Description
Super-Pozz® is a highly reactive alumino-silicate pozzolan. The product’s
pozzolanic activity ensures increased strength and durability, whilst the unique
particle size distribution and spherical shape makes it the preferred material where
improved workability and/or water reduction is required.
Uses
»High-performance concrete with a low w/c ratio, high early and later age
strength and superior durability are made possible with the inclusion of
Super-Pozz® in the mix
»Super-Pozz® can be used in the production of Self Compacting Concrete (SCC)
»Low w/c ratio Super-Pozz® concrete exhibits decreased permeability, reduced
Sulphate Attack and reduced Alkali Silica Reactivity (ASR)
»Reduced shrinkage. The lubricating action of Super-Pozz® reduces water
content and drying shrinkage
»Excellent cost in use solution for the production of all high strength
Readymix, Precast or Site-batched concretes
Advantages
»Improved rheology with better cohesion, ensures no bleed or segregation
significantly improving the placeability of the concrete
»Pozzolanic properties ie Super-Pozz® has the ability to react with lime,
ensures more efficient hydration and improved strength development over time
»In applications where durability is a key requirement, the dense paste
matrix resulting from Super-Pozz® addition actively decreases permeability
thereby reducing the destructive effects of chloride and sulphate attack
»Super-Pozz® concretes are easily pumped and provide a blemish free surface
finish
Quality Assurance
Micron Materials™
products are manufactured under a Quality Management System which conforms
to the requirements of ISO 9001: 2000. The Quality Management System is
registered and audited by SANS.
Technical Support
Micron Materials™ provides a technical advisory service for on-site assistance
and advice on mix designs, evaluation trials and storage/handling of Super-Pozz®.
Characteristics
Physical
The mean particle diameter of Super-Pozz® typically ranges between 3.9 and 5.0
microns with over 90% of the material having a particle diameter of less than
11 microns. Whilst Silica Fume is finer, it is predominantly single sized.
Super-Pozz®, in relation, with it’s bi-modal distribution effectively fills
the void spaces between fine aggregates and cementitious component creating an
ideal ‘fine filler affect’. This feature is particularly beneficial in high
consistence and Self Compacting Concretes.
Chemical
Super-Pozz® has a similar chemical composition to Portland Cement being made up
of the same basic components but in differing proportions and minerology.
Portland Cement is rich in Lime (CaO) while Super-Pozz® is low. Super-Pozz® is
high in reactive silicates while Portland Cement has smaller amounts.
Typical chemical compounds
The high silica content and sum of the oxides are similar to a Fly ash
designated as BS 3892 Part 1. Through pozzolanic activity, Super-Pozz®
combines with Ca(OH)2(C-S-H) to produce the same
cementitious compounds(CSH) formed by the hydration of Portland Cement.
Hydration reaction
Cement + H2O
= Calcium silicate hydrate (CSH) + Ca(OH)2
Ca(OH)2 + Super-Pozz®
= CSH (additional, durable cement gel)
Typical performance properties
Water reduction
Values obtained for concrete with equal binder content (400kg/m3),
equal HRWR dosage and constant workability
Workability
Though never specified, workability is one of the most critical characteristics
for fresh concrete. Workability refers to the ease of handling, placing and
finishing of the fresh concrete. Approximately 30 litres of water is required
to hydrate 100kg of cement. A normal concrete mix will generally need up to
twice this amount of water, the additional water being required to facilitate
handling and placing. This “water of convenience” not only increases the
water/cement ratio, requiring more cementitious binder to achieve the design
strength, but also increases the possibility of segregation. Super-Pozz®
addition actively reduces the water demand of the concrete mix giving rise to
high strengths and superior cohesion at higher workability levels, without the
requirement for additional water.
Compatibility
With other cementitious materials
and admixtures
Super-Pozz® is suitable for use with all types of Portland Cement and cement
replacement materials eg. GGBS, Fly Ash (Pfa), Micro-silica and Meta-kaolin.
Super-Pozz® is compatible with a wide range of admixtures working particularly
well in high performance concretes when used in conjunction with
superplasticisers.
Applications
Concretes containing Super-Pozz® can be used in virtually any application where
Portland Cement concretes are used. With its unique properties, it is
particularly suited for high performance applications including the manufacture
of proprietary pre-bagged repairs, precision grouts and flowable screeds.
In marine environment concretes, and in any other application where durability
is a fundamental requirement, Super-Pozz® is the preferred addition to the mix.
Recommended uses of
Super-Pozz® Concretes
Addition rates and handling
Typical addition rates of Super-Pozz® in concrete range between 3 - 15% by weight of the cementitious content of the mix.
(For additional rates outside this range, please consult
Micron Materials™ Technical Department) The perceived higher cost of
Super-Pozz® addition can often only be properly evaluated against the dramatic
improvements in long term performance and low maintenance costs. Deciding on
the most suitable Super-Pozz® content depends on a number of factors including
design strength, placing method and durability requirements. To achieve the
optimum benefits of Super-Pozz®, proper curing in line with good concrete ‘practice’ should always be followed.
Super-Pozz® can be handled in terms of batching, mixing and delivery of
concrete in exactly the same way as cement using the same equipment.
