About Concrete

• History …

  

  Timeline of the Development of Concrete

  Cement has been around for at least 12 million years. When the earth itself was undergoing intense geologic changes natural, cement was being created. It was this natural cement that humans first put to use. Eventually, they discovered how to make cement from other materials.  

  Concrete and the technology surrounding it has come a long way since its discovery and development. From the great Pyramids at Giza to smart sensors for testing concrete temperature, maturity, etc.

   

  12,000,000 BC
  Reactions between limestone and oil shale during spontaneous combustion occurred in Israel to form a natural deposit of cement compounds. The deposits were characterized by Israeli geologists in the 1960’s and 70’s.
  
  3000 BC
  Egyptians used mud mixed with straw to bind dried bricks. They also used gypsum mortars and mortars of lime in the pyramids. Chinese used cement like materials to hold bamboo together in their boats and in the Great Wall.
  
  800 BC
  Greeks, Crete & Cyprus used lime mortars which were much harder than later Roman mortars. The Nabataeans possibly made waterproof cisterns in the Arabian deserts during this time.
  
  300 BC
  Babylonians & as Syrians used bitumen to bind stones and bricks.
  
  300 BC
  Nabataeans undoubtedly built countless cisterns with waterproof cement by this date in Arabia. Many of these cisterns are still intact and continue to be used today.
  
  200 BC - 476 AD
  Romans used pozzolana cement from Pozzuoli, Italy near Mt. Vesuvius to build the Appian Way, Roman baths, the Coliseum and Pantheon in Rome, and the Pont du Gard aqueduct in south France. They used lime as a cementitious material. Pliny reported a mortar mixture of 1 part lime to 4 parts sand. Vitruvius reported a 2 parts pozzolana to 1 part lime. Animal fat, milk, and blood were used as admixtures (substances added to cement to increase the properties.) These structures still exist today.
  
  500 - 1500 The Middle Ages
  The quality of cementing materials in europe deteriorated. The use of burning lime and pozzolan (admixture) was lost, but reintroduced in the 1300’s.
  
  1678
  Joseph Moxon wrote about a hidden fire in heated lime that appears upon the addition of water.
  
  1779
  Bry Higgins was issued a patent for hydraulic cement (stucco) for exterior plastering use.
  
  1780
  Bry Higgins published “Experiments and Observations Made With the View of Improving the Art of Composing and Applying Calcereous Cements and of Preparing Quicklime.”
  
  1793
  John Smeaton found that the calcination of limestone containing clay gave a lime which hardened under water (hydraulic lime). He used hydraulic lime to rebuild Eddystone Lighthouse in Cornwall, England which he had been commissioned to build in 1756, but had to first invent a material that would not be affected by water. He wrote a book about his work.
  
  1796
  James Parker from England patented a natural hydraulic cement by calcining nodules of impure limestone containing clay, called Parker’s Cement or Roman Cement.
  
  1802
  In France, a similar Roman Cement process was used.
  
  1810
  Edgar Dobbs received a patent for hydraulic mortars, stucco, and plaster, although they were of poor quality due to lack of kiln precautions.
  
  1812 -1813
  Louis Vicat of France prepared artificial hydraulic lime by calcining synthetic mixtures of limestone and clay.
  
  1818
  Maurice St. Leger was issued patents for hydraulic cement. Natural Cement was produced in the USA. Natural cement is limestone that naturally has the appropriate amounts of clay to make the same type of concrete as John Smeaton discovered.
  
  1820 - 1821
  John Tickell and Abraham Chambers were issued more hydraulic cement patents.
  
  1822
  James Frost of England prepared artificial hydraulic lime like Vicat’s and called it British Cement.
  
  1824
  Joseph Aspdin of England invented portland cement by burning finely ground chalk with finely divided clay in a lime kiln until carbon dioxide was driven off. The sintered product was then ground and he called it portland cement named after the high quality building stones quarried at Portland, England.
  
  1828
  I. K. Brunel is credited with the first engineering application of portland cement, which was used to fill a breach in the Thames Tunnel.
  
