Concrete and groundworks calculators.Concrete volumes, mixes, rebar, excavation, sub-base, drainage and site maths.

Concrete volumes

A = L W

Concrete volumesStrip footing volume

V = L \frac{W}{1000} \frac{D}{1000}

Concrete volumesTrench fill foundation volume

D_{f} = D_{t} - g

Concrete volumesPad foundation volume

V = n L W \frac{D}{1000}

Concrete volumesCircular column or hole volume

V_{1} = \frac{π (d / 1000)^{2}}{4} h

Concrete volumesSolid concrete steps volume

V_{s} = \frac{B G R N (N + 1) / 2}{10^{6}}

Ordering and mixing

Ordering and mixingReady-mix order quantity with waste

V_{w} = V (1 + \frac{w}{100})

Ordering and mixingSite mix materials: cement, sand and aggregate

V_{d} = f V

Ordering and mixingWater–cement ratio and mixing water

M_{c} = C V

Ordering and mixingAll-in ballast and cement quantity

V_{d} = f V

Reinforcement

ReinforcementRebar weight per metre and total weight

m = \frac{d^{2}}{162}

ReinforcementNumber of bars at a given spacing

L_{n} = 1000 L - 2 c

ReinforcementTension lap length (Eurocode 2)

η_{2} = 1 (φ ≤ 32; otherwise (132 - φ) / 100)

ReinforcementMesh sheets for an area, with laps

n_{a} = \max (1, ⌈ \frac{L - l_{p} / 1000}{S_{L} - l_{p} / 1000} ⌉)

Cover, formwork and curing

Cover, formwork and curingNominal cover check (Eurocode 2 / BS 8500)

c_{\min} = \max (φ, c_{d u r}, 10)

Cover, formwork and curingConcrete pressure on formwork (CIRIA Report 108)

K = {(\frac{36}{T + 16})}^{2}

Cover, formwork and curingConcrete strength gain with age and temperature (Eurocode 2)

t_{T} = t \exp (- (\frac{4000}{273 + T} - 13.65))

Post holes

Post holesPost mix (Postcrete) bags per hole

V_{h} = \frac{π d^{2}}{4} \frac{h}{10^{6}}

Excavation and muck-away

Excavation and muck-awayExcavation volume: rectangular pit, slab dig or trench

V = N \times L \times W \times D

Excavation and muck-awayExcavation with battered sides (prismoidal formula)

L_{t} = L + 2 \times k D

Excavation and muck-awayBulked spoil volume and skip loads

V_{b} = V \times (1 + \frac{s}{100})

Excavation and muck-awayMuck-away tonnes and lorry loads

T = V \times ρ

Sub-base and aggregates

Sub-base and aggregatesType 1 sub-base tonnes

V_{c} = \frac{A \times t}{1000}

Sub-base and aggregatesSand blinding tonnes

V = \frac{A \times t}{1000}

Sub-base and aggregatesGravel and pea shingle tonnes

V = \frac{A \times t}{1000}

Sub-base and aggregatesPipe bedding and surround (pea gravel) per run

A_{b} = \frac{B (b + D_{o} + c)}{1000000} - \frac{π {D_{o}}^{2}}{4000000}

Drainage

DrainageDrain fall and downstream invert level

F_{l} = \frac{L}{G} \times 1000

DrainageDrain gradient from two invert levels

F_{l} = ({IL}_{1} - {IL}_{2}) \times 1000

DrainagePipe full-bore capacity (Colebrook–White)

D_{m} = \frac{D}{1000}

DrainagePipe full-bore capacity (Manning)

D_{m} = \frac{D}{1000}

Soakaways

SoakawaysSoil infiltration rate from a BRE 365 pit test

V_{p} = \frac{L W d}{2}

SoakawaysSoakaway pit depth (BRE Digest 365)

I = \frac{A \times R}{1000}

Levels and earthworks

Levels and earthworksManhole or chamber depth and number of rings

H = CL - IL

Levels and earthworksCut and fill from a 3 × 3 grid of levels

H_{m} = \frac{h_{1} + h_{3} + h_{7} + h_{9} + 2 (h_{2} + h_{4} + h_{6} + h_{8}) + 4 h_{5}}{16}

Retaining and trench safety

Retaining and trench safetyActive earth pressure on a retaining wall (Rankine)

K_{a} = \frac{1 - \sin φ}{1 + \sin φ}

Retaining and trench safetyTrench battered back for safety: top width and extra dig

W_{t} = B + \frac{2 D}{\tan θ}

Plant and pricing

Plant and pricingPlant hire and fuel cost

F_{u} = h \times c

Plant and pricingGroundworks job price with VAT

N = L_{d} \times D_{r} + M_{c} \times (1 + \frac{μ}{100}) + P_{l} + W_{d}

Concrete and groundworks calculators.Concrete volumes, mixes, rebar, excavation, sub-base, drainage and site maths.

Concrete volumes

Ordering and mixing

Reinforcement

Cover, formwork and curing

Post holes

Excavation and muck-away

Sub-base and aggregates

Drainage

Soakaways

Levels and earthworks

Retaining and trench safety

Plant and pricing

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