GUYANA STANDARD
Section 8- Concrete and Block
Masonry
 Scope
 Reinforced Concrete Practice
 Concrete Quality
 Production of Concrete
 Protection for Reinforcement

SCOPE
This code specifies the requirements for concrete and
block masonry used in structures or buildings.
Reinforced Concrete Practice
 deals with materials such as Cement, stone,
aggregates, water and metal reinforcement
 Cement, aggregates and metal reinforcement shall
confirm to the Specifications given by the ASTM or the
British Standard Institution.
 The maximum size of coarse aggregates shall not be
larger than:
- 1/5 the narrowest dimensions between the
sides of forms
Reinforced Concrete Practice cont’d
- 1/3 the depth of slabs
- ¾ the maximum clear spacing between
individual reinforcing bars or bundles of bars
 Water shall be clean and free from oils, acids, salts,
alkalis, organic materials or other detrimental
substances to concrete or reinforcement.
Concrete Quality
 Based on the design requirements of a particular
structure, the engineer or architect would specify the
quality required.
Concrete Grade
Characteristic
Strength (N/mm2) Category
10
15
10
15
20
25
20
25
Reinforced concrete with
lightweight aggregate
Reinforced concrete
with dense aggregate
Production of Concrete
1. Handling, batching and mixing shall conform to
ASTM C 94
The processes for conveying, depositing and curing is
also outlined in the standard
.
Formwork and Embedded Pipes
In the design of formwork, the following factors should be considered:
- rate and method of placing concrete
- construction loads
- special form requirements for construction of shells, domes, architectural concrete or similar types
of elements.

Conduits and Pipes Embedded in Concrete
Conduits, pipes and sleeves of any material not harmful to concrete may be embedded in concrete with
the approval of the Engineer.
Conduits and pipes of aluminium shall not be embedded in concrete unless effectively coated or
covered to prevent aluminium-concrete reaction or electrolytic action between aluminium and steel.
Protection for Reinforcement
The following minimum concrete cover shall be
provided for reinforcement:
Minimum Cover, mm
(i) Concrete cast against and
permanently exposed to earth
70
(ii) Concrete exposed to earth or weather
- No. 20 to No. 55 bars
- No. 15,
50
40
Protection for Reinforcement - cont’d

Minimum Cover, mm
 (iii) Concrete not exposed to weather
or in contact with ground
(a) slabs, walls, joists
- No. 45 and No. 55
40
- No. 35 bar or smaller
20
(b) Beams, columns
- primary reinforcement,
ties, stirrups
40
Block Masonry
 Sizes
The nominal sizes for Concrete blocks are:
 400 mm long x 200 mm high with a tolerance of + or – 3 mm in
both dimensions
 Standard thickness shall be 100mm, or 150 mm
 Blocks shall be of two hole pattern, and shall have a net cross
sectional area not less than 50% nor greater than 60% of the
gross cross sectional area. The thickness of the face, shell and
web shall be 35 mm
 Certification
Applications for permission to construct block masonry
structures shall be accompanied by a certificate from an engineer
or architect.
Block Masonry
Testing
 When tested in accordance with ASTM C 140, the
Grade A blocks the maximum absorption of water
shall not exceed 208 kg/cu m of normal weight.
 Test for compression strength of blocks shall be made
at 28 days, and a test shall be carried out for each 5000
blocks, each test consisting of 5 blocks.
Block Masonry
Mortar for Blockwork
The mix proportion for mortar shall be 1 part cement:
3 parts sand to achieve a strength at 28 days of 10
N/mm2