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NPORS Soil Stabiliser Training (N040)
A soil stabiliser turns ground you would otherwise dig out and cart away into ground you can build on. The rotor mixes lime or cement into the subgrade in place, and the saving is in lorry movements that never happen. Five days for a novice, on your own machine, run when the earthworks programme allows.
Why candidates choose Acadame
What makes our N040 Soil Stabiliser different
About this course
The NPORS N040 Soil Stabiliser category is the operator card for the self propelled machines that mix a binder into the ground in place: a milling and mixing rotor housed under the machine, cutting into the subgrade and blending lime or cement through it in a single pass so that weak or wet ground can carry a road, a platform or a floor slab without being dug out and replaced.
Five days for a novice covers the machine: the carrier, the drive and the tracks or wheels, the rotor and its tools, the mixing chamber and the hood, the binder injection or spreading arrangement where the machine has one, the water or bitumen system where fitted, the depth and levelling controls, and the pre operational checks and defect reporting the handbook requires.
Then the process. Which binder does what, because lime and cement are not interchangeable: lime dries and conditions wet cohesive soils so they can be worked and compacted, and cement builds lasting bearing capacity and resistance to water and frost. Mixing depth and width, overlap between runs, mixing quality and how it is checked, and the sequence around the machine, where a spreader goes first, a grader profiles behind and compactors close the surface to specification. And the health side, which on this machine is the serious one: quicklime and cement dust burn skin and eyes, so handling, dust control, PPE and exposure control run through the whole week.
- The machine: carrier, drive, rotor and tools, mixing chamber and hood, binder and water systems, depth and level controls
- Pre operational and running checks, rotor tool wear, greasing points, defect reporting and what the handbook requires
- Binders and what each does: lime for conditioning wet cohesive soils, cement for lasting bearing capacity
- Setting and holding mixing depth and width, overlapping runs, and judging mixing quality
- Working in the machine train alongside a binder spreader, grader and compactors, and communicating within it
- Health and environmental control: quicklime and cement dust, skin and eye protection, dust suppression and run off
How completing this course helps you
- The NPORS N040 Soil Stabiliser category, registered with NPORS and recognised on sites nationally
- The Red Trained Operator card, or the Blue Competent Operator card where the operator holds the relevant NVQ
- Operators who understand the binder as well as the machine, which is where the health risk sits
- A consistent standard across an earthworks contract, which is what a client, a principal contractor or an insurer asks to see
Who should attend?
Earthworks and civil engineering contractors treating subgrades and capping layers, highways and infrastructure contractors, ground improvement specialists, and plant operators moving across from graders, dozers and rollers. It suits operators who have run a stabiliser or a cold recycler on custom for years as much as new starters, and there is a route for each.
Entry requirements. You should be at least eighteen, fit enough for the work, and able to follow spoken and written English for the theory test, though an interpreter can be arranged on request. No prior card is required, though experience on other earthworks plant helps and often shortens the route. Because the work involves quicklime and cement, any health condition affected by dust or by skin contact with alkaline material is worth raising with us and your own occupational health adviser before the course. For the version of the card that carries the CSCS logo you need a CITB Health, Safety and Environment test pass at Operatives level within the last two years, which we book for you.
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Course content
What you will cover
Classroom on the machine, the binders and the law, then the bulk of the week on the machine mixing treated runs, with testing at the end.
The machine, the binder and the law
- Health and Safety at Work etc. Act 1974 and PUWER 1998 as they apply to soil stabilisation
- COSHH duties for quicklime, hydrated lime and cement, and the health effects of each
- The manufacturer's handbook and the operator's responsibilities under it
- Machine components: carrier, drive, rotor and tools, mixing chamber, binder and water systems, controls
- How stabilisation works: binder selection, mixing depth, moisture content and the effect on bearing capacity
- The machine train: binder spreader ahead, grader behind, compaction to specification, and the timing between them
- Ground conditions, gradients, soft spots and working near excavations and structures
- Environmental control: dust, run off, spillage and the effect of treated material on watercourses
Mixing in place
- Pre operational and running checks, rotor tool condition and defect reporting
- Safe mounting and dismounting, starting up and setting the machine to work
- Manoeuvring and travelling, including on and off transport where that applies
- Setting mixing depth and width and holding them through a run
- Mixing successive runs with correct overlap, and checking the result
- Cleaning down, shutting down and parking the machine safely at the end of the shift
Method of assessment
How the N040 soil stabiliser test works
NPORS assess the category by theory test and practical test. Training and testing run together, with the practical covering checks, manoeuvring, setting up and mixing treated runs to depth and width.
1. Enquiry and group
Tell us how many operators, where, what machine and what material you are treating. Four sit the novice course with one instructor and one machine, six are allowed on the experienced worker test. We quote per group, because the length follows who is on it.