  1830
  The first production of lime and hydraulic cement took place in Canada.
  
  1836
  The first systematic tests of tensile and compressive strength took place in Germany.
  
  1843
  J. M. Mauder, Son & Co. were licensed to produce patented portland cement.
  
  1845
  Isaac Johnson claims to have burned the raw materials of portland cement to clinkering temperatures.
  
  1849
  Pettenkofer & Fuches performed the first accurate chemical analysis of portland cement**.**
  
  1860
  The beginning of the era of portland cements of modern composition.
  
  1862
  Blake Stonebreaker of England introduced the jaw breakers to crush clinkers.
  
  1867
  Joseph Monier of France reinforced William Wand’s (USA) flowerpots with wire ushering in the idea of iron reinforcing bars (re-bar).
  
  1871
  David Saylor was issued the first American patent for portland cement. He showed the importance of true clinkering.
  
  1880
  J. Grant of England show the importance of using the hardest and densest portions of the clinker. Key ingredients were being chemically analyzed.
  
  1886
  The first rotary kiln was introduced in England to replace the vertical shaft kilns.
  
  1887
  Henri Le Chatelier of France established oxide ratios to prepare the proper amount of lime to produce portland cement. He named the components: Alite (tricalcium silicate), Belite (dicalcium silicate), and Celite tetracalcium aluminoferrite). He proposed that hardening is caused by the formation of crystalline products of the reaction between cement and water.
  
  1889
  The first concrete reinforced bridge is built.
  
  1890
  The addition of gypsum when grinding clinker to act as a retardant to the setting of concrete was introduced in the USA. Vertical shaft kilns were replaced with rotary kilns and ball mills were used for grinding cement.
  
  1891
  George Bartholomew placed the first concrete street in the USA in Bellefontaine, OH which still exists today.
  
  1893
  William Michaelis claimed that hydrated metasilicates form a gelatinous mass (gel) that dehydrates over time to harden.
  
  1900
  Basic cement tests were standardized.
  
  1903
  The first concrete high rise was built in Cincinnati, OH.
  
  1908
  Thomas Edison built cheap, cozy concrete houses in Union, NJ.
  
  1909
  Thomas Edison was issued a patent for rotary kilns.
  
  1929
  Dr. Linus Pauling of the USA formulated a set of principles for the structures of complex silicates.
  
  1930
  Air entraining agents were introduced to improve concrete’s resistance to freeze/thaw damage.
  
  1936
  The first major concrete dams, Hoover Dam and Grand Coulee Dam, were built. They still exist today!
  
  1967
  First concrete domed sport structure, the Assembly Hall, was constructed at The University of Illinois, at Urbana-Champaign.
  
  1970’s
  Fiber reinforcement in concrete was introduced.
  
  1975
  CN Tower in Toronto, Canada, the tallest slip-form building, was constructed. Water Tower Place in Chicago, Illinois, the tallest building was constructed.
  
  1980’s
  Superplasticizers were introduced as admixtures.
  
  1985
  Silica fume was introduced as a pozzolanic additive. The “highest strength” concrete was used in building the Union Plaza constructed in Seattle, Washington.
  
  1992
  The tallest reinforced concrete building in the world was constructed at 311 S. Wacker Dr., Chicago, Illinois.

• Raw Materials …

  

  We are using only highest quality of ingredients in our projects

   

  Water

  Pure drinking water

   

  Binder

  Only freshest cement of different types and strength is used depending on application.

   

  Cement types
  

  Type I	Normal Portland Cement
  	Grey or White
  Type II	Moderate Sulfate Resistance
  	Used for structures in water or soil containing moderate amounts of sulfate
  Type II (MH)	Moderate Heat of Hydration and Moderate Sulfate Resistance
  	Used when heat build-up is a concern
  Type III	High Early Strength
  	Used when high strength are desired at very early periods
  Type IV	Low Heat Hydration
  	Used where the amount and rate of heat generation must be kept to a minimum
  Type V	High Sulfate Resistance
  	Used where the water or soil is high in alkali

  
  Blended hydraulic cements:

