The Autoclave Advantage
Unlike conventional low pressure block manufacturing, the Autoclave process allows for significantly less cement required in the composition of the block itself which reduces the overall carbon impact in the block manufacturing process and is better for the environment.
New Chemical Structure
Low Moisture Content
Less Volume Change
Lighter in Colour
Stronger and Tougher
The C02 emission from concrete production is directly proportional to the cement content used in the concrete mix; approximately 900kg of C02 are emitted for the fabrication of every tonne of cement produced, accounting for 88% of the emissions associated with the average concrete mix.
Our Autoclave process uses 50% less GUL cement than traditional low pressure cured masonry units. That means that our autoclaved masonry units contain only a 5% cement to aggregate ratio, making them the lowest in the industry. The cement reduction is possible by utilizing a unique mix design that allows for the rapid acceleration of the hydration process under autoclaved conditions. This unique process completely cures the concrete in just an 8 hour process. No more waiting 28 days to meet the CSA 165.04 requirements, our block can be shipped and installed the day after they are manufactured, no more need for lot numbers assuring you of quality cured units delivered to your project every time.
Autoclave masonry units also provide the following advantages:
Units are pre-shrunk in the autoclave and stabilized by high pressure steam curing. Tests conducted over many years by competent testing authorities in Canada and the United States have proved that autoclave curing produces blocks with 50% less shrinkage than units cured by any other known process.
The autoclave curing process completes the curing of concrete within the 8-hour cycle, producing units which will have an initial strength as high as they will ever be. Conventionally cured units may take as long as 12 months to gain their final strength and size. This initial permanent strength is a guarantee to the specifications that quality products will be delivered no matter how short delivery notice is.
LOW MOISTURE CONTENT
Inherent in the process of autoclave curing, units are dried to well below 1% residual moisture content. This reduces later volume change due to loss of moisture to a negligible minimum. The dryness of the block produces improved suction characteristics with mortar and plaster, which results in faster construction of block walls and plastered walls.
LIGHTER IN COLOUR
The high pressure and temperature in an autoclave bleaches the blocks to a very light colour. The exacting control over all parts of the autoclave process is responsible for the high uniformity of colour from cycle to cycle.
NEW CHEMICAL STRUCTURE
With autoclave curing, entirely new chemical reactions take place between cements and aggregates, resulting in more inert chemical compounds being formed. These compounds are relatively unaffected by moisture, further reducing volumetric changes and keeping subsequent shrinkage to a minimum once installed in the service environment.
The lime and salts normally present in Portland cement and aggregates (responsible for leaching and efflorescence of units) become inert under the autoclave process. Those compounds unite with the silicates, added to the concrete mix, to form a new crystalline structure.
LESS VOLUME CHANGE
On the job sites, units are frequently subjected to cycles of wetting and drying during the course of construction. Autoclave cured units have less than 50% volume change versus low pressure cured units during cycles of wetting and drying. This results in better bonding with mortar.
STRONGER AND TOUGHER
Units have a high early modulus of rupture and compressive strength, making them stronger and tougher, more resistant to chipping and breaking in all phases of handling from the manufacturing plant to their final position in a wall.
Design & Process Simplified
The first step in design is the size and shape of block. From there, five basic steps create the Autoclave process: Mixing, Moulding, Pre-Curing, Final Curing, Storage or Delivery. Learn more here!
The cement, silica flour and aggregates are mixed in prescribed amounts with water then fed down to moulding machines.
The hopper feeds this mixture down to the block machines. It is then formed under pressure in the block moulds into wet or green blocks. All cutting, e.g.: scored blocks, or forming is done at this time. These blocks are automatically placed on a steel pallet which are then loaded onto steel racks to be moved into the autoclave for precuring
This stage allows blocks to set properly as hydration occurs making blocks stronger over a 2-3 hour period. This is done inside the plant in an autoclave which is pre-heated to a constant temperate with the autoclave door open, time and temperature are monitored to ensure proper curing.
This stage takes place within an Autoclave, which is 35 m. long and 2.5 m. in diameter. Here, the blocks are put under intensive heat (177 c) and steam pressure (1000 kPa) for approximately 4 – 6 hours. Upon removal from the Autoclave, the blocks are cured and ready of installation.
Storage / Delivery
Following full curing the blocks are then removed and loaded onto a pallet loading machine which evenly stacks the set amount of blocks and then rolls each pallet on to an outdoor shipping area to be picked up by forklift and placed in designated storage areas or placed on flatbed trucks for delivery.