More information

Waterproofing/hydrophobic properties

The material is capillary breaking and there is no water absorbency at all. Water can penetrate about a millimeter or two where the pores are open. As a test, we had a bit of our light weight concrete lying on the bottom of an aquarium for 15 years, weighed down with a piece of lead. If the piece of lead is removed the material today still rises to the surface. When SENAD® HLWC is pumped into drill holes in foundation works, the material pushes the water in front of it up to the ground until clean SENAD® HLWC emerges. The material can be applied between two layers of concrete which produces a capillary barrier. The material breaks the capillary force because it is hydrophobic.

Density

On site, we can mix the density (strength/weight) we desire. This is controlled by a computerized device available to all blenders. For each mixture we enter the formula for the desired density needed at the moment. We use mixers that mix 135 liters, 250 liters, 1 m³ and 2 m³. An example of the use of different densities can be underground crawl spaces and houses standing on socles (short plinths) etc. Higher density of our concrete can be used around the property when casting the lower joists. Lower density material is then used as filling. The material can be pumped down under concrete floors where there is a gap between the concrete and the aggregate. Usually aggregates sag under a heavily stressed concrete floor or previously poorly performed foundation work. The gaps are afterwards grouted with SENAD® HLWC which absorbs forces and fills the void. You also benefit from the material’s other qualities, such as radon sealing, insulation etc.

Air pore significance

The air pores in the material are controlled. Their size never changes. The amount of bubbles is changed.

During rock grouting air can be compressed. This makes the air pores contract and then expand in larger voids. Air pores are controlled in the mass. The size of the air bubbles never change. It is the amount of air bubbles that varies in the lightweight concrete.

Insulating & Gas proof

SENAD® HLWC lightweight concrete is insulating and airtight and nothing penetrates it. We have used our lightweight concrete to repel oil odors and radon. One example is a daycare center in Östersund, which had to be closed due to too much radon. The daycare center had a crawling space. We filled the space under the system of joists with SENAD® HLWC. Two weeks later the daycare center opened again. The radon gas had then decreased so much that no danger was detected.

Environment

Uppsala has extremely strong environmental standards. There conventional concrete can not be used from more than half a meter to one meter down, without an exemption from environment officials. We submitted samples of SENAD® HLWC to two accredited companies, one in Denmark and another one in Germany. There was no measurable leaching in any of the tests. The tests basically consist of taking a sample when it hardens, grinding it and putting it in a Melitta filter. Then water is added and the amount of surfactants and any other substances that leach are measured.

Because of our material’s good qualities, our product is one of a few that meet these tough standards in Uppsala.

Processing

It is possible to carve in the concrete. This depends on the density we use. The higher the density the more our material acts like ordinary concrete.

Our concrete is very easy to work with after curing. It is possible to saw the material and cut it with a knife or any other tool after curing. SENAD® HLWC has also been used for house building in the Philippines. Where they wanted a window, we used a saw to create a space for the window. The piece we cut out was later used as a kitchen-sink.

stavangergatan-garage-hsbdsc0442

Fire safety and fire protection

One of all tests with SENAD® HLWC was together with the Swedish Civil Contingencies Agency (MSB).

  1. We organized a full-scale test of a so-called flashover container. In two containers we built a model containing an older floor with wood shavings.
  2. The two floor structure was built in the same way except that one was provided with a slab of 50mm SENAD® HLWC directly on top of the wood shavings.
  3. After curing the top of the contents of the container was ignited and a flashover occurred after no more than two minutes.
  4. After about 15 minutes the older floor started collapsing and was completely collapsed after 18 minutes. During the same period, the temperature beneath the slab cast with SENAD® HLWC only increased a few degrees.
  5. The fire continued until the upper material completely burned out and formed a coal bed on the floor.
  6. After two hours a maximum temperature of around 82 degrees Celsius was reached beneath the SENAD® HLWC slab. Inside the concrete the temperature reached 88 degrees after four hours.