2. Pre course check
We sort who is a novice, who is an experienced worker and who is due a refresher, check whether the CSCS logo version of the card is needed and book the CITB test if it is, then take the details NPORS need to register.
3. Training
Classroom on the machine, the binders and the duties, then the bulk of the week on the machine, ideally on your own site with the material you are actually treating.
4. Theory test
The NPORS theory test covering legislation, COSHH and binders, machine components, mixing depth and quality, and safe operating practice.
5. Practical test
Checks, manoeuvring, setting depth and width and mixing treated runs, assessed against the NPORS test specification by an NPORS registered tester.
6. Registration and card
We register the pass with NPORS and apply for the card, traditional or with the CSCS logo depending on where your operators work.
After the course
The machines either side of the stabiliser
A stabiliser never works alone. There is a spreader in front of it, a grader behind it and rollers closing the surface, and the layer is only as good as the weakest operator in that sequence. Contractors who train the stabiliser operator alone usually find the problem moves rather than disappears. NPORS have categories for the rest of the train, and it is worth mapping the whole earthworks fleet in one go rather than a machine at a time.
Two other things sit alongside this category. Treated ground still has to be inspected and proof rolled before anything is built on it, and where a piling rig or a crane will later stand on that layer, it becomes a working platform with its own design and certification requirements. And if your operators handle bagged or bulk binder by hand at any point, manual handling and COSHH training in their own right are worth more than a paragraph in a method statement.
- N240 Grader for the machine profiling behind the stabiliser
- N214 Road Roller for the compaction that finishes the treated layer
- N215 Dozer where bulk earthworks feed the same operation
- CITB Health, Safety and Environment test booked with us where the CSCS logo version of the card is needed
Build your course
Who is coming, and how many
We do not run these to a timetable. The course is built around your people: how experienced they are and how many of them there are, which is what sets the length and the cost. Pick the mix and we will come back with a date and a price.
The course builder needs JavaScript. Without it, tell us how many people and what experience they have and we will price it up.
N040 Soil Stabiliser FAQs
It mixes a binder into the ground where the ground already is. A rotor under the machine cuts into the subgrade and blends lime or cement through it in one pass, so weak or wet material can carry load instead of being dug out, carted away and replaced with imported stone.
Lime conditions wet cohesive soils: it dries them and makes them workable and compactable, which is soil improvement. Cement builds lasting bearing capacity, volume stability and resistance to water and frost, which is stabilisation proper. Many jobs use both in sequence, and the specification says which.
Five days for a novice, with four candidates to one instructor and one machine. An operator already running a stabiliser normally takes the shorter experienced worker route, where NPORS allow six candidates, and the refresher is shorter again. We confirm the length when we quote.
The machines are closely related and many are sold to do both, but the NPORS category has to match the machine and the work. Tell us what you run and what you treat and we will confirm which category fits rather than issue the wrong one.
Seriously, because quicklime burns. The course covers COSHH duties, what quicklime, hydrated lime and cement each do to skin, eyes and lungs, dust control, the right PPE and what to do about a contamination or a burn. An operator who has not understood that has not passed the theory.
Yes, and it is usually better. Operators train on the machine, the material and the specification they are working to, and nobody loses a week travelling. We need a suitable area for the practical and a machine in a testable condition, which we check before we come.
The Red Trained Operator card, which NPORS issue for two years, or the Blue Competent Operator card valid five years where the operator holds the relevant NVQ. The CSCS logo version of either needs a current CITB Health, Safety and Environment test.
Four on the novice course and the refresher, six on the experienced worker test. Larger groups get sequenced across more than one course, because the ratio is what gives each operator real time on the machine.
NPORS courses are priced per course, not per person. What you are paying for is the instructor, the registered tester and the machine time, so the figure turns on four things: the category, which route your operators need (novice, experienced, conversion or refresher), how many people are coming, and whether we run it on your site or at one of ours. It is also why a squad works out considerably cheaper per head than sending operators out one at a time. Use the course builder on this page: tell it who is coming and it works out how many days the course takes and how many times it has to run, which is what the price is built from. Then ask us and you will get a figure for that exact group rather than a list price with conditions attached.
We run NPORS courses across the UK rather than out of one fixed centre, and for most categories the better answer is that we come to you: your operators are assessed on the machine they will be using anyway, nobody loses a day travelling, and for a group it costs less. If you would rather come to us, we have centres at Trent House in Stoke, Pride Park in Derby, Europa House in Manchester and Kingsway House in Liverpool. Tell us where the work is and we will say honestly which way round makes more sense.
There is no fixed timetable to wait for. NPORS courses here are run to order, which means the dates are built around your programme rather than ours, and a single operator or a full squad can normally be booked in within a couple of weeks. If you have a card about to expire or a start date to hit, say so when you enquire and we will work to it.
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