Introduction The Company Links News Contact Details
> Tables &
   Memoranda
 

      Resources:
Tables &
Memoranda
Building
Regulations
Useful
Addresses
Professional
Bodies
Kenward
Gallery

Vacancies:
Click for details

Tables & Memoranda

For your easy reference we've brought together on one page the conversions, formulae and trade memoranda most commonly used by groundworks contractors and that may well be helpful to other visitors. Bookmark this page and click on the links below to go straight to the table you are looking for but please note we cannot be held responsible for the incorrect use thereof or for any consequential loss arising therefrom!
 
Conversion Tables
 
LENGTH
                               
Unit   Conversion Factors
                       
Millimetre mm 1 in = 25.4 mm   1 mm = 0.0394 in
Centimetre cm 1 in = 2.54 cm   1 cm = 0.3937 in
Metre m 1 ft = 0.3048 m   1 m = 3.2808 ft
    1 yd = 0.9144 m       = 1.0936 yd
Kilometre km 1 mile = 1.6093 km   1 km = 0.6214 mile
                       
   
Note:
 1 cm = 10 mm   1 ft = 12 in
      1 m = 1000 mm   1 yd = 3 ft
    1 km = 1000 m   1 mile = 1760 yd
                       
 
 (Return to Page Top)
 
AREA
                                 
Unit   Conversion Factors
                       
Square Millimetre mm 2 1 in 2 = 645.2 mm 2   1 mm 2 = 0.0016 in 2
Square Centimetre cm 2 1 in 2 = 6.4516 cm 2   1 cm 2 = 1.1550 in 2
Square Metre m 2 1 ft 2 = 0.0929 m 2   1 m 2 = 10.764 ft 2
    1 yd 2 = 0.8361 m 2     m 2 = 1.1960 yd 2
Square Kilometre km 2 1 mile 2 = 2.590 km 2   1 km 2 = 0.3861 mile 2
                       
   
Note:
 1 cm 2 = 100 mm 2   1 ft 2 = 144 in 2
      1 m 2 = 10000 cm 2   1 yd 2 = 9 ft 2
    1 km 2 = 100 hectares   1 acre = 4840 yd 2
              1 mile = 640 acres
                           
 
 (Return to Page Top)
 
VOLUME
                                 
Unit   Conversion Factors
                       
Cubic Centimetre cm 3 1 cm 3 = 0.0610 in 3   1 in 3 = 16.387 cm 3
Cubic Decimetre dm 3 1 dm 3 = 0.0353 ft 3   1 ft 3 = 28.329 dm 3
Cubic Metre m 3 1 m 3 = 35.3147 ft 3   1 ft 3 = 0.0283 m 3
    1 m 3 = 1.3080 yd 3   1 yd 3 = 0.7646 m 3
Litre l 1 l = 1.76 pint   1 pint = 0.5683 l
      = 2.113 US pint       = 0.4733 US l
                       
   
Note:
 1 dm 3 = 1000 cm 3   1 ft 3 = 1.728 in 3
      1 m 3 = 1000 dm 3   1 yd 3 = 27 ft 3
    1 l = 1 dm 3            
              1 pint = 20 fl oz
              1 gal = 8 pints
                       
 
 (Return to Page Top)
 
MASS
                                 
Unit   Conversion Factors
                       
Milligram mg 1 mg = 0.0154 grain   1 grain = 64.935 mg
Gram g 1 g = 0.0353 oz   1 oz = 28.350 g
Kilogram kg 1 kg = 2.2046 lb   1 lb = 0.4536 kg
Tonne t 1 t = 0.9842 ton   1 ton = 1.016 t
                       
   
Note:
 1 g = 1000 kg   1 oz = 437.5 grains
      1 kg = 1000 kg   1 lb = 16 oz
    1 t = 1000 kg   1 stone   14 lb
                       
              1 cwt = 112 lb
              1 ton = 20 cwt
                       
 
 (Return to Page Top)
 
FORCE
                                 
Unit   Conversion Factors
                       
Newton N 1 lbf = 4.448 N   1 lbf = 4.448 N
Kilonewton kN 1 lbf = 0.00445 kN   1 lbf = 0.00445 kN
Meganewton MN 1 tonf = 0.9964 MN   100 tonf = 0.9964 MN
                       
              1 kgf = 9.807 N
              1 tonf = 9.964 kN
                       
 
 (Return to Page Top)
 
PRESSURE & STRESS
                              
Unit   Conversion Factors
                   
Kilonewton per square metre kN/m 2 1 lbf/m 2 = 6.895 kN/m 2        
    1 bar = 100 kN/m 2        
Meganewton per square metre MN/m 2 1 tonf/ft 2 = 107.3 kN/m 2    = 0.1073 MN/m 2
    1 kgf/cm 2 = 98.07 kN/m 2        
    1 lbf/ft 2 = 0.04788 kN/m 2        
                   