The material has been tested by SP Technical Research Institute and received the fire rated to A 120, which is a very good result.

“-Very impressive” was Fire chief Ulf Lundström’s spontaneous comment.

Materials Technology

SENAD® HLWC L (400 – 1000 kg/m³)

SENAD® HLWC L (L=Light) is a technical concrete. It is manufactured by a method patent in special mixers and contains water, cement and a surfactant (Surface Active Agent). In manufacturing SENAD® HLWC L a surfactant is added in the mixing process to obtain a technical-chemical concrete with an air content of approximately 84-60%. The properties of SENAD® HLWC L may vary depending on the quality of aggregates. Pretest should be done with the chosen aggregates to ensure required quality.

Environment

Impact on the environment

SENAD® HLWC has an undetectable impact on the environment as it only contains cement, water, air and detergents.

Environmental policy

Working with the material SENAD® HLWC promotes quality and environmental progress and puts emphasis on the environment during the entire process. It creates opportunities for the global market to use our eco friendly and economically efficient material.

Quality and the environment

Quality and environmental considerations have been and are the cornerstones of our light weight concrete development. Our production thinking and product development is led by a strong environmental awareness. Great importance has been attached to lessen energy consumption and to choose the best environmentally economic alternatives for grouting and and other projects.

The material

SENAD® HLWC can be 100% recycled in an environmentally sound manner. Studies show that there is no degradation of additives that could produce harmful emissions. There are also no reported cases of health effects from the additive.

Radon and Radon Gas Sealing

General information about Radon

Radon is an invisible and odorless radioactive gas that is formed when the radioactive element radium decays. Radon progeny sticks to the dust we breathe and will in this way be inhaled.

Radon concentration is measured in Becquerel per cubic meter of indoor air (Bq/m³). 1 Bq/m³ means that an atom decays per second in each cubic meter of air.

The limit and guideline values available for radon and other naturally occurring noble gases has been established in consultation between the various authorities concerned. Limits, which are binding, are, for example, Building Regulations and Food Administration’s drinking water regulations. Approximate values you’ll find for example in the Board’s general advice on radon in indoor air.

Where does Radon exist

Radon is everywhere – in soil, air and water.

Read more

How do I remove Radon?

If the result shows that there are more than 200 Bq/m³ in indoor air you should sanitize the house. If it is the building material that emits radon, you need to increase the air circulation. In simpler cases, it is often enough to install some type of air system or install ventilators.

  • If the radons comes from the ground it is sufficient in simpler cases to seal the wells for wastewater, insulate around the conduit for water pipes or deep cracks.
  • For stronger measures it is needed to alter the pressure conditions to prevent the air coming  from the ground into the house. For example, this can be done by installing a fan that diverts the ground air (radon extractor) before it enters the building. Sometimes these measures need to be combined.
  • If the radon comes from the water, it is usually sufficient to aerate the water vigorously with a specially designed radon separator.

SENAD® HLWC solution – Radon Sealing

In many cases the above measures are not enough, but greater efforts are required to reduce the radon in the building. The material SENAD®HLWC is a concrete material with a controlled pore system (capillary) which prevents transport through the material. We combine this with a kind of plastic foil that is cast in. We do this to eliminate disintegration by UV radiation and physical impact over the years.

Kindergarten Fåker (Östersund 2011)

The problem

High radon levels during a rebuild. Underground crawl space was fixed with a cast on the ground with only the fiber-reinforced Senad, to reduce cracking.

Result

The measurements from Fåker/Ostersund shows that our material SENAD® HLWC has a good effect when it comes to reducing radon (the invisible and odorless radioactive gas) contained in the building. Approximately 1300 was recorded and afterwards it measured around 200. We are happy with this result. We achieved it not even using an age-resistant air-sealing plastic foil.

