Engineers – Architects – Design & Construct – Consultants
HOW DOES CLEVA-CRETE IMPROVE CONCRETE STRENGTH?
CLEVA-Crete admixtures enhance low permeability and strength, while adding ductility and thus resultant durability to the life of concrete. ‘CLEVA-Crete’ technology works with the calcium hydroxide and the free water in concrete to produce additional calcium-silicate-hydrate (C-S-H) gel, the nano building block of concrete. This is an exact science, calculated using the proven ‘Powers’ calculation model that works out how much free water there is in your mix design. This permanently disrupts normal capillary formation, leading to ultra-low permeability and superior long-term shrinkage reduction.
CLEVA-Crete does not rob any hydration water in its process, rather it creates a non-hygroscopic, shrinkage and crack reducing concrete. This is mainly due to the fact that the usual osmosis effect on concrete as it is drying, is stopped and the moisture is retained in the slab where it forms nano sized pure C-S-H. The result is a tough, durable, strong C-S-H material that densifies, creating a stronger resultant concrete. There is a typical gain of 13-17% increase in MPa during the setting stage of concrete which is the first couple of days, then as the concrete cures through the 28 day process, strengths show a 4 to 11% increase in MPa overall and overtime.
HOW DOES CLEVA-CRETE AFFECT THE SETTING AND CURING TIME OF THE CONCRETE?
CLEVA-Crete creates and adds more of the right type of calcium silicate hydrate, as it decreases setting times by 13 to 17% on average. It is typical to see 7 to 10 day strengths after 24 to 72 hours from being poured. After approximately 72 hours, there should be no moisture released out of the slab. Full curing time of the concrete usually occurs at the same time as normal, at or soon after 28 days, as with any other concrete or control mixes. At this point there is typically no more than 4 to 11% increase overall after 28 days.
The densifying process of the surface hardness is dependent on weather conditions and humidity. In recent testing, after 28 days of a taber-rotary-abraser test, CLEVA-Crete showed to be a little softer than control, however this all changed after 90 and 120 days. Using the same taber-rotary-abraser test, CLEVA-Crete showed a lot harder and denser than control and all other densifying products tested.
HOW DOES CLEVA-CRETE AFFECT THE CONCRETE SHRINKAGE?
CLEVA-Crete improves shrinking rates by almost 17% better than a typical SRA. CLEVA-Crete grabs free water and turns it into a pure C-S-H gel and as this gel does not evaporate at all, only the very top fractions of a millimetre of the concrete will dry out. This results in a concrete with reduced shrinkage.
HOW DOES CLEVA-CRETE COMPARE WITH CONVENTIONAL CRYSTALLINE GROWTH ADDITIVES?
Crystalline growth, technology initially allows all moisture to enter the concrete matrix via the capillaries. These crystals grow and expand very well. As they do, they slow down the travel speeds of the wicking moisture enough to notice a drying effect, however it is stated in official documents that they will not keep all the moisture out. Issues may be seen with this technology because it needs ingress of moisture to get a re-active swelling of their crystals, lowering the pH of the entire matrix and starting the deleterious process of the steel, which may well result in eventual catastrophic failure. As the crystals form en masse, the excessive product will leach out in the form of an efflorescence that effects the aesthetics of exterior or overhead building or infrastructure elements.
WHICH BUSINESSES HAVE UTILISED CLEVA-CRETE TECHNOLOGY?
Major Construction companies whos’ clients demand an MVRA (Moisture Vapour Reducing Admixture), to control the moisture in flooring issues, or need superior waterproofing for lift-wells, underground car-parks, concrete rooftops, extreme acid/alkaline environments, wineries, sewerage treatment or de-salination plants or docks, utilise this technology.
Our high profile clients include all major ready-mix suppliers to infrastructure, commercial, healthcare, aged care, utilities and residential, we can also confirm that major international social media organisations and on-line shopping companies have used our technology to overcome the serious problem associated with todays demand for fully automated and robotic supply chains. CLEVA-Crete eliminates moisture and dust from emanating from concrete, severely reducing ‘copper and silver creep corrosion’ on printed circuit boards and miniature surface-mounted components at major data control centres and where fully robotic technology is used.
One of the key benefits is that CLEVA-Crete creates the lowest permeability of moisture known to concrete and due to the fact it densifies concrete so effectively, there is no dusting when used in large scale projects including factory floors and precast panels in data centres and automated warehouses.
HOW DOES CLEVA-CRETE AFFECT THE CONCRETE SLUMP AND WORKABILITY?
Both terms relate to viscosity but slump is very different to how workable the concrete becomes.