 
 (Return to Page Top)
 
COEFFICIENT OF CONSOLIDATION (Cv) or SWELLING
                                 
Unit   Conversion Factors
                       
Square metre per year m 2 /year 1 cm 2 /s = 3.154 m 2 /year            
    1 ft 2 /year = 0.0929 m 2 /year            
                       
 
 (Return to Page Top)
 
TEMPERATURE
                                 
Unit   Conversion Factors
                       
Degree Celsius °C °C = 5/9 x (°F - 32) kN/m 2          °F = (9 x °C)/5 + 32    
                       
 
(Return to Page Top)
Formulae
 
TWO DIMENSIONAL FIGURES
                             
Figure Formulae to calculate area
                   
Square (side)2
   
Rectangle Length x breadth
   
Triangle ½ (base x height)
  OR
  v(s(s-a)(s-b)(s-c) where a, b and c are the lengths of the three sides and
s=(a+b+c)/2
  OR
  a2 = b2 + c2 - (2b ccosA) where A is the angle opposite side a
   
Hexagon 2.6 x (side)2
   
Octagon 4.83 x (side)2
   
Trapezoid height x ½ (base + top)
   
Circle
 		 3.142 x radius2 or 0.7854 x diameter2 (circumference = 2 x 3.142 x radius
or 3.142 x diameter)
   
Sector of a circle ½ x length of arc x radius
   
Segment of a circle area of sector - area of triangle
   
Ellipse 3.142 x AB (where A = ½ x height and B = ½ x length)
   
Bellmouth 3/14 x radius2
                   
 
 (Return to Page Top)
 
THREE DIMENSIONAL FIGURES
                             
Figure Formulae to calculate volume Formulae to calculate surface area
                   
Prism Area of base x height Circumference of base x height
     
Cube (side)3 6 x (side)2
     
Cylinder 3.142 x radius2 x height 2 x 3.142 x radius x (height - radius)
     
Sphere 4/3 x 3.142 x radius3 4 x 3.142 x radius2
     
Segment of a sphere [(3.142 x h) x (3 x r2 + h2)] / 6
 		 2 x 3.142 x r x h
 
     
Pyramid 1/3 of area of base x height 1/2 x circumference of base x slant height
     
Cone 1/3 x 3.142 x radius2 x h 3.142 x radius x slant height
     
Frustrum of a pyramid
 		 1/3 x height [A+B+v(AB)] where A is the area of the large end and B is the area of the small end 1/2 x mean circumference of base x slant height
 
     
Frustrum of a cone
 		 [1/3 x 3.142 x height (R2 + r2 +R x r)] where R is the radius of the large end and r is the radius of the small end 3.142 x slant height x (R + r)
 
 
                   
 
 (Return to Page Top)
 
OTHER FORMULAE
                             
Formulae Description
                   
Pythagoras' Theorem
 		 A2 = B2 + C2 where A is the hypotenuse of a right angled triangle and B & C are the two adjacent sides
   
Simpson's rule Volume = x/3 [(y1 +yn) + 2(y3 + y5) + 4(y2 + y4)]
  The volume to be measured must be represented by an odd number of cross sections (y1 - yn) taken at fixed intervals (x), the sum of the areas at even numbered cross sections (y2, y4 etc.) is multiplied by 4 and the sum of the areas at odd numbered imtermediate cross sections (y3, y5, etc.) is multiplied by 2, and the end cross sections (y1 and yn) taken once only. The resulting weighted average of these areas is multiplied by 1/3 of the distance between the cross sections (x) to give the total volume.
   
Trapezoidal rule
 		 (0.16 x [Total length of trench] x [area of first section x 4 times area of middle section + area of last section])
   
Note:
 
 		 Both Simpson's Rule and Trapezoidal Rule are useful in accurately calculating the volume of an irregular trench, or similar longtitudinal earthworks movement e.g. road construction
                   
 
(Return to Page Top)
Trade Memoranda
 
WEIGHTS OF AGGREGATES
                     
Material   kg/m3 Material   kg/m3
           
Ashes   610 Lime Chalk (lump) 704
Cement (Portland) 1600   Ground 761
Chalk   2406   Quick 880
Chippings (stone) 1762 Sand Dry 1707
Clinker (furnace) 800   Wet 1831
Clinker (concrete) 1441 Water   1000
Ballast or stone   2241 Shale/Whinestone   2637
Pumice   640 Broken stone   1709
Gravel   1790 Pitch   1152
           
