Maharashtra HSC Construction Technology (Vocational) flashcards

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

Modular brick size

A standard modular brick measures 190 × 90 × 90 mm; with a 10 mm mortar joint the module becomes 200 × 100 × 100 mm, simplifying wall dimensioning.

Initial setting time of OPC

Ordinary Portland cement must have an initial setting time of not less than 30 minutes, allowing time for mixing, transport, placing and compaction before stiffening begins.

Le Chatelier apparatus test

This test measures cement soundness, detecting expansion caused by uncombined free lime. Unsound cement expands after setting and causes cracking in hardened concrete or plaster.

Seasoning of timber

Seasoning reduces timber moisture content to about 10-12 percent for carpentry work. It lowers weight, improves strength and reduces shrinkage and warping after installation.

Long wall short wall method

An estimating method where long walls are measured centre-to-centre plus one wall thickness and short walls centre-to-centre minus one wall thickness, giving separate lengths for each direction.

Prismoidal rule formula

Volume = d/3 × [first + last ordinate + 4 × (sum of even ordinates) + 2 × (sum of odd ordinates)]. It is more accurate than the trapezoidal rule for irregular cross-sections.

Representative fraction of scale

The ratio of drawing length to actual length, written as 1:50 or 1:100. A scale of 1:50 means one millimetre on paper represents fifty millimetres on the ground.

Height of instrument

HI equals the reduced level of a point plus its backsight reading. Subtracting an intermediate or foresight reading from HI gives the reduced level of the new station.

Rise and fall arithmetic check

In level booking, the sum of backsights minus the sum of foresights must equal the sum of rises minus the sum of falls, and also equal last RL minus first RL.

Curvature and refraction correction

Combined correction equals 0.0673 times the square of the distance in kilometres, giving metres. It is applied as a negative correction to staff readings in precise levelling.

Reciprocal ranging

A ranging technique used when two stations are not intervisible, such as across a hill. Two chainmen alternately align intermediate points until both ends line up correctly.

Rankine minimum foundation depth

Depth d = (q/γ) × [(1 − sin φ)/(1 + sin φ)]², where q is bearing capacity, γ unit weight and φ angle of repose. It ensures the soil is not overstressed.

English bond versus Flemish bond

English bond alternates full header and stretcher courses; Flemish bond alternates header and stretcher within each course. English bond is stronger and preferred for thick walls.

Total float of an activity

Total float equals latest start minus earliest start, or latest finish minus earliest finish. Activities with zero float lie on the critical path and cannot be delayed.

Formwork striking time for slab soffit

For ordinary Portland cement under normal conditions, slab soffit formwork may be removed after about three days, with props retained longer for long spans or heavy loading.

Section modulus of rectangle

For a rectangular section of width b and depth d, the section modulus Z equals bd²/6. Bending stress is then found from sigma = M/Z.

Target mean strength

Target mean strength equals characteristic strength plus 1.65 times the standard deviation. This margin ensures no more than a small permitted percentage of test results fall below the grade.

Slump cone dimensions

The standard slump cone has a top diameter of 100 mm, bottom diameter of 200 mm and height of 300 mm, used to measure concrete workability on site.

Modulus of rupture of concrete

Flexural strength, or modulus of rupture, is approximately 0.7 times the square root of the characteristic cube strength in N/mm², used in crack-width and deflection checks.

Superplasticiser function

A superplasticiser is a high-range water reducer that greatly improves workability at the same water-cement ratio, or allows significant water reduction while maintaining slump.

Water seal depth in traps

A trap retains a water seal of about 50 to 75 mm. This seal blocks sewer gases from entering the building while allowing wastewater to flow through.

Soil pipe versus waste pipe

A soil pipe carries sewage from water closets and urinals; a waste pipe carries sullage from sinks, basins and baths. Both connect to the drainage system through traps.

RCCB residual current rating

A 30 mA residual current device protects people against electric shock by tripping quickly when leakage current to earth exceeds the rated sensitivity, typically within 30 milliseconds.

Self-cleansing velocity in drains

A velocity of about 0.6 to 0.75 metres per second keeps solids moving and prevents silt deposition in drainage pipes laid at the designed gradient.

Hierarchy of hazard control

Controls ranked from most to least effective: elimination, substitution, engineering controls, administrative controls, then personal protective equipment as the last defence.

Trench spoil edge distance

Excavated spoil should be kept at least 0.6 to 1 metre from the trench edge to reduce surcharge loading on the sides and prevent collapse onto workers below.

CPR compression to breath ratio

For adult first aid, deliver 30 chest compressions followed by 2 rescue breaths, repeating the cycle until help arrives or the casualty recovers breathing.

Break-even quantity formula

Break-even quantity equals fixed cost divided by contribution per unit, where contribution is selling price minus variable cost. At this volume total revenue equals total cost.

Earnest money deposit

A sum submitted with a tender to show serious intent, usually a percentage of the estimated cost. It is refunded to unsuccessful bidders and adjusted against security deposit for the winner.

Item rate contract

A contract in which the contractor quotes rates per item of the bill of quantities, and payment is made for actual measured quantities executed at those agreed rates.

Bar bending hook length

A standard 180-degree hook extends 9 times the bar diameter, while a stirrup hook extends 8 times the diameter. These lengths are added in the bar bending schedule.