| Cement |
Water |
Aggregate |
| Coarse Aggregate
|
Fine Aggregate |
| 11% |
19% |
33“ |
37“ |
| 70“ |
These proportions will vary depending on the strength of the concrete
being made provided that the total amount of aggregate is not less
than about 70% of the concrete to be made.
| The Outlook for
Recycling Aggregate |
Made from all the chunks of waste concrete produced during
demolition work, recycling aggregate has grown in importance for two
good reasons:
- Given the fact that supplies of natural aggregate are almost
exhausted and a need to protect the natural environment, sources
of natural aggregate of stable quality will become increasingly
difficult to secure from now on.
- The day is fast approaching when vast numbers of concrete buildings,
bridges and highways throughout Japan will have to be upgraded.
With all of the industrial waste disposal plants and factories
already working at full capacity, there is presently no way to
dispose of the enormous quantities of waste concrete generated
if these structures are to be rebuilt.
E&P Recycling Aggregate is produced by pulverizing pieces of waste
concrete into small and/or tiny particles to satisfy certain criteria
such as the shapes and sizes of the resulting particles.
These particles are classified by (1) composition and (2) shape and
size.
(1) Recycling aggregate is separated into two groups according to
the composition of the particles.
One is with small or tiny particles of crushed concrete that are coated
with a mixture of water, cement, sand and/or concrete powder (Fig.
1).
The other group consists of recycling aggregate with particles made
up exclusively of this mixture (Fig. 2).
(2) Recycling aggregate is separated into two general categories and
three strictly defined groups according to the shape and size of the
particles. The two general categories are (a) coarse aggregate and
(b) fine aggregate.
Coarse aggregate itself may be broken down into the two groups which
are referred to as Tamazo particles, and Maruzo particles.
Tamazo
40-20 mm |
Maruzo
20-05 mm |
Kyuzo
05 mm or less |
| Coarse aggregate |
Fine aggregate |
Small or tiny particles of crushed
concrete coated with mixture (Fig. 1),
or mixture only (Fig. 2) |
Mixture only (Fig. 2) |
Note that the Tamazo and Maruzo particles are approximately 40-20
mm and 20-05 mm in size, while the Kyuzo particles are approximately
5 mm or less in size.
Outstanding Features of Rounded E&P Recycling Aggregate
With each particle of E&P Recycling Aggregate having a round
shape and coated with a mortar-like mixture, none have any sharp
corners. This gives E&P Recycling Aggregate the following strengths.
- Sharp decrease in water content:
This is from the smaller surface area from rounded particles,
which allows for significantly decreased water content (approx.
20 L/m3).
- Less generation of materials finer
than 75 _ sieve: E&P's methodology is epoch-making, in that
the quantity of such materials generated by our methods (approx.
5%) is only one fifth of that generated by the conventional methods
(15-25%).
- Lower cost: The production of
high-fluidity concrete is now possible at a lower cost.
| Enhanced E&P Recycling
Aggregate (Patent Pending) |
A drawback to both conventional recycling and E&P Recycling Aggregate
is their high absorption capacity (approx. 10%).
Enhanced E&P Recycling Aggregate (E&P Recycling Aggregate)
has eliminated this weakness by lowering this percentage by an average
of 8 points to 1-3% (1% for coarse aggregate, and 3% for fine aggregate)
with oil allowed to permeate through each particle of the aggregate
(See photos 4-6).
Tamazo
with low absorption capacity (1%) |
Maruzo
with low absorption capacity (1%) |
Kyuzo
with low absorption capacity (3%) |
| Conventional Recycling
Aggregate |
Conventional recycling aggregate can be classified into the following
two categories, each with their own particular strengths and weaknesses.
- Aggregate composed of crushed concrete particles with defined
shapes and sizes:
Strength:
Aggregate production cost is lower.
Comment: It is recognized that the cost of producing
aggregate is lower relative to producing concrete since the larger
specific surface area of each particle increases the ratio of
cement to water. Hence the higher financial burden for producing
concrete.
Weakness
As the fine aggregate contains a large percentage of materials
finer than 75 _ sieve (15-25%), the water content increases greatly.
Comment: The less water used in making concrete, the
better.
- Aggregate composed of natural stone and sand removed from blocks
of waste concrete after being treated with high heat:
Strength:
Since natural stone and sand are used in this recycling aggregate,
there are no issues regarding quality.
Comment: While this may be fine for some circumstances,
this process requires oil burning in a boiler with resulting energy
costs.
Weakness:
A large quantity of materials finer than 75 _ sieve (industrial
waste) is generated during the process of making this aggregate
Comment: This newly generated waste poses serious disposal
problems.
|
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