| Lightweight blocks
are manufactured from pumice aggregates and cement with particular
attention being given to their load bearing, thermal and
dimensional properties.
Two classes of block are
available, a Standard textured unit with an irregular
finish and a Colinwell 'Fairlite' unit with smoother finish
for direct decoration.
The usual colour of the blocks is
light grey.
|
Availability |
| Blocks are produced
in a full range of sizes and forms and the table below indicates
the basic sizes available. |
Approval |
| Blocks comply with
BS6073, Part 1: 1981 (Precast Masonry Units). |
Technical Specification |
A. APPLICATION
Standard blocks are intended for general construction both
above and below d.p.c. They have, however, no particular claim to
provide good surface texture and arrises, but Colinwell 'Fairlite*
blocks, provide an attractive finish, particularly if built
fair or painted. |
B. FORM
Blocks are produced in a variety of sizes and in three basic
formats.
1. Solid blocks, which have no formed voids.
2. Cellular blocks, have formed voids which are effectively sealed
at the base of the block.
3. Hollow blocks, have cores which fully penetrate through the
block |
C. BLOCK SPECIALS
A limited range of reveal and closer blocks are produced, but
other specials are available depending on demand and quantities. |
D. SIZE AND WEIGHT
The average block weights are given below. Our Sales Office can
supply the relevant information on availability.
This table indicates the approximate weight (kg) of each block. |
 |
E. DENSITY
Solid, approx. 1100 kg/m³ Cellular, approx. 850 kg/m³ Hollow,
approx. 700 kg/m³
These densities are measured in
accordance with BS6073 and hence results for hollow and cellular
blocks are dependent on core dimensions.
|
F. STRENGTH
Solid, 5.5N/mm³
Cellular, 5.5N/mm³ Minimum Average ]- Minimum Average
Hollow, 5.5NImm³
Higher strengths, up to 7N/mm² are available on request.
|
G. DRYING SHRINKAGE
Approx. 0.035%. |
Durability |
A. USE BELOW D.P.C.
All lightweight blocks with strengths of 7N/mm² are suitable for
use below the d.p.c. while 5.5N/mm² are suitable on the inner
leaf of cavity walls and partitions. |
B. PERFORMANCE IN FIRE
All blocks are manufactured using a Class 1 aggregate.
Comprehensive details on the performance in fire are given in our
Technical Bulletin. |
Acoustic Performance |
A. SOUND REDUCTION
INDEX
The average SRI for plastered leaf partitions, when calculated
over a frequency range of 100-3150Hz gives results between 40 and
46dB dependent on the block type and thickness. Further details
are given in the table below.
|
 |
B. PRACTICAL APPLICATIONS
Lightweight blocks can give adequate sound reduction in party and
separating walls, but to ensure optimum performance we recommend
the use of dense blocks in these situations. |
Thermal Performance |
A. THERMAL
CONDUCTIVITY
The 'K' () value of the concrete is
0.21 W/mK @ 3% moisture content
0.26 W/mK @ 5% moisture content
These standard values are derived
from the CIBS Guide, 1980.
|
B. THERMAL RESISTANCE
The equivalent resistances of lightweight blocks given below have
been calculated in accordance with the procedure laid down in the
CIBS Guide, 1980. |
 |
C. THERMAL RESISTANCE
'U' value (W/m²K)
The following results have been
calculated from the resistance values quoted in section B.
These have been based on a wall
construction consisting of an outer leaf (brick or block), 10Omm
cavity, 10Omm solid lightweight block plastered with lightweight
plaster.
|
 |
 |
Delivery & handling methods |
| Customers should
consider site handling before confirming an order.
1. Crane off loaded packs of
approximately 8m³(10Omm block). The weight of each pack is
approximately 1.0 tonne but our Sales Office can provide more
specific information.
2. Crane offloaded packs can be
strapped to pallets for FLT handling on site. Shrink wrapping is
available at extra cost.
|
Site Information |
A. STORAGE
Where possible blocks should be stored clear of the ground and
protected against snow and rain. Incomplete work should be
covered.
B. LAYING, CUTTING, CHASING AND FIXING
Full guidance is contained in the Colinwell Technical Bulletin.
C. PLASTERING
Wet and Dry backgrounds - Carlite Browning plaster.
D. RENDERING
On lightweight blocks the mix should be between
1:1½:4½ and 1:1:6 or equivalent, dependent on exposure and
render type. in all cases rendering should be carried out to the
thickness and recommendations given in BS5262 : 1976.
E. MORTAR MIXES
A 1:1:6 mix or equivalent is recommended for normal use above and
below ground level.
|
How to Specify |
Specifications should
read as follows.
Colinwell Pumice lightweight blocks to be (size and form) of
(strength N/mm²) with a Standard or 'Fairlite' finish, produced
and supplied by Colinwell Architectural Masonry, built in Standard
cement, lime sand mortar (1:1:6) pole pointed joints as work
proceeds. |
Colinwell Products are subject to continuous
development and the Company reserves the right to alter or change
the specification subject to it continuing to comply with
appropriate British Standard. |
