Mongolia Certified Construction Engineer flashcards

34 cards. Read the term and the definition here. The deck at the top of this page is optional.

Characteristic concrete strength

The 28-day strength below which no more than 5% of test results are expected to fall, determined on standard-cured 150 mm cubes or 150×300 mm cylinders; it is the basis of the C-class designation.

Water-cement ratio

The mass ratio of free water to cement in a concrete mix. It primarily governs strength and permeability: lower ratios give stronger, more durable concrete but reduce workability, requiring admixtures or more cement.

Slump test

A workability test using a 300 mm cone filled in three layers and lifted vertically; the measured drop of the concrete indicates consistency. It is unsuitable for very dry or highly fluid mixes.

Cube acceptance criteria

For a group of three cubes, the mean strength must be at least the characteristic value plus 4 MPa, and no single result may fall below the characteristic value minus 4 MPa.

Ultimate limit state combination

Design action combining permanent loads at partial factor 1.35 and the leading variable action at 1.5, with accompanying variable actions at 1.5 times their combination factor psi-zero.

Balanced section ratio

The reinforcement ratio at which concrete crushing and steel yielding occur simultaneously. Sections below it fail ductilely with warning; above it, failure is brittle and must be avoided.

Effective span

The distance used in structural analysis between points of zero moment, typically clear span plus effective depth or support width, whichever is smaller, and never exceeding the clear span plus support width.

Buckling curve

A curve relating reduction factor chi to reduced slenderness for steel compression members; the curve class (a0 to d) reflects section type, manufacturing, and axis of buckling.

Critical path float

Activities on the critical path have zero total float, meaning any delay in their start or duration directly extends the project completion date unless the network logic is changed.

Formwork removal strength

Side forms can usually be struck at about 2.5 MPa, while soffits require 70–100% of design strength depending on span, verified by maturity or companion cube testing.

Vibrator spacing rule

Internal vibrators compact concrete within roughly 0.3–0.5 m radius; insertion points are spaced so zones overlap, and the vibrator penetrates the layer below by 5–10 cm.

Winter concreting protection

Fresh concrete is placed at no less than +5 degrees Celsius and kept from freezing until it attains about 5 MPa, the threshold below which ice formation destroys the cement matrix.

Bearing capacity equation

Terzaghi's expression for a strip footing: ultimate pressure equals cohesion times Nc plus surcharge times Nq plus half times unit weight times width times N-gamma.

Plasticity index

The difference between liquid limit and plastic limit. Values below 7 indicate low plasticity, 7 to 17 medium, and above 17 high plasticity, helping classify clays and silts.

Effective stress principle

Total vertical stress minus pore water pressure. It controls soil strength and compression; a rising water table lowers effective stress and therefore bearing capacity.

Critical hydraulic gradient

The upward seepage gradient at which effective stress becomes zero and soil loses all strength, causing boiling or quick conditions; it equals (Gs minus 1) divided by (1 plus void ratio).

Frost penetration depth

The maximum depth to which soil freezes in winter. Footings must extend below it or be insulated, otherwise frost heave lifts and cracks lightly loaded structures.

Concealed works act

A signed inspection record confirming that reinforcement, waterproofing, or embedded services were checked before being covered; works lacking such acts cannot be accepted at handover.

Fire resistance class

A rating in minutes for load-bearing capacity (R), integrity (E), and insulation (I) of a building element under standard fire exposure, selected according to building function and height.

Building permit sequence

Design documentation, expert technical review, construction permit, construction with technical supervision, as-built acceptance by the state commission, then state registration of the completed building.

Retention money

A percentage, commonly 5–10%, withheld from each interim payment and released after acceptance or the defect liability period, securing the employer against uncorrected defects.

Cost performance index

Earned value divided by actual cost. A value below one indicates the work performed cost more than budgeted, so the project is overspending relative to progress.

Price adjustment formula

A contract clause recalculating the contract price using weighted indices for labor and materials, protecting both parties from inflation during long construction periods.

Variation order

A written instruction changing scope, quantity, or timing. It must be issued before execution and valued using contract rates, then analogous rates, then a fair valuation.

Trench shoring threshold

Excavations deeper than about 1.5 m require shoring, benching, or safe slopes; spoil and plant are kept at least 1 m from the edge, with ladders for access.

Fall arrest anchor rule

Personal fall arrest systems use a full-body harness attached to an anchor point above the worker, so the free-fall distance and swing hazard are minimized in a fall.

Hot work permit

Authorization for welding, cutting, or grinding that specifies fire precautions, a fire watch continuing at least one hour after work ends, and suitable extinguishers nearby.

RCD protection value

Residual current devices rated at 30 milliamps protect socket and hand-held tool circuits on site, disconnecting supply fast enough to prevent fatal electric shock.

Legionella storage temperature

Hot water is stored at no less than 60 degrees Celsius to kill Legionella bacteria, while a thermostatic mixing valve limits delivery at outlets to about 50–55 degrees to prevent scalding.

Self-cleansing velocity

The minimum mean flow velocity in a gravity sewer, about 0.7 m/s at design flow, that keeps solids suspended and prevents deposition; upper limits near 5 m/s avoid abrasion.

Voltage drop limit

The permitted reduction in voltage along a circuit, commonly 3% for lighting and 5% for other loads, checked alongside current-carrying capacity when selecting cable cross-section.

Conflict of interest

A situation where an engineer's financial or personal interest could bias professional judgment. It must be disclosed, and the engineer should withdraw from the affected decision.

Waste hierarchy

The preferred order of waste management: prevent generation, reuse materials, recycle, recover energy, and only then dispose. Hazardous wastes such as oils are segregated separately.

Silt control on site

Runoff from excavations and washing is passed through settling tanks or traps before discharge, preventing suspended solids from polluting watercourses and drains.