When an agi truck driver reverses up to the slump stand to verify/correct slump, it is easy to over slump CCMC (Cleva Crete Modified Concrete), due to the amorphous style of C-S-H being formed. Amorphous C-S-H predominantly stacks flat causing concrete to have the appearance of setting up a high slump, but in reality it improves mortar movement and flow.
Correspondingly, as for workability, CLEVA-Crete creates a very workable concrete due to the presence of the C-S-H gel. The noticeable thicker texture when screeding, is deceiving, all finishers are blown away by the ease of bull floating and follow-through helicopter finishing.
CLEVA-Crete cures from the inside out and the cream or gel that is created makes bull floating easy and saves the usual time having to work up a rich cream, or cast water to get a workable finishing material so as to get a very flat top and finish.
Most Grano’s find that they can typically finish an hour or two earlier than normal and get a much flatter resultant surface.
Also most pump operators who have pressure gauges on their equipment including on their lines, note that there is a drop in the hydrostatic pressure in the lines by at least 35% due to the fact that this nano-sized gel, makes the stone roll over easily and the concrete flow smoothly.
There will be no need to work up a finishing cream and you will get the concrete very flat, in less time than normal. You can get a nice hard burnished finish on the concrete just the same and in many cases, on large slabs you can cut the control joints in on the same day as the pour.
ARE STANDARD CURING MEASURES REQUIRED WHEN USING CLEVA-CRETE?
All CLEVA-Crete admixtures are not the same as an AS 3799—1998. liquid membrane-forming curing compound.
When an AS 3799—1998. liquid membrane-forming curing compound is specified for concrete, CLEVA-Crete would recommend that you use one.
Combinations of high temperatures, winds and low humidity would require placement planning that include ‘Hot Weather’ considerations with concrete placement and finishing. Combinations of high temperatures, winds and low humidity could result in challenging conditions with concrete placement and finishing.
On a normal day, the answer to your question is no, however, all standard procedures for pouring in cold weather and for pouring in hot windy weather as advised by Cement Concrete & Aggregates Australia, should be adhered to, this means that many concrete finishers will choose to use a curing agent, or keep the finished concrete wet till sundown, at such times.
The nano-sized particles of calcium silicate hydrate that are produced fill any void in the concrete’s matrix with a resultant dense hard finish that you would ordinarily try to achieve by burnishing the top.
CAN CONCRETE COVER ON STEEL, BE REDUCED WHEN USING CLEVA-CRETE?
Yes, however this is dependent on the size of the aggregate being used in the concrete and whether any steel or synthetic fibres have been used in the matrix, as moisture will travel through absorptive stone and long fibres. Due to the fact that CLEVA-Crete makes the mortar extremely impermeable in concrete precast elements, piers and footings, some stakeholders in the industry are winking at 10 to 12mm cover, especially where side edge lifters are involved in structural elements. In rheology, when using 5 to 7 mm aggregate and no fibres, many involved in cellars, car parks and pools, are reducing steel cover.
The CLEVA-Crete 842 RP variant is specifically designed as a Reo Protection product for many low cover areas in precast or pouring deep foundation piles where the integrity of spacers could be compromised in aggressive environments. While such concrete is in its plastic stage, there is a chemical reaction that takes place, causing the steel to be coated by the Rio Protection chemical and manufacturers expect to double the life expectancy of the steel due to this.
WHAT MAKES CLEVA-CRETE SO SMART?
CLEVA-Crete relies on an exact science, calculated using the proven ‘Powers’ calculation model that works out how much free water there is in your mix design. CLEVA-Crete does not rob any hydration water in its process, rather it creates a non-hygroscopic, shrinkage and crack reducing concrete. This is mainly due to the fact that the usual osmosis effect on concrete as it is drying is stopped and the moisture retained in the slab where it forms nano sized pure C-S-H.
This technology reduces moisture egress so effectively that it is possible to schedule the early installation of VOC free moisture sensitive water-based coatings, adhesives, and resilient flooring products.
HOW DOES CLEVA-CRETE AFFECT THE CONCRETE DESIGN LIFE?
All concrete forensic engineers have very different views on what causes catastrophic failure, yet will all agree that by reducing the permeability of concrete, slowing ingress of chlorides, sulphides, moisture and oxidised or carbonating materials, you will lengthen the life of any project. The more impermeable the concrete, the longer it lasts.
HOW DOES CLEVA-CRETE FARE WITH AN EXTREME CONDITION SUCH AS RADON GAS AFFECTED SITES?
CLEVA-Crete technology has been successfully utilised over radon gas affected substrates all over the world for over 10 years. In fact, the most contaminated radioactive site in the world, the Fukushima Daiichi nuclear power plant, has used CLEVA-Crete technology to completely seal the contaminated site as it is so affective in controlling such hazardous radioactive emissions.