Words explained — AIM Site Ops

Plain-English meaning of the site terms used across this app. Search a word, or scroll the groups. New terms the AI spots in site documents are proposed here for a supervisor to approve.

CDM & the paperwork

CDM 2015The Construction (Design and Management) Regulations 2015 — the main law for running a construction job safely.

CPPConstruction Phase Plan — the site's live health-and-safety plan: how this job will be built safely. Must be in place before work starts (CDM Reg 12).

PCIPre-Construction Information — the risks and info the client and designer hand over before the job starts (existing services, asbestos, ground conditions).

RAMSRisk Assessment + Method Statement — the safe step-by-step way to do a task, and the hazards it controls.

Method statementThe agreed step-by-step sequence for doing a task safely.

Risk assessmentThe list of what could go wrong on a task and the controls put in place to stop it.

POWRAPoint Of Work Risk Assessment — a quick check by the crew of the actual conditions right before they start a task.

Permit to workA signed authorisation to do a high-risk task (dig, hot works, confined space) under set controls.

ITPInspection & Test Plan — the checklist of what gets checked and who signs, e.g. before a concrete pour.

Hold pointA step where work stops until someone inspects and signs it off.

RFIRequest For Information — a formal written question to the designer.

Toolbox talkA short on-site safety briefing on one topic, given before the work.

Near missSomething that could have caused injury or damage but did not. Reported so it can be fixed before it does.

RIDDORThe rules for reporting serious accidents, injuries and dangerous events to the HSE.

SFAIRP / ALARPSo Far As Is Reasonably Practicable / As Low As Reasonably Practicable — doing what is sensible and proportionate to control a risk, not gold-plating everything.

Who is who (CDM roles)

ClientThe organisation the work is for. Carries the top-level CDM duties.

Principal Designer (PD)Plans and coordinates health and safety in the design and planning stage.

Principal Contractor (PC)Runs health and safety on site during construction — AIM's role on its own jobs.

DesignerAnyone who prepares or changes a design, including specifying a beam, foundation or temporary works.

TWC / TWSTemporary Works Coordinator / Supervisor — the people who control the temporary works (props, shutters, batters).

Banksman / slingerThe trained person who directs plant movements and lifts.

The hole and the ground

FormationThe ground surface at the bottom of the dig that you build off.

BlindingA thin (~50mm) layer of weak concrete over the formation to give a clean, level, firm surface to set steel on. Not structural.

Over-digDug deeper or wider than the drawing said.

BatterA dig face sloped back at an angle instead of vertical, so it will not collapse.

BenchingCutting the dig face into steps or shelves rather than one slope.

SurchargeExtra weight near the top edge of a dig (spoil heap, plant) that pushes the face to collapse.

Shoring / trench boxTemporary support (props or a steel box) that holds a trench or excavation face from collapsing while people work in it.

FootprintThe plan outline or area of a structure on the ground.

The concrete and steel

Lean / mass concretePlain, weak, unreinforced concrete used as fill or blinding.

RC grade (e.g. RC32/40)A reinforced-concrete mix; the numbers are its strength.

Slump / S3 / S4How runny the wet concrete is. S4 is wetter and flows more, for getting round dense steel.

KickerA small concrete upstand (~100-150mm) cast on top of the base in the same pour, that the wall is built off. Gives the shutter a clean lip and keeps water from tracking along the base-wall joint.

WaterstopA strip cast across a joint to block water getting through it.

CoverThe thickness of concrete between the steel and the surface — it stops the steel rusting.

Rebar / cageSteel reinforcement bars, tied together into a 3D cage.

Cast-insAnything buried in the pour that cannot be added afterwards (ducts, waterstops, earth tails).

Cold jointAn unplanned join where the first concrete set before the next was placed against it — a weak line and a leak path.

HoneycombGaps in set concrete where it did not pack round the steel. Looks like a honeycomb and leaks.

Cube testSample cubes crushed at 7 and 28 days to prove the concrete strength.

CuringKeeping fresh concrete damp and protected for days so it hardens without cracking.

Health hazards

COSHHControl Of Substances Hazardous to Health — the rules for using and storing dangerous substances (fuels, resins, dusts) safely.

HAVSHand-Arm Vibration Syndrome — nerve and circulation damage from too much time on vibrating tools (breakers, grinders). Exposure is tracked and limited.

Silica / RCSRespirable Crystalline Silica — the fine dust from cutting stone, concrete and brick. Causes lung disease. Control with water or extraction, plus masks.

NoiseLoud plant and tools damage hearing over time. Controlled by distance, quieter kit and ear protection.

Manual handlingLifting and carrying by hand — a leading cause of back and muscle injury. Plan the lift, use kit, get help.

AsbestosA deadly fibre found in older buildings and ground. Never disturb suspected material — stop and report.

Confined spaceA space that is enclosed enough for fumes to build up or air to run out (deep pits, chambers, tanks). Needs gas testing and a top-man.

Plant and lifting

PUWERThe rules that say work equipment and plant must be safe, maintained and used by trained people.

LOLERThe rules for lifting equipment and lifting operations — planning, gear and examination.

Thorough examinationA statutory inspection of lifting gear and some plant by a competent examiner, at set intervals. Out of date = out of use.

SWL / WLLSafe Working Load / Working Load Limit — the most a crane, sling or shackle is allowed to lift. Never exceed it.

Exclusion zoneA barriered-off area no one enters — around a lift, a slewing machine, or a pump boom.

MEWPMobile Elevating Work Platform — a cherry-picker or scissor lift for working at height.