  Type IL	Portland-Limestone Cement
  Type IS	Portland-Slag Cement
  Type IP	Portland-Pozzolana Cement
  Type IT	Ternary Blended Cement
  CSA	Cement high in Calcium Aluminum Sulfate Crystals
  	When used with Portland cement concrete, CSA generates a strong cementitious matrix that enhances the physical and chemical properties of the mix

  
  Other typws of cements:

  Rapid hardening Portland cement

  Extra rapid hardening cement

  Hydrophobic Portland cement

  Quick setting Cement

  High alumina cement

  Supersulphated cement

  Water-proof cement

  Expansive cement

  Air-entraining Portland cement

   

  Aggregate

  Besides the common sand and pure quartz aggregate we use the newest types of aggregates such as expanded glass and synthetic beads for making concrete extremely lightweight if needed and at the same time hard and resistant to moisture.

   

  Certain projects require composite structures where mixing concrete with wood, metal or other materials, either as inlays or as structural parts, gives us the possibility to achieve a wide range of desired properties, from heat conducting, magnetic, lightweight to decorative, flexible and randomly generated.

   

  Reinforcements

  Synthesis uses the best available materials for different applications. Options used are micro or macro reinforcement AR glass fibers, PVA fibers, Carbon-fiber meshes, stainless mesh reinforcement, or top quality reinforcement bars cut and bent to precision.

   

  Additives and mixes

  Various additives give additional properties to concrete such as additional strength in optimization of cure process, water impenetrability different mixing and applying properties, and different tactile feel of surface.

   

  Pigments

  We have at our disposal an array of pigments that can satisfy every aesthetic and functional requirement.

   

  And as concrete is such a versatile material, it can be adapted to your specific needs in every detail.

• Types of Concrete…

  During the last two decades, concrete technology has been undergoing rapid developments. In recent years, different concepts of concrete mixes have gained popularity and are steadily progressing from laboratory to the field of practice. 
A wide range of mix designs and add-ins produce concrete with different properties. 


  In our projects we use different types of concrete but mostly we use our Special UHPC Fiber-Reinforced (AR Glass and Carbon) Mix that has exceptional mechanical performance, in particular its tensile strength, resistance to compression and bending, its creep and shrinkage behavior, its fire-resistance, and its water impermeability unlike conventional concrete.
  
It achieves this engineering feature by progressively absorbing the energy applied and efficiently dispersing it throughout the matrix.
  These mechanical properties make it possible to create very slender structures with little or no passive steel reinforcement. 


  By adjusting a mix design we can control flow from none to completely self-consolidating.
  It has micro-fine aggregates that make it extremely dense with less porosity, offering resistance to scratching and staining.
  This super fine design matrix also produces a surface capable of intricate detail with unlimited surface textures, finishes and colors.

  

We have designed and programmed our own Concrete Mix Design Calculator with all the ingredients and parameters input, and we are able to easily make tailor-made concrete mix in just a few steps. 

  
We are working with, researching and experimenting with all kinds of concrete variations, some of them are: 

  
  Regular Conventional Concrete
  Mix of hydraulic cement, natural aggregate and water.
  
  SCC - Self-Compacting / Self-leveling / Self-placing
  Concrete is an extremely fluid mix with the following distinctive practical features.
  
  HPC - High Performance Concrete
  Concrete with strength and durability significantly beyond those obtained by normal means. HPC mixtures are composed of essentially the same materials as conventional concrete mixtures, but the proportions are designed, or engineered, to provide the strength and durability.
  
  UHPC - Ultra-High Performance Concrete
  It s a new class of concrete with exceptional properties of strength and durability. This innovative material produces concrete elements that are up to 10 times stronger than conventional concrete. The UHPC possesses unprecedented flexural strength, allowing for finer, thinner, lighter and more elegant designs. The chemistry is cutting edge while still embracing the natural qualities of concrete.
  
  FRC - Fiber-Reinforced Concrete
  Concrete containing fibrous material which increases its structural integrity (AR glass, polypropylene, aramid and carbon fibers).
  
