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1. Ready Mixed Concrete
Ready mixed concrete is designed to enable the user to cast the plastic
material into the required shape prior to hardening.
2. Physical and Chemical Characteristics
Ready mixed concrete is a mixture of:
(i) A cementitious material. (This may be a cement or a mixture of
cement with pulverised fuel ash or ground granulated blast furnace
slag).
(ii) Fine and coarse aggregate.
(iii) Water.
(iv) Admixtures may be added to improve the properties of the fresh
and hardened concrete. The resultant mixture is abrasive and alkaline.
3. Main Hazards
Contact with wet cement mixes such as concrete can cause skin diseases.
Irritant contact ermatitis is caused by the combination of wetness,
alkalinity and abrasiveness
of the cement mixture.
Allergic contact dermatitis may be caused by individual sensitivity
to chromium compounds which may occur in cement.
Cement burns, a form of skin ulceration, may result from contact
with freshly mixed concrete.
4. Precautions
Direct skin contact with wet concrete should be
avoided.
It is also important not to kneel or sit on the wet material
as harmful contact can occur through saturated clothing.
Protective clothing should be worn when handling wet cement,
particularly on the arms, hands, legs and feet e g long- sleeved
clothing, gloves
with full length
trousers, impervious boots.
5. Emergency Action
Where skin contact occurs with wet cement, either directly or
through saturated clothing, the wet cement must be washed
off immediately.
Where eye contact occurs the area must be immediately and
thoroughly irrigated with water.
In all cases of doubt, or where symptoms persist, medical
advice should be obtained.
6. Transportation and Waste Disposal
The carriage of concrete is not subject to hazardous substance
conveyance regulations and vehicle labelling is
not required. In the event of spillage, entry of material
to water courses should be avoided.
7.
Storage
The hardening of concrete can be delayed, extending the period during which
the precautions given above should continue to be taken and during which access
by unauthorised persons should be prevented.
8. Hardened Concrete
Hazard: The surface treatment and cutting of hardened concrete can create dust
which may contain quartz. If inhaled in excessive quantities over extended
periods respirable dust containing quartz can constitute a long term health
hazard.
Precaution: Inhalation of concrete dust should be avoided. Protective Clothing:
Respiratory protective equipment should be worn during the surface treatment
or cutting of hardened concrete where dust is generated. Waste Disposal: Unused
hardened concrete is inert but it should be disposed of in accordance with
local legal requirements.
Caution: Concrete can be harmful if in contact with skin, always wear protective clothing.
Personal Protective Equipment (PPE)
•
Respiratory protection – suitable respiratory protection should
be
worn to ensure that personal exposure is minimal.
•
Hand & skin protection – protective clothing should be
worn
that ensures that cement or any cement/ water mixture e.g.
concrete or mortar does not come into contact with the skin.
•
Eye protection – dust proof goggles should be worn wherever
there is a risk of cement powder or any cement/ water mixture
entering the eye.
•
Foot protection – suitable protection such as steel toe capped
boots should be worn at all times when handling concrete.
•
Hearing protection – suitable hearing protection should be
worn
when cutting concrete using percussive drills etc.