Slipform machines: what work they do and what the Power Curber 5700-D can build

In short: a slipform machine shapes concrete continuously: the mould moves with the machine and leaves the finished profile behind it, with no fixed forms. With the right mould, one machine can build kerbs, curb and gutter, ditches and channels, sidewalks, cycle paths, safety barriers, bridge parapets, canal lining and special profiles. The Power Curber 5700-D is Power Curbers' three-track offset machine. According to the manufacturer, it slipforms kerb and sidewalk up to 2 m wide in offset, paves up to 3 m in center-pour and builds barriers up to 1.5 m tall. With the MAX package these figures rise to 2.5 m, 3.65 m and 2.5 m. It pours islands with a radius of just 610 mm and works from a stringline or with 3D guidance. For taller profiles or wider paving there are the 5704-D MAX and the 7700. For small kerbs on existing pavement there is the 150 extruder.

What a slipform machine is

In slipforming, the machine carries a mould that is open at the front and back. Concrete enters the mould from a conveyor or a hopper. Vibrators consolidate it inside the mould, and the profile leaves the back already in its final shape. Because there are no fixed forms, the concrete has to stand up on its own as soon as it leaves the mould. That is why slipforming uses low-slump concrete, usually air-entrained.

Power Curbers sums up the advantages over hand forming like this:

• Strength: low-slump concrete is stronger than the more fluid concrete used for hand pouring.
• Production: more metres per day with the same crew or with fewer people.
• Traffic: the job finishes sooner, so traffic is diverted for less time.
• Durability: low-slump, air-entrained concrete resists salt deterioration better.

Curb machines, slipform pavers and extruders

There are three families of machines, and it is worth keeping them apart:

• Curb and multipurpose machines (offset): the mould sits beside the machine, which travels outside the profile it is forming. The 5700-D and the 7700 are examples. They build kerbs, ditches, sidewalks, barriers and canals, and some can also pave in center-pour.
• Slipform pavers: the mould sits between the tracks and the machine paves the full width of a lane. Trapézio represents, for example, the Power Pavers SF-1700 and SF-2700.
• Curb extruders: small machines on tyres that lay small concrete or asphalt kerbs on existing pavement. The Power Curber 150 is an example.

What work a slipform machine can do

Kerbs and curb and gutter

This is the most common application. The mould can produce:

• a plain kerb (called stand-up curb, header curb or ribbon curb in the US);
• monolithic curb and gutter, where the kerb and the gutter pan next to the pavement come out as one piece.

Power Curbers notes that stand-up curb is common on parking lot islands and that curb and gutter is widely used in residential subdivisions. Some mould options avoid hand work after the pour:

• Blockouts: leave room for catch basins and other breaks in the kerb.
• Driveway knives: drop the kerb at driveway entrances.

In the standard specification of Infraestruturas de Portugal (the Portuguese road and rail authority), a concrete kerb must show a 15 cm face above the pavement and be perfectly aligned on straights and curves. The final face height always depends on the design.

Ditches, channels, half-pipes and drainage

A concrete-lined ditch is a continuous, repetitive profile, which makes it typical slipform work:

• V-ditches;
• half-round channels;
• median channels;
• bench ditches;
• lined ditches in mountainous areas.

The Infraestruturas de Portugal standard specification says lined ditches should preferably be cast in situ. For the lining it calls for C16/20 concrete, 0.10 m thick, placed with extrusion equipment or in alternating pours between fixed forms. The foundation is granular, at least 0.10 m thick. Platform ditches and median channels that meet the asphalt are built before the shoulder wearing course. The asphalt then finishes against the ditch, avoiding mortar fillets that tend to crack.

The 5700-D pours ditch liners up to about 2.2 m wide and 610 mm deep in offset. There is one important limit: the trimmer cannot be used on V-ditches. The profile has to be prepared in front of the machine to avoid wasting concrete. With a custom mould, the 5700-D also pours slotted drain curb. An inflated tube is fed into the mould during the pour and pulled out after curing. This leaves a hidden drainage channel below a slot in the gutter.

Sidewalks and cycle paths

The 5700-D pours sidewalk, or monolithic sidewalk and curb, up to about 2 m wide in offset (the 2019 brochure gives 2.1 m for sidewalks). The adjustable offset lets it pour behind an existing kerb and over planter strips. With extensions, the trimmer matches the sidewalk width. Sidewalk moulds can have detachable side plates, to pour against a kerb or to make a second sidewalk width. Moulds wider than about 1.2 m in offset need a sidewalk kit, and a counterweight may be needed.