  UHPFRC - Ultra High-Performance Fiber-Reinforced Concrete
  Owing to a densely packed structure, its compressive strength exceeding 150 MPa, tensile strength is higher than 7-8 MPa. W/B ratio for it is lower than 0.25, it has high content of binder, fibres to ensure a ductile behavior. Use of a quite large amount of super-plasticizers in order to obtain an acceptable work-ability is also a characteristic of the UHPFRC.
  
  PMC / PPCC - Polymer-Modified Concrete
  Developed by adding a polymer material to Portland-cement concrete with the interest of enhancing the fresh and hardened concrete properties (extensibility and tensile strength, impact resistance, abrasion resistance, durability and resistance to aggressive fluids, bond strength).
  
  Polymer Concrete
  Concrete that uses a polymer binder in place of Portland cement (Epoxy, Polyurethane, Polyester).
  
  Terrazzo
  Concrete with visible natural stone or artificial aggregate (washed or ground).
  
  Thin Shell Concrete
  Extremely thin concrete forms of special concrete mix and application (Air forms, Free forms, Fabric forms).
  
  Thin Skin Concrete
  Thin concrete overlay on different materials.
  
  Expanded Concrete
  Concrete with added expansion additives that foam during hydration making lightweight concrete. We can control expansion through section to achieve different weight /strength ratios in one cast.
  
  Ultra Light Concrete
  Replacing part or whole aggregate with light aggregate such as expanded glass and perlite or synthetic pearls (EPS, XPS, perlite) concrete can become extremely lightweight and at the same time hard and resistant to moisture.
  
  High Density Concrete
  Radiation protection concrete with addition of heavy metals like barite, magnetite, steel or lead.
  
  Green Concrete
  Concrete with recycled aggregate (crushed concrete, brick, plastic, rubber) + active waste ingredients from industry (micro-silica, slag, etc.) has the benefits of energy, CO2 and water savings.
  
  Wear Resistant Concrete
  Addition of corundum or quartz aggregate make it ideal for use in industrial floors.
  
  Waterproof Concrete
  Waterproof concrete is an impermeable concrete used for long-lasting, durable watertight construction.
  
  Water-Permeable Concrete
  Special mix design that leaves voids between large aggregate helps water drainage.
  
  Fast Setting Concrete
  It is a special blend of fast-setting cements, sand and gravel designed to set hard in approx. 20 to 40 minutes.
  
  Light Transmitting / Translucent Concrete
  Concrete with Fiber-optic glass and acrylic inserts that transmits light trough section.
  
  Color Changing concrete
  Temperature dependent color changing concrete.
  
  Glow in the Dark Concrete
  Addition of special self-illuminating aggregate and post processing (grinding / washing) makes concrete that glows in the dark or under UV light.
  
  Water Sensitive Concrete
  Changes color when wetted and different patterns or inscriptions become visible. It turns back to normal color after surface is dried out.
  
  Decorative Metal concrete
  An exclusive line of decorative metal powders and shavings-based concrete with unprecedented surface attractiveness (brass, bronze, copper, silver, corroded steel, stainless steel).
  
  Hairy Fabric Concrete
  Concrete made in special molds that leaves micro fabrics on the concrete surface that looks like hairs.
  
  Magnetic concrete
  Concrete never had magnetic properties until now. We are replacing gravel and sand by coarse and fine magnetic fillers merging the worlds of construction and electromagnetism.
  
  Bio-Concrete
  Porous concrete with biologically nutrients, lime and organic materials (straw, sawdust, hypertufa, flower sponge, cork) suitable for the growth of moss and plants.
  
  Perfumed Concrete
  Concrete with the addition of essential oils and perfumes that evaporates through time.
  
  Thermal Conductive Concrete
  Concrete with addition of different types of graphite that conduct heat for different applications.
  
  Thermal Insulating Concrete
  It is made with special lightweight expanded aggregates or foam and has ability to provide excellent acoustic and thermal insulation properties.
  
  Temperature Resistant Concrete
  Using thermally resistant cement and aggregate, with special care made during and after hydration to dry resistant moisture from concrete, concrete can resist high heat.
  