 
 (Return to Page Top)
 
WEIGHTS OF BRICKWORK & BLOCKWORK
                     
Brickwork Type kg/m3 Blockwork Type kg/m3
           
  Common Fletton 1822   Aerated 650
  Glazed Brick 2080   Dense Concrete 1800
  Staffordshire Blue 2162   Lightweight Concrete 1200
  Red Engineering 2240   Pumice Concrete 1080
  Concrete 1841      
           
 
 (Return to Page Top)
 
BULKAGE OF SOILS AFTER EXCAVATION
             
Soil Type Approximate bulk of 1 m3 after excavation
   
Vegetable soil & loam 25 - 30%
Soft clay 30 - 40%
Stiff clay 10 - 15%
Gravel 20 - 25%
Sand 40 - 50%
Chalk 40 - 50%
Rock, weathered 30 - 40%
Rock, unweathered 50 - 60%
   
   
   
 
 (Return to Page Top)
 
COMMON SITE MIXED CONCRETE MIXES FOR VARIOUS TYPES OF WORK
                         
     Mix      Class of work suitable for    Cement      Sand      Coarse
Aggregate  		    No of 25kg bags of cement per m3 of combined aggregates     
                         
  1:3:6   Roughest type of mass concrete such as footings, road haunchings 300mm thick   208   905   1509   8  
                         
  1:2.5:5   Mass concrete of better class than 1:3:6 such as bases for machinery, walls below ground   249   881   1474   10  
                         
  1:2:4   Most ordinary uses of concrete such as mass walls above ground, road slabs etc. and general reinforced work   304   889   1431   12  
                         
  1:1.5:3   Watertight floors, pavements, and walls, tanks, pits, steps, paths, surface of two course roads, reinforced concrete where extra strength is required   371   801   1336   15  
                         
  1:1:2   Work of thin section such as fence posts and small precast work   511   720   1206   21  
                         
 
 (Return to Page Top)
 
BAR REINFORCEMENT - CROSS SECTIONAL AREA & MASS
               
Nominal sizes (mm)   Cross sectional area (mm2)   Mass per metre run (kg)  
     
6 28.3 0.222
8 50.3 0.395
10 78.5 0.616
12 113.1 0.888
16 201.1 1.579
20 314.2 2.466
25 490.9 3.854
32 804.2 6.313
40 1256.6 9.864
50 1963.5 15.413
     
 
 (Return to Page Top)
 
FABRIC REINFORCEMENT - PREFERRED RANGE OF FABRIC TYPES & STOCK SHEET SIZES
                             
Fabric reference    Mass    Longitudinal wires Cross wires
                   
    Nominal
wire size		   Pitch Area Nominal
wire size		      Pitch Area
  kg/m2 (mm)   (mm) (mm2/m) (mm)   (mm) (mm2/m)
Square mesh                  
A393 6.16 10   200 393 10   200 393
A252 3.95 8   200 252 8   200 252
A193 3.02 7   200 193 7   200 193
A142 2.22 6   200 142 6   200 142
A98 1.54 5   200 98 5   200 98
                   
Structural mesh                  
B1131 10.90 12   100 1131 8   200 1131
B785 8.14 10   100 785 8   200 785
B503 5.93 8   100 503 8   200 503
B385 4.53 7   100 385 7   200 385
B283 3.73 6   100 283 7   200 283
B196 3.05 5   100 196 7   200 196
                   
Long mesh                  
C785 6.72 10   100 785 6   400 785
C636 5.55 9   100 636 6   400 636
C503 4.34 8   100 503 5   400 503
C385 3.41 7   100 385 5   400 385
C283 2.61 6   100 283 5   400 283
                   
Wrapping mesh                  
D98 1.54 5   200 98 5   200 98
D49 0.77 2.5   100 49 2.5   100 49
                   
Stock sheet size   4.8m x 2.4m = 11.52m2 per sheet        
                   
 
 (Return to Page Top)
 
AVERAGE WEIGHT kg/m3 OF STEELWORK REINFORCEMENT IN CONCRETE
FOR VARIOUS BUILDING SUBSTRUCTURE ELEMENTS
             
Element kg/m3 concrete
   
Pile caps 110 - to - 150
Tie beams 130 - to - 170
Ground beams 230 - to - 330
Bases 125 - to - 180
Footings 100 - to - 150
Retaining walls 150 - to - 210
Rafts   60 - to - 70
Slabs - one way 120 - to - 200
Slabs - two way 110 - to - 220
   
 
(Return to Page Top)
 
Introduction   |   Commercial   |   Domestic   |   Equestrian   |   Environmental   |   Plant Hire   |   Company   |   Links   |   News   |   Contact