For cycle paths and wider trails, the 5700-D converts into a center-pour paver:

• Widths: 1.5 m to 3 m, in steps of about 0.5 m (up to 3.65 m with the MAX package).
• Thickness: up to 305 mm, with the hydraulic side plates.
• Conversion: the conveyor and trimmer have to come off. Concrete is dumped straight into a hopper in front of the mould.

The manufacturer presents this setup for golf cart paths and bicycle paths.

Safety barriers and bridge parapets

With a barrier mould, the 5700-D slipforms concrete barrier up to 1.5 m tall, or up to 2.5 m with the MAX package. It builds New Jersey and other profiles, including variable barrier moulds for medians on superelevated curves. These moulds typically weigh between 3630 and 4535 kg and have up to 610 mm of height variation.

At the end of the day, the hydraulic barrier mould lift (1220 mm stroke), together with 914 mm of post extension, lets the crew raise the mould over the steel cage and move the machine out. For parapets and vertical profiles (including tunnels and high-speed rail), there are:

• a parapet sensor mounting kit;
• free-standing stringline stations;
• a 900 kg weight pod.

Choosing the barrier profile and its containment class is a design decision, not a machine one.

No-mow strips and cable barrier

Where cable barrier is used instead of concrete barrier, the 5700-D helps in two ways:

• With a custom mould, it pours a concrete "no-mow" strip under the barrier that reduces vegetation maintenance.
• With the post-hole digger, it drills the post holes: a 305 mm auger, down to 864 mm deep. This attachment requires the Quick Connect mould mount.

Irrigation ditches and canal lining

Power Curbers lists irrigation ditches among the 5700-D's core applications. On large canals the 5700-D can work in several passes, but the manufacturer says this needs custom engineering, with large moulds and long conveyors. Wide canals in a single pass are work for larger machines such as the 7700.

Islands, medians and tight radii

The 5700-D pours islands with a radius of just 610 mm (2 ft). The manufacturer highlights:

• narrow parking lot islands;
• cul-de-sacs;
• parking lot corners.

The minimum turning radius is 610 mm to the left and 6.1 m to the right. Since the mould works on the left side in the base configuration, tight radii are poured on that side. For less extreme radii, the optional hydraulic front grade sensor arm keeps the sensor on the line without manual adjustment.

Special applications

With custom moulds, the 5700-D is also used for:

• Tunnels: curved or flat inverts, rail beds, walls, walkways and profiles for utility conduits.
• Stadium risers: usually two risers per pass. The machine climbs the stand on the risers poured the day before. Power Curbers says the 5700 series has poured stadium risers since the 1996 Atlanta Olympics.
• Agriculture: poultry house foundations, feeding troughs and barn lanes.
• Rehab work: rehab curb (the mould drops into a trench next to existing pavement) and tapered curb over dowels.

Power Curber 5700-D: the essentials

The manufacturer calls the 5700-D the best-selling slipform machine in the world. The 5700 series started in 1985 as a curb and gutter machine only and has gained applications over time. The D version is the current one. The previous 5700-C was built from 2007 to the end of 2019.

Hydraulic offset: the mould where you need it

The mould sits on a hydraulic offset with:

• Lateral travel: 610 mm.
• Vertical travel: 635 mm, of which 406 mm is hydraulic and 228 mm mechanical.

This lets the mould drop into a trench for rehab curb, pour right against existing pavement and come within a few centimetres of catch basins. The offset lock is manual as standard, with a hydraulic option. Pouring is on the left side as standard, with a dual-side pouring option (adds 270 kg).

Trimmer: grading the base before the pour

The trimmer grades the base ahead of the mould:

• Width: 1070 mm, up to 1980 mm with 152, 305 and 610 mm extensions.
• Cut: the ideal cut is 25 to 50 mm, with a maximum of 150 mm.
• Shift: 2030 mm lateral shift, enough to trim for a 1.5 m radius. The 635 mm vertical shift lets it lift over catch basins.

The manufacturer says the trimmer cannot be used on V-ditches or where steel is present.

Auger conveyor

The auger conveyor has the following features:

• Length and diameter: 3.7 m long and 356 mm in diameter.
• Capacity: holds about 0.75 m³ and moves up to 1.5 m³ per minute.
• Movement: it is reversible, pivots, tilts hydraulically and slides 610 mm.

