Plain Cement Concrete: The Traditional Art of Making a Construction
The cement concrete with no reinforcement is called plain cement concrete known as Pcc. It is simple mixture of cement, sand and the suitable proportion of water.
It is occasionally called mass cement concrete or cement concrete.
It is very much stronger in compression but fragile in tension and shear.
Things needed of build Plain cement concrete:
? Portland Pozzolana Cement (PPC) is normally used cement in Plain Cement Concrete.
? It should have a suitable degree of fine quality.
Sand (Fine aggregate)
? The using sand should be solid, razor-sharp and angular.
? The size of sand should not be bigger than 5 mm.
? Sand should be liberated from dust, organic particles, etc.
3) Coarse aggregate
? It is simply known as aggregate.
? Using of aggregates should be liberated from dust, foreign materials and also tough to resist adequate stresses.
? Stone ballasts passed through the square sift of 20 mm and retained in the square sift of 5 mm are used as coarse aggregates.
? Aggregates should be well graded so that the voids do not exceed 42%.
? Water use should be free from oils, acids, alkalis, salts and vegetable growths.
? Water having a pH level more than 6 is suitable for use in plain cement concrete.
Plain Cement Concrete Uses
Plain cement concrete is used for:
(1) It is generally used in the building of the column foundation, massive gravity dams, flooring, etc.
(2) Rigid pavement construction also known as reinforcement-less rigid pavement is used by Plain Cement Concrete.
(3) PCC is used in small scale canal construction.
(4) Stone masonry works also use in Plain Cement Concrete.
Plain Cement Concrete (PCC) Properties
Properties of plain cement concrete are:
The PCC should have enormous compressive force. The tensile force should be 8-12% of compressive force and shear force should be 8-10% of compressive force.
Compressive force of the PCC depends upon the following:
i. Cement Content
ii. Water Cement Ratio
iii. Method of mixing, placing, compacting and curing.
iv. Quality of materials used
v. Age of the concrete.
PCC should be able to stand firm climatically as well as chemical actions to be robust.
PCC should be exceedingly feasible. It should be effortless to mix, manage and transport. It should be liberated from bleeding and segregation.
4) Fire Resistance
PCC should be exceedingly resistive towards the fire to thwart problems like firing.
How to construct Plain Cement Concrete (PCC)
Plain Cement Concrete preparation includes the following step:
a) Selection and preparation of ingredients: An assortment of ingredients such as cement, sand, aggregate and water should be cautiously selected and stored separately and properly according to the purpose and strength of concrete desired.
b) Mixing of ingredients: Ingredients of PCC are mixed accurately with their relative part. Mixing may be of two types: Hand mixing and Machine mixing.
c) Transportation and placing: Prepared concrete is transported physically in an iron pan or mechanically through wheelbarrow or by buckets or by the pump. The media used in transportation depends upon the types and nature of the work to deposit the concrete in its required place and position as fast as possible.
d) Concrete Compaction: Removing air bubbles or air voids to make concrete more thick and compressed. The newly placed concrete should be compressed with rollers, rod, and vibrators. This process is known as concrete compaction.
e) Surface Finishing: The important process of PCC is surface finishing .Finishing means the removing of irregularities, voids etc current on the surface. After concreting the rough concrete surface is leveled during the finishing process.
f) Concrete curing:
? Jute bags and clothes are prepared after 2 /3 hours of concrete foundation by wet curing.
? Thumping or spraying curing is prepared for a minimum of 14 days after 24 hours of concrete curing.
What to do or what not to do in PCC Work?
What to do?
1. When PCC work is underground, loose resources from the side of the pits or trenches should be detached.
2. De-watering should be done before PCC work when the water table is elevated.
3. Water should be added to the concrete according to the ratio of water-cement.
4. PCC work should have the same size and thickness in Shuttering.
What not to do?
1. Concrete mixing on bare land should not be done.
2. PCC work with formwork should be allowed.