In dry powder form, Super-Pozz® can be kept in a storage silo, however it is
often recommended that an aeration system be installed to facilitate easy
discharge from the silo. For advice on Super-Pozz® handling please consult
Micron Materials™ Technical Department.
Mix Design
When using Super-Pozz® in concrete, normal mix design procedures and guidelines
can be used taking into account the unique benefits and properties allowed by its addition.
Fresh Concrete Properties
Performance
Super-Pozz® imparts physical as well as chemical benefits when used in concrete.
In fresh or plastic concrete, the spherical shape and ultra-fine particle size
of Super-Pozz® significantly improves the rheology of the mix. As a result:
»the water content of the concrete can be reduced. As a guide the mix water
should be reduced by a minimum of 10%
»the workability of the concrete is improved at the same water content
without bleeding or segregation of the mix normally associated with highly workable concrete
»pumpability is greatly increased by the use of Super-Pozz®
and it is often possible to pump mixes without altering the fine aggregate
content. In more conventional concretes the coarse aggregate content can be increased eg. at a
Super- Pozz® addition of 15% an increase in stone content of ±5% can be achieved
»Super-Pozz® addition can lead to more cost effective dosage levels of
dispersing admixtures such as superplasticisers.
Hardened Concrete Properties
Strength Development
The typical strength development of concrete containing
Super-Pozz® is illustrated below
As can be seen from the above graph the mix containing Super-Pozz® has comparable strengths to Silica fume concrete at all ages. It also illustrates the continued strength gain up to 90 days due to the pozzolanic properties of Super-Pozz®.
Heat of Hydration
Super-Pozz®, by reducing the water content with a subsequent reduction in the cement
content is very effective in the control of the heat of hydration. At Super-Pozz® addition
levels of between 10-15% reduction in the maximum temperature generated can be in the order
of 15%.
Relative Shrinkage Potential
The largest contributor to shrinkage is water content. Lower water demand Super-Pozz®
concrete can potentially reduce shrinkage by up to 75%.
Water Absorption
The pozzolanic reaction of Super-Pozz®
in concrete produces additional Calcium silicate hydrate gel which fills
pore spaces. This results in a dense paste matrix. The decrease in water
absorption from 28 to 56 days reflects an increase in density as a result
of the refinement of the pore structure.
Durability
Super-Pozz® protects concrete in a number of ways. Hardened Super-Pozz® concrete is less
permeable because Super-Pozz®, unlike other high reactivity pozzolans reduces the amount
of water needed to produce a given slump. Coupled with its high pozzolanic reactivity,
creating more durable Calcium Silicate Hydrate (CSH) gel, Super-Pozz® reduces the rate
of ingress of harmful chlorides and other corrosive salts.
Chloride Ingress
The use of Super-Pozz® as a partial replacement of cement improves permeability thereby
significantly reducing both the diffusion and penetration of chlorides into the concrete.
In addition, research has shown that chemical binding of chlorides is improved by
alumino-silaceous pozzolans. The alumina content of Super-Pozz® exceeds 30%.
Sulphate Resistance
Super-Pozz® addition is an ideal means of providing Sulphate Resistance. Super-Pozz®
decreases the available sulphate thus preventing the formation of ettringite, which could
otherwise form expansive compounds.
Alkali-silica Reaction
Where aggregates cannot be classified as non-reactive,
Super-Pozz® has the ability to react with alkali hydroxides in Portland cement paste making
them unavailable for reaction with these aggregates thereby combating this expansive reaction.
Packaging
Super-Pozz® is available in Bulk (pressurised bulk powder tanker by road), 1-ton IBC’s or
Jumbo bags with plastic inner liner. The product is also available in 25kg plastic lined,
repulpable paper bags. Samples can be obtained from Micron Materials™
on request in buckets.
Storage
Super-Pozz® when stored correctly has an indefinite shelf life. Like cement,
Super-Pozz® must be protected from contamination and moisture. The product can be stored
in bulk in a clean, dry storage silo. Advice on aeration, which may be required due to the
product’s extreme fineness and rounded shape, is available from Micron Materials™ on request.
Health and Safety
Extensive testing has shown Super-Pozz® to be non-toxic and environmentally benign.
No known significant health risks are associated with Super-Pozz® but high concentrations
of dust may cause irritation. It is recommended that suitable protective clothing, gloves
and eye/face protection is worn. In case of contact with eyes, rinse immediately with
plenty of clean water and seek medical advice. For further details please consult the
Material Safety Data Sheet (MSDS) for Super-Pozz®.
Important Notice: Micron Materials™ products are guaranteed against defective materials and manufacture and are sold subject to its standard Conditions for the Supply of Goods and Service, copies of which may be obtained on request. Whilst Micron Materials™ endeavours to ensure that any advice, recommendation, specification or information is accurate and correct, it cannot, because it has no direct or continuous control over where or how its products are applied, accept any liability either directly or indirectly arising from the use of its products, whether or not in accordance with any advice, specification, recommendation or information given.
PLEASE
NOTE:
The following information has been obtained from test results in an
accredited laboratory. Although the information is accurate, variation
in specific parameters might occur from time to time. No guarantee is
therefore given or implied and Micron MaterialsTM
disclaims any liability from damage or consequential loss.