The charge hopper can sit in front of the machine, so the ready-mix truck drives ahead and the machine pours while occupying a single lane.

Guidance: stringline or 3D

As standard, the 5700-D follows a stringline with sensors, including around 610 mm radii. The SlipSmart control system simplifies integration with 3D (stringless) systems from Topcon, Leica and Trimble. 3D work requires all-crawler steering. In the manufacturer's current documentation, all-crawler steering is listed as standard and front-track steering as an option. The 2019 brochure had it the other way round. Confirm the configuration in the quote.

Moulds and mould changes

As standard, the 5700-D has one mould up to 813 mm wide, with a quick-release interchangeable hopper. Wider moulds need an integral hopper. The optional, patented Quick Connect mount allows mould changes in as little as 5 minutes. Barrier moulds use a manual mount. Power Curbers builds custom moulds for special profiles. The most common mould options are:

• blockouts;
• bolt-on extensions;
• detachable toe;
• driveway knives, rotating or side-entry;
• removable or hydraulic side plates;
• open front;
• rebar ports. No radius can be poured while rebar is fed into the mould.

Engine, tracks and transport

The engine is a 97 kW (130 hp) Cummins QSB4.5, Tier 4 final. Where regulations allow, a Tier III engine is available. The machine runs on three tracks with 305 mm steel pads, with polyurethane pads as an option. Pouring speed is up to 15 m/min (10.5 m/min with the MAX package).

The machine weighs about 11,200 kg, plus 340 kg with Quick Connect and 1,135 kg with the MAX package. It measures about 6.1 m long, 2.6 m wide and 2.5 m high (without the exhaust stack).

The manufacturer stresses that it travels at US legal width (2.59 m) without a low-boy trailer. In Portugal the general width limit is 2.55 m, so the load may need a special transport permit (AET). Machinery hauliers usually hold an annual permit. See our guide to heavy machinery transport (in Portuguese).

What the 5700-D does not do, or does with limits

• Tall barriers and parapets: the 5700-D goes up to 1.5 m tall, or 2.5 m with the MAX package. For tall barriers and parapets that need more stability there is the 5704-D MAX, a fourth-track add-on for the 5700-D. The 7700 builds barriers up to 2.4 m.
• Wide paving: in center-pour, the 5700-D paves up to 3 m (3.65 m with the MAX package). Roadways and other wide pavements are work for the 7700 (up to 6 m) or a slipform paver.
• V-ditches: the trimmer does not work on V-ditches or where steel is present. The base has to arrive already prepared.
• Radii with rebar: no radius can be poured while rebar is fed into the mould.
• Right-hand radii: the minimum right-hand radius is 6.1 m. Tight radii are poured on the mould side.
• Large canals: only in several passes and with custom engineering.
• Small kerbs on existing pavement: here an extruder such as the 150 may be more practical.

5700-D, 5704-D MAX, 7700 or 150: which to choose

The figures in the table come from Power Curbers' product pages and brochures. The right choice depends on the profiles you will build most often, the maximum widths and heights, and the space available on site.

What the job site needs

• A base prepared and compacted to grade: the trimmer takes off the last few centimetres, but it does not replace earthworks.
• A well-set stringline or a validated 3D model: the finished profile is only as good as the reference the machine follows.
• Concrete suited to slipforming: low slump and air-entrained. Power Curbers publishes reference mixes for curb and gutter and for barrier, but the final mix is set by the design and the batching plant.
• A steady concrete supply: the manufacturer says a steady supply is often the biggest factor in daily production.
• Crew: according to the manufacturer, an operator, a chute man and four to six people behind the machine.
• Finishing and curing: a broom finish or other specified texture, plus curing compound.

On production, Power Curbers uses 2,000 ft (about 600 m) per day of 24-inch (about 610 mm) curb and gutter as an example, calling it "a good average". It explains that the figure varies with the type of job, base preparation and how quickly concrete arrives. For the manufacturer, a machine pays off from about 6,000 to 7,500 m of kerb per year.

How Trapézio de Prismas can help

Trapézio de Prismas is the official Power Curbers dealer in Portugal.

• New machines: sales of new Power Curbers machines, including the 5700-D, the 7700 and the 150, with help choosing the configuration and the moulds for the profiles you will build.
• Moulds and parts: supply of moulds and Power Curbers parts.
• Technical support: service and repair and access to Power Curbers manuals.
• Used machines: used machines, when available.
• Quote or demo: request a quote or a demonstration, or contact us.