Definition of some Concrete related terms in Civil Engineering

Cement: 

cement

This is the bind or matrix that binds rock particles and sand grains together in the presence of water to form a solid concrete mass.

Cementation:

Cementation

The process of injecting cement grout under pressure into cracked rocks to strengthen and make them watertight.

Cement grout:

cement grouting

Fluid slurry for injection into joints of brickwork or masonry.

Concrete:

concrete

A mixture of sand, stone, water  and cement which hardens to a stone like mass. Concrete is used in various civil engineering and building works.

Concrete mixer:

concrete mixer

A machine that mixes cement, sand , water and graded rock particles to form concrete in a fast and efficient manner.

Concrete pile: 

concrete pile

A reinforced concrete precast pile driven into the ground.

Concrete pump:

concrete pump

Pumping machines that can pump concrete at the rate of over 50m³/h to  about 500m away or 50m height.

Concrete testing.

concrete testing

These are standard tests conducted on concrete cubes after 28 days of curing. It is usually done on site to assess the strength of concrete mix.

Concrete spreader

concrete spreader

A road building machine that uniformly spreads concrete or Asphalt poured in front of it.

Cast in place concrete.

concrete cast in place

Concrete structure that is moulded on site and not assembled with precast units.

How to Install a Steel Gate of a House

A gate is an entrance into a fenced building. Gates  can be made of wood or steel. However steel is the more common material used. Steel gates are installed supported by steel or concrete columns or both. Because steel gates are heavy, they usually require strong column support. 

You might have noticed that gates are mostly installed with fat concrete column supports. But it can also be installed with a leaner steel column. However a gate installed with a fat reinforced concrete column can help resist impact damage than that installed with only a steel column.

Steel gates can be installed with readymade columns made of steel or precast column units. It can also be installed with reinforced concrete columns casted Insitu. This article will briefly discuss how a steel gate can be installed with reinforced concrete columns casted Insitu.

How a Steel gate is installed supported by two  concrete columns casted Insitu.

1 The base of the columns is first excavated; it should be at least 300mm deep with length and breadth of at least 1000mm.

Gate installation: based prepared

2. The base reinforcement is inserted as well as the column reinforcement bars which must be truly vertical.

3. Next the prepared mix concrete is poured inside the excavated column base to the required level.

4. After about an hour when the  column base has hardened a little, the gate can be propped in place, making sure that the gate is securely attached to the column reinforcement using the connectors installed with the gate.

5. Next the column formwork is put in place and we’ll propped. Make sure the gate and column formwork is plumb.

Column formwork being put in place

6.  Pour the already mixed concrete into the column formwork.

Concrete poured into column formwork

7. Wait for at least 7 days before removing props and formwork. The gate should be ready for use after 28days of casting.

How many 12mm Reinforcing Steel Rods is supplied per tonne.

reinforcing steel

Note these facts ;

Density of Steel = 7850kg/m³

Density = mass / volume

Volume of steel= πr²L, where r is the cross sectional radius of the steel and L is the length of the steel rod

Reinforcing steel for concrete is sold in lengths of 12m.

1 tonne = 1000kg

1m = 1000mm

Question: How many 12mm  reinforcing steel will be sold to you per tonne.

Calculation:

Cross sectional radius is 12mm /2 = 6mm

Length of steel is 12m, therefore

Volume of steel is πr²L, that is;

3.142×(6/1000)² ×12=  0.001357344m³

Since, Density = mass / volume, it also means that;

Mass = density × volume

That is; 7850kg/m³ ×0.001357344m³

= 10.66kg

Since 1 tonne is 1000kg it implies that 1000kg/ 10.66kg= 93.81 but you will be supplied 93 pieces.

Imposed Loads for Residential Buildings

Floor usageDistributed load (kN/)Concentrated load (kN)
Type 1: self contained dwellings 1.51.4
Type 2: Apartment houses, boarding houses, hotels, residential clubs, block of flats .
Boiler rooms, motor rooms, fan rooms and the like.7.54.5
Communial kitchens, laundries34.5
Dinning, lounges, billiard rooms22.7
Toilet rooms2
Bedroom, dormitories 1.51.8
Corridors, stairs, landings, foor bridges, balconies 34.5
Type 3: Hotels & Motels
Boiler rooms, motor rooms, fan rooms and the like. Including weight of machinery7.54.5
Assembly areas without fixed sitting, dancehall bars 53.6
Assembly areas with fixed sitting4
Corridors, stairs, hallways, landings, footbridges etc44.5
Kitchens, laundries 34.5
Dinning, lounges, billiard rooms22.7
Bedrooms21.8
Toilet rooms2
Balconies4

Brief Introduction to Reinforced Concrete Design

In this article, the following questions will be answered.

