Pervious Concrete

Hydromedia®is an ideal solution for surface

and stormwater management

Hydromedia is a next generation pervious concrete that is also called permeable concrete, porous concrete, no-fines concrete or gap graded concrete.  Carefully controlled amounts of water, cement, fly ash and admixtures combine to form a thick paste around the aggregate particles while eliminating all, or most of, the sand, creating a substantial void content.  Typically, 15% to 25% voids are achieved, allowing a high flow rate of water through the concrete.

Traditional pervious concrete mixtures are placed with compaction being an important component of installation.  Hydromedia’ s advanced design eliminates the need for compaction beyond the initial placement sing a roller screed.  This can eliminate many of the issues of over or under compaction that cause traditional pervious concrete failures.

The most common use for pervious concrete is in pavement in parking lots for use of storm water runoff management.  By capturing water and allowing it to seep into the ground, pervious concrete recharges ground water, reduces runoff, and meets U.S. Environmental Protection Agency storm water regulations. This pavement technology creates more efficient land use by eliminating the need for retention ponds, swales, and other water management devices

Applications

o Commercial and residential parking lots
o Pavements, bike and pedestrian pathways
o Patios
o Swimming pool decks
o Alleyways
o Driveways
o Pavement edge drains and gutters

Advantages of Hydromedia®

o Can form part of a cost-effective Sustainable Urban Drainage System (SUDS)
o Can eliminate the need for detention ponds
o Offers space saving for more efficient land development
o Mitigates surface pollutants
o A more robust wearing surface
o Faster draining
o Smooth, clean look
o Ease of placement due to higher fluidity
o Low compaction requirements

Technical features

o Unit weight is up to 30% less than conventional concrete
o Workable for up to 90 minutes
o Flexural strength of 200-400 psi
o Slump approximately 6 inches
o Void content: Minimum 20%
o Permeability: 4 to 60 gal/min/ft²
o Typical nominal maximum aggregate size: 0.5in (may vary according to regional

Safety features

Reduces glare from wet pavements
Eliminates water accumulation from heavy rain

Safety precautions

The standard rules for good concrete practice and placing must be strictly
observed. The use of safety goggles, hard hat, ear defenders and gloves is
recommended when placing concrete.

First Aid

Eyes: Immediately flush eyes, including under lids, with water for at least 15 minutes to remove all particles. If necessary, seek medical advice.

Skin: Wash skin with cold water and a pH neutral soap as soon as possible, except where open wounds are visible. Attention should be paid to wounds and fresh scars which should be covered with protective paraffin gauze. Seek medical help in cases of prolonged contact with wet concrete.

Ingestion: Rinse mouth with clean water. If swallowing has occurred, drink plenty of milk or water. Do not induce vomiting. Seek medical attention immediately.

Inhalation: Move to fresh air. If symptoms persist, seek medical attention.

Design

There are two factors that determine pavement system design thickness:

1. Hydraulic properties such as permeability (related to yearly average rainfall) and volume voids (related to water storage)

2. Structural properties such as flexural strength offering better loadbearing properties Selection of appropriate Hydromedia® properties is dependent on the more dominant between:

o Hydrological requirements

o Load-bearing requirements

The value of higher importance to the owner/designer governs design thickness.

Subgrade and Subbase Preparation

o Uniform (level) subgrade support

o Compact subgrade to 90-95% of theoretical density

o Increasing compaction decreases permeability

o Stable subbase required, crushed aggregates recommended

o Before starting a project, consult a geotechnical engineer for more information

Delivery

o Retention of concrete workability is 90 minutes

o Rapid drying conditions require special handling and curing

o Concrete can be placed either by chute or conveyor, not by pump

RECOMMENDATIONS

Placement
o Use conventional forms
o Placement should be continuous and rapid
o Can be placed using a paver machine; recommended pavers are available upon request
o Avoid overworking the concrete, especially after striking off and finishing
o Use recommended placement method

Striking off
o Vibrating screeds or standard screeds and roller compacters can be used for strike off
o Riser strips are not recommended due to minimal compaction that occurs with Hydromedia®
o Do not over vibrate or work the top surface

Compaction and finishing
o Compact to height of form with steel roller compactors, vibrating plates or pavers
o Hand tamp near edges and other places not reached
o Complete compaction within 15 minutes of placement
o Minimize overworking or movement of the surface after compaction, including walking on the surface

Jointing
o It is recommended to place joints immediately after compaction; otherwise saw cuts are possible after 7 days of curing
o Contact your local technical representative for further information

Curing and Protection
o Fog mist the surface within 20 minutes of compaction
o Cover with thin plastic sheeting within 20 minutes after placement and leave in place for 7 days.
o Contact your local representative for more information

Maintenance
o Minimal maintenance required (refer to NRMCA guidelines)
o Design site to minimize the flow of soil and leaves to pavement
o Vacuum annually or when clogging test indicates the necessity; alternatively try pressure washing

Hydromedia® is a registered trademark of Lafarge S.A.
Consumers Concrete is an authorized distributor of Hydromedia®.

Disclaimer – The information contained is based upon knowledge and experience of the materials used in the manufacture of the products. However, since the application of the products is carried out by the customer and is beyond the control of Consumers Concrete, there will be no liability or responsibility accepted for any loss, damage or inquiry resulting from the use of the products outside the proper scope and precautions.