We were discussing about exposed aggregate concrete finishing –whisper concrete. Earlier We have learned about how whisper concrete is constructed. Here we will learn about British guidelines to adopt whisper concrete as a most efficient exposed aggregate concrete finishing. We will go to the guidelines directly, as we must finish this topic in this post. We are sorry for inconvenience of reader to break this topic in two parts. The guidelines are:
Under standard conditions-the sub-base should be cement based sub-base. The thickness recommendation is about (150-200) mm.
Over this sub-base a continuously reinforced concrete pavement, known as CRCP, is provided. The recommended thickness of CRCP should be 200 mm. we will discuss about CRCP in upcoming post.
Over the CRCP the whisper concrete is applied. The recommended thickness of whisper concrete is 50mm.
Now guidelines to construct whisper concrete:
1. Generally coarse aggregate of 8 mm size is recommended for this concrete surfacing.
Only 3% oversize of specified size can be accepted.
Only 10% undersize of specified size can be accepted.
2. A limitation on flakiness index is also provided. This should not greater than 25%.
3. Sand used in whisper concrete should be very fine
5. Regarding retarder- there should be glucose, alcohol and water.
6. The spraying surface should be covered with polyethylene sheet.
7. The removal period of polyethylene sheet should be after (8-36) hours.
8. A mechanically rotating bristle stiff brush should be used to remove top concrete mortar
9. The depth of concrete mortar removal should be 1.5 mm