  Electrically Conductive Concrete
  Concrete that conducts electrical energy can be used for raised computer floors to dissipate static electricity.
  
  Sound Absorbing Concrete
  Using different layers of concrete mixtures with different sound properties are making it sound absorbing or sound reflecting.
  
  Impact and Blast Proof Concrete
  With a use of special plastic behaviour and ductile systems it achieves protection by absorbing the blast load energy as strain energy upon deformation.
  
  Flexible / Bendable Concrete
  Special mix of fibers with different properties and addition of flexible polymers in concrete makes material that does not crack but bends on load.
  
  Rubber Concrete
  Concrete with advanced mechanical and dynamic properties, and benefit of using recycled rubber material.
  
  Internal Self-Curing Concrete (SCUC)
  Addition of polyethylene-glycol helps hydration of cement to occur because of the availability of additional internal water that is not part of the mixing water, optimizing the performance of concrete.
  
  Self-Healing concrete
  Concrete with addition of sodium silicate that reacts with calcium hydroxide to form calcium silica hydrate helps heals cracks and pores in structure.
  
  Self-Cleaning Air-Purifying Concrete
  Contains titanium dioxide, a photo-catalytic material that removes the nitrogen oxides from the air and converts them into harmless nitrate with the aid of sunlight. The nitrate is then rinsed away by rain leaving concrete structure clean.

• Molds │ Casting …

  

  Depending on project demands and concrete mix design, different types of applying methods are available:

  
  • Casting in rigid or flexible molds (fabric forming)
  • Application by hand
  • Rolling of fresh concrete
  • Pressure pumping (top-down / bottom-up)
  • Bending (1 axis or 2 axes)
  • Spraying (dry or wet mix - Shotcrete / Gunite)
  • Rotational molding (centrifugal / template)
  • 3D concrete printing

  Fabric Forming - our favorite 
  Fabric formwork uses flexible textile membranes in place of the rigid formwork panels that are usually used in concrete forming. When wet concrete is contained by a thin formwork membrane, the flexible fabric container naturally deflects into a repertoire of precise tension geometries. This produces naturally efficient structural curves, unprecedented sculptural forms, and extraordinary surface finishes.
  
  From a sculptural / architectural perspective, the use of flexible formworks links concrete to its fluid origins, introducing a new horizon for architectural form and expression.
  
  Fabric formworks can be used to form columns, walls, beams, slabs and panels in both precast and in-situ construction. It has a significant potential for construction and engineering technology in both advanced and basic building economies.

  Fabric forming combined with high-end technology, enables us to create virtually any shape or form.

• Finishing …

  Concrete finishing is a process that strives to create a desired, durable surface. When finishing concrete, timing is crucial and close attention to the condition of concrete is vital.
  
  It can be done on fresh concrete:

  • Polishing
  • Smooth finish
  • Broom finish
  • Salt finish
  • Exposed aggregate
  • Stamped
  • Troweling / floating
  • Edging
  • Staining / pigmentation
  • Hardening / densifying

  Or on hardened and cured concrete:

  • Off form
  • Hand sanding
  • Grinding
  • Polishing
  • Acid etching
  • Sandblasting
  • Edge grinding and polishing
  • Laser engraving
  • Staining
  • Moss growing

• Protection …

  Depending on their location and use, concrete structures are exposed to a wide range of different aggressive conditions – from normal atmospheric carbonation to aggressive influences in polluted urban and industrial environments, plus marine atmosphere and liquid or gaseous chemicals, along with influencers that can damage or attack the concrete and embedded steel reinforcement.

  Different high quality protection systems are applied to concrete to protect it from surface damage, corrosion, carbonation, chloride attack, staining and graffiti.

  Penetrating sealers / Stain repellents
  They block the pores in concrete to reduce absorption of liquids.

  • Invisible hydro- & oleo-phobic (silane / silicates / siloxane)
  • Oil

  Sealers / Film forming
  They form an impermeable layer which prevents liquids from passing.

  • Epoxy
  • Acrylic
  • Polyurethane
  • Wax

  Without protection, concrete changes during its lifetime, which can also have its special charm.