Structural Shotcrete
In today’s increasingly competitive and challenging structural concrete marketplace, the need for innovative solutions to challenging forming issues is greater than ever. Shotcrete is a more logical and efficient option for structural concrete applications with the added benefits of sustainability and environmental responsibility
- 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.
LESS FORMWORK
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.
LABOR 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
With the combined savings achievable in materials, labour, and site logistics, structural shotcrete offers opportunities not available or associated with two-sided form-and-pour methodology:
- 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.
Concrete Repair & Rehabilitation
Concrete Repair & Stabilisation
One of the most economical and effective methods of concrete repair is by the shotcrete process. This is particularly true for repairs that would otherwise require forming, such as vertical and overhead repairs. Shotcrete materials are placed pneumatically onto prepared substrates, finished, and cured with no additional steps required. The use of bonding agents is not required or advised because consolidation and bonding of the material occurs during proper shotcrete application. As with all repair techniques, proper surface preparation is paramount in attaining a permanent repair solution. The shotcrete process is typically used to restore structural integrity, increase concrete cover over reinforcement, or both. It’s typically used when forming requirements are difficult and/or prohibitively expensive.
The shotcrete process will bond to a properly prepared surface with about 65% of the tensile strength that concrete bonds to itself internally (2mpa vs 3mpa). This high strength bond (effectively a monolithic structure) is why the shotcrete will not de-laminate and is an excellent concrete repair method
The contract above required major structural concrete repairs that included:
- Recording of all spalled concrete
- Removal via pneumatic breakers to 30mm behind existing reinforcing
- Wire brush of all steel with grinders
- Coating of steel with rust inhibitor
- Replace steel to deteriorated for re-use
- Install lightweight shuttering
- Surface saturate the existing concrete
- Apply a silica fume enhanced dry shotcrete (gunnite) of our own design in conjunction with our material partners
- Screed surface & steel trowel to F1 concrete finish
- Apply curing compound
This superlative concrete repair has stopped degradation and renewed the building structurally. Extending the lifespan of the building by over 25 years.
Lateral Support & Embankment Stabilisation
Lateral Support & Embankment Stabilisation
We offer a full design & construct package utilising an in-situ ground reinforcing system of grouted anchors, steel fabric and a layer of shotcrete that ties everything together.
Where the embankment is inherently stable and only requires erosion protection, we utilise smaller dowels and a layer of fibre reinforced shotcrete.
Our full range of architectural finishes are available in both instances
Silo Relining, Repair, & Hopper Construction
Silo Relining & Repair
Silos can be given a new lease on life with a variety of shotcrete products ranging from a sacrificial 80mpa HSWR shotcrete liner for use in ore silos, new rebar and structural shotcrete to condemned silos that effectively create a new structure within/out.
We have our own platform access equipment allowing us to pass on cost savings to our clients.
For Silo repairs, we offer Carbon Fibre solutions along with shotcrete application.
The shotcrete process will bond to a properly prepared surface with about 65% of the tensile strength that concrete bonds to itself internally (2mpa vs 3mpa). This high strength bond (effectively a monolithic structure) is why the shotcrete will not de-laminate and is an excellent concrete repair method
Carbon fiber provides existing concrete structures with the strength and load tolerance necessary to repair and maintain the integrity of the structure. Unlike steel, carbon fiber technology is a longer lasting, more cost effective alternative for use on cold joints and other small areas
We can design and install a hopper for your silo, regardless of size or shape. The installation of a hopper allows for complete clean-out eliminating the need for human entry. Dangers of entering bins include: atmospheric hazards, combustible hazards, grain engulfment, entrapment, and asphyxiation. By increasing the slope of your existing hopper, you can eliminate cross-contamination of grains or products and avoid dangerous human entry for cleaning. The ease of adding a concrete hopper quickly maximizes the simplicity and efficiency of your daily operation.
Architectural, Skate-parks, & Swimming Pools
Architectural, Skate-parks, & Swimming Pools
Shotcrete is the material of choice for an increasing number of architectural applications. From intricately formed building structures like skateboard parks to landscapes, artificial rockscapes, zooscapes, aquariums and natural swimming pools.
Shotcrete Africa SCP are not pool builders, however due to our excellent and guaranteed quality we are preferred shotcrete applicators for Pool companies like Blue Lagoon pools who are responsible for the pools seen on our site.
Mining – Bulk Shotcrete
Mining – Bulk Shotcrete
Shotcrete Africa has the equipment and ability to place over 500m3 of shotcrete in a day. Unfortunately we don’t often find sites where that type of productivity is called for, but where we can offer large cost savings is in the mining/bulk shotcrete environment.
Boxcuts and large areas requiring shotcrete cannot be placed faster by any other company in Africa. Because we can place twice as much shotcrete in a day than other companies that provide shotcrete/gunnite, our cost per m3 is less.
We guarantee best quality shotcrete applied at competitive prices.