Internal testing:

We have done tests with light weight concretes, various cement qualities as well as well considered and tested combinations. Everything indicates that it does not permeate air at one (1) bar pressure. The test is done in the way of putting down a prism (e.g. impactor 150x150mmx300mm) in water. In the specimen there is a hole in which we insert an adapter and through it we then insert air.
The hole in which we have the adapter is cast solid and then we add air at a pressure of one (1) bar. Upon a successful result, it will not emmit air bubbles in the water.

Reference object regarding crack grouting

Sealing around holes for ventilation in floors of the State Department.

Nordea HK (Resolved 2000 Sveavägen Stockholm)

Radon sealing was made in the form of micro-crack-grouting in the concrete floor in the basement. This project we performed as a subcontractor to the NCC. The metro/tube goes beneath Nordea HK, Sveavägen and exhausts and radon were pushed into the building. Measurements were taken before and after the operation, and these showed that neither radiation nor exhaust fumes were longer in the building after our activity.
In places where the ground was pierced, the new sewer openings were filled again with concrete. Also a hose  was placed in the joints between the old and new concrete. These joints were then grouted with SENAD® HLWC so that gas tightness was obtained where otherwise shrinkage cracks occur when the new cast hardens.

Method Description

The measurements from Fåker/Ostersund show that our material SENAD® HLWC has good effect, when it comes to reducing radon (the invisible and odorless radioactive gas) that can be found in the building.
With our method, we use fiber in the concrete to evenly distribute cracks, and apply an appropriate thickness of the concrete material.
The method also means that we supplement the casting of concrete with an age-resistant plastic foil that actively protects against radiation. It also has a long lasting (at least 20 years) resistance to high pH. The concrete protects the foil and is also insulating. The combination of our concrete, fiber reinforcement and plastic film gives a very good protection against radon.

Workflow

  1. Ground is leveled, all protruding material is removed.
  2. A thin protective layer of our material is placed. The thickness should be from 5 to 10 cm to protect the plastic foil against penetration and vermin.
  3. Our material is then coated with a plastic foil. (At the appllication great care is taken not to perforate the plastic foil and splice it correctly.)
  4. Now a layer is cast with our concrete, which is then fiber reinforced on top of the plastic foil. (Thickness should be so abundant that there is a layer that is at least 10 cm on the shallowest place, which also provides extra insulation. The total thicknes indicated in paragraphs 2 and 4 should be 15 20cm.)
  5. Depending on the size of the working area the paragraphs 2, 3 and 4 are done on an ongoing basis plus 1 day for curing.
  6. In this way, a well protected plastic foil inside a cast is obtained, where even the taped joints are protected against UV radiation, drafts or mechanical stress.

History of Cement

The earliest traces of humans use of cement are as early as 3000 BC. Cement was used in Mesopotamia (now Iraq) and later in Egypt. The ancient Macedonians (eg. Time around Philip II of Macedonia and Alexander the Great) began using concrete three hundred years before the Romans, however, the Romans were the first to use concrete on an industrial scale. The knowledge to make good concrete was after the Roman period forgotten. Not until around the 19:th century we managed to make as durable concrete that they used in Roman times.

Today we mostly use a cement called “Portland cement” which is the basis of concrete. Portland cement developed in England in the mid-1700s and was named by its striking similarity to Portland stone, which is a Jurassic limestone on the island of Portland in Dorset, England. Portland cement was patented in 1824.

THIS YEAR’S MATERIAL NEWS ITEM

“Nordbygg gold medal of this year’s hottest material innovation has become an important and appreciated value measure of innovation in the construction sector. Previous winners have experienced the medal as an important recognition that had actual significance of their marketing and sales” said Peter Soderberg, project manager of the North Building and Ecoforum.

Senad HLWC was nominated in 2015 to the Year Material News of the north building. The winner was announced during Nordbygg ecoforum 22 to 23 April 2015 Stockholm Fair “A conference and an exhibition on the future of sustainable urban development”. Here is a link to “Program Ecoforum 2015