concrete head pressure. The resulting forms are substantial and heavy to carry this high internal pressure.
With shotcrete applications, however, a one-sided form is all that is required and this form only needs to withstand 240 kg/m2 of pressure. This reduced pressure requirement is a direct result of the high velocity, pneumatic application of the concrete impacting over a small area as opposed to pouring in a form that has fluid pressure along the entire form length. There’s far less pressure at the bottom of a one-sided shotcrete form and the pressure resistance requirement is only to keep the form from moving or vibrating during the shotcrete placement.
With the dramatic decrease in form pressure, forms can be much lighter and thinner than traditional form-and-pour panels. And with the need for only a one-sided form rather than a two-sided form factored in, overall formwork materials can be reduced by up to 75%. In addition, the reduction in form pressure means that details for corners, intersections, fillers, and bulkheads are easier to produce resulting in significant material and labour savings.
The decreased volume of formwork materials required on the jobsite further reduces storage needs and crane requirements. The number of forms that must be stored offsite and transported to and from the jobsite is lessened; that also reduces costs while accelerating scheduling. By reducing the amount of formwork required and thus eliminating a substantial portion of transport requirements, a shotcrete application reduces the environmental impact of a project and contributes to more sustainable construction.
LABOUR AND SCHEDULE SAVINGS
When the quantity, size, weight, and complexity of onsite formwork are reduced, labour requirements are also minimized. When labour requirements decrease, schedules accelerate. Schedule acceleration reduces site overhead, which results in less consumption and greater sustainability. From the offsite prefabrication and delivery stage right through to clean-up at the end of the project, structural shotcrete can increase sustainability and result in a more durable, longer life structure that requires less maintenance in the future. As an additional bonus, fewer deliveries means less traffic congestion. On remote sites, the reduction in transport time and lessened crane requirements also reduces project completion timing and transport costs.
SHOTCRETE ADVANTAGES IN SPECIALTY APPLICATIONS
Shooting or finishing a wall from both sides with sacrificial formwork or insulation in the middle;
Laminating over an existing structure that is tight to the floor and ceiling with no access from above to pour concrete into traditional two-sided forms;
Creating curved walls without the cost of building complicated two-sided curved formwork;
Easily creating tapered concrete sections that provide the exact concrete thickness where needed;
Creating shotcrete wall finishes similar to architectural floor finishes with colour, stamping, carving, and offset facing not possible with traditional form liners; and
Hoisting or formwork moving challenges encountered in constricted spaces such as subways and tunnels are mitigated or eliminated when the form panel size and weight is reduced, or rendered unnecessary.
ENVIRONMENTAL IMPACT— SUSTAINABILITY
Wet-mix shotcrete placement creates a fresh concrete surface that can be a trowelled to a smoothly finished surface free of lift lines, and form tie holes. The surface is denser and can be treated like an industrial floor. The result is a longer life cycle with added protection against freezing and thawing, chloride penetration, abrasion, and wear from environmental conditions. These characteristics enhance the overall sustainability of the shotcrete application methodology. Structures that last longer have less overall impact on the environment.