  • What is concrete?
  • What is reinforced concrete?
  • Strength of concrete.
  • Concrete mix ratio for reinforced concrete.
  • Types of Steel used for reinforced concrete.
  •  letter codes for reinforcement steel.
  • Code of practice.
  • Structural layout.
  • Prior mathematical knowledge.

What is concrete?

Concrete is produced by the mixture of cement, sand, graded stones and water. It hardens to a solid mass in 28 days.

What is reinforced concrete?

Reinforced concrete is simply concrete structure that has been strengthened with steel.

Strength of concrete ( for reinforced concrete)

The strength  is  concrete that  is the accepted standard for reinforced concrete is 24 kN/mm²

Concrete mix ratio for reinforced concrete 

The standard mix ratio for reinforced concrete is 1:2:4. That is, 1 part of cement to 2 parts of fine aggregates (sand) to 4 parts of coarse aggregates ( graded stones/gravel/granite)

Types of steel used for reinforced concrete.

  1. Mild steel: have strength (fy) of  250 N/mm²
  2. High yield steel: have strength (fy) of 460 N/mm² 

High yield steel is more economical and is mostly used for reinforced concrete design.

Letter codes for reinforcement steel

R for mild steel

Y for high yield steel  (type 1 bars)

T for high yield steel (type 2 bars)

Square twisted high yield bars are type 1 while ribbed bars are type 2.

Code of practice

There are many codes of practice for reinforced concrete however the code used in this article is BS 8110.

BS 8110 is the former British code used for reinforced concrete design.

Every country or region has their own design code or uses adopted code from other countries or regions.

Structural layout

Structural layout is the drawing derived from architectural drawing. It shows  the arrangement of reinforced concrete structural elements such as slabs ,beams and columns and how these elements support the building structure. Structural layout must is done in such a way that it is;

1.Sensible

2.the structural elements are economically arranged.

3. It does not distract or change the original design of the architect except where absolutely necessary and that is after consultation with the architect. 

Prior mathematical knowledge 

You should have learnt how to calculate shear forces and moments of framed structures.

Unit Mass of Building Materials based on BS 648

Asphalt
Roofing 19mm thick42 Kg/m²
Damp-Proofing 19mm thick41 Kg/m²
Road & Footpath 19mm thick44 Kg/m²
Bitumen Roofing Felt
Mineral Surface Bitumen 3.5 Kg/m²
Blockwork
Solid 25mm thick stone aggregate55 Kg/m²
Areated 25mm thick stone aggregate 15 Kg/m²
Board
Blockboard 25mm thick12.5 Kg/m²
Brickwork
Solid clay 25mm thick55 Kg/m²
Solid concrete 25mm thick59 Kg/m²
Cast stone 2250 Kg/m³
Concrete2400 Kg/m³
Flagstones
Concrete 50mm thick120 Kg/m²
Glass fibre
25mm thick slab2 – 5 Kg/m²
Gypsum panels and partitions
Building panels 75mm thick44 Kg/m²
Lead
Sheet 2.5mm thick30 Kg/m²
Linoleum
3 mm thick 6 Kg/m²
Plaster
Gypsum. 13mm thick22 Kg/m²
Plastic sheeting corrugated4.5 Kg/m²
Plywood ( per mm thick)0.7 Kg/m²
Reinforced concrete2400 Kg/m²
Rendering
Cement : sand (1:3) 13 mm thick30 Kg/m²
Screeding
Cement : sand (1:3) 13 mm thick30 Kg/m²
Slate tiles
(Depending upon thickness & source)(24 – 78) Kg/m³
Steel
Solid mild steel 7850 Kg/m³
Corrugated roofing sheets per mm thick10 Kg/m²
Tarmacadam (25 mm thick)60 Kg/m²
Terrazzo (25 mm thick)54 Kg/m²
Tiling / roof
Clay70 Kg/m²
Timber
Softwood590 Kg/m³
Hardwood1250 Kg/m³
Water1000 Kg/m³
Wood wool
Slabs 25mm thick15 Kg/m²

Unit Mass of Building Materials