There are many ways of treating concrete floors once they have been placed. This depends on the performance which is required for the designated client. This could be polished concrete, an epoxy coating, a resin, or just even sealed. Such treatment has a positive effect on the floor’s functionality and other similarly important issues.
According to Joseph Dacosta, Regional Sales Manager Laticrete Africa, properly cured concrete has an adequate amount of moisture for continued hydration and development of strength, volume stability, resistance to freezing and thawing, and abrasion and scaling resistance.
“Curing of concrete is done to maintain the Optimum moisture content (OMC) to prevent the loss of water which is required for the hydration of cement, to avoid shrinkage cracks and premature stressing or disturbance in concrete.” Said Manav.
Reduced maintenance costs, Abrasion resistant concrete floor dust proof and lower absorption are some of the key benefits of polishing concrete floors. This could be polished concrete, an epoxy coating, a resin, or just even sealed. Such treatment has a positive effect on the floor’s functionality and other similarly important issues. This is according to Louis Downes, Head Sales Far East and America of Becotreat , a company popular for its Becosan product which is is a grinding and polishing system designed to treat power troweled concrete floors. The system removes the micro-roughness and with the application of the BECOSAN Densifier and Protective Sealer it creates an easy to clean dust-proof concrete surface.
Mr. Christophe BAUDE, Technical expert of OMNOVA Solutions notes concrete surface treatment plays a crucial role in cement curing “It helps to regulate water evaporation, which optimizes the hydration mechanism and therefore the mechanical properties of the cement. This feature is key in countries with high temperatures, which raises the risk of a too quick evaporation leading to poor curing of cement that endangers the cement mechanical properties. Coatings based on styrene acrylic binders like PLIOTEC® SA40 from OMNOVA Solutions are able to provide this performance. Due to extremely high pH, alkalinity resistance of membrane plays a crucial role in cement curing.”
“In addition, the cement may further benefit from a “sealing” effect providing it an additional durability. This “sealing” aims to provide further resistances, in particular against UV exposure, especially appreciated in countries with large hours of sunshine. This kind of coatings are preferably based on pure acrylic chemistry, like PLIOTEC® PA90MT from OMNOVA Solutions,” said Mr. Christophe BAUDE.
When assessing the sustainable aspects of concrete buildings, durability is one item of interest. According to Steve McDonald of McTech Group, “More durable building assemblies—whether they are walls, floors, or roofs—contribute to overall sustainability by increasing the life span and decreasing the need for repair and maintenance. Concrete floors are common in commercial and industrial structures no matter which material is used for the structural frame, so anything done to increase concrete floor durability has sustainability benefits for the entire building.”
Mr. Riley, Director of Business Development at Crete Colors International notes that after concrete hydrates and cures, the concrete surface has calcium hydroxide, which is a soft, weak compound that releases dust into the air. Silicate hardeners convert the soft calcium hydroxide into strong calcium silicate hydrate. “This is a strong benefit and element as it fills the pores of the surface of the concrete and creates a hard, strong, abrasion resistant, and dust proof surface. Concrete surfaces left untreated will scratch easily, release dust into the air, and become stained and dull.”
Surface preparation methods for concrete floors
As a first step, all traces of calcareous salt, grime, oil and paint stains should be removed from the concrete floors to be treated. Next, all laitance must be removed from the floors. Laitance refers to a layer located on top of a concrete surface, consisting of water and fine sand known as filler, which rises to the surface while the concrete surface is being floated. When laitance hardens, it forms a dense but brittle layer. The laitance layer needs to be removed in order for the primer — which is used in the surface treatment of concrete floors — to be able to penetrate the porous concrete properly. Laitance can be removed either mechanically or chemically. An untreated concrete floor should be covered with protective covers during construction-phase painting and installation. This will prevent the need to remove oil or paint stains at a later stage.
Grinding is the most widely used method of removing laitance layers and other impurities. The process of surface grinding removes all fine laitance and other traces of weak surface layers from the entire floor area, revealing the fine-grained aggregate.
Surface grinding can be regarded as a minimum requirement in the preparation of industrial facility floors. The process of in-depth grinding removes a floor’s surface layer from the entire floor area, revealing the coarse aggregate.
A concrete floor can be scarified using a pneumatic, electrical or internal-combustion driven milling cutter, which creates a rough surface and removes all of the laitance. This is a highly effective and efficient technique, especially for the removal of oily or grimy surfaces from old floors, and of coating films and peeling paint surfaces. When performed correctly, scarifying is carried out twice, with the second round being performed perpendicular to the first.
The form and depth of the marks left by the milling cutter depend on the type of cutter (its steel type) used and the cutter’s depth adjustment. Different cutters are available for different surface materials. Hard metal cutters are normally used in the scarifying of concrete surfaces. Dust nuisance can be alleviated by using milling cutter devices connected to industrial extractors.
Shot-blast cleaning is one of the most efficient methods of removing laitance, grime and poor surface material.
In shot-blast cleaning, steel pellets are blasted with huge force at the floor surface to be cleaned. By varying the pellet size and velocity, it is possible to adjust the efficiency of the cleaning process and the resulting surface profile.
A shot-blast device is constructed in such a manner that all loose laitance, all dust and all steel pellets can be collected using an extractor. The device separates cement dust from steel pellets, which are recycled during the cleaning process until they themselves turn to dust and are deposited in the dust container. After a shot-blast cleaning operation, a separate vacuuming process is usually unnecessary. If the floor has deep potholes or cracks, shot-blasting may leave steel pellets within such fissures. Should this be the case, all pellets must be removed before the coating is applied.
Shot-blast cleaning is practically dust-free. As a cleaning method, it is ideal for the removal of laitance from even, hard industrial cement floors. However, shot-blast cleaning may be too efficient for the removal of laitance from hand-floated cement floors. The surface profile left by the device could be too rough if the blasted floor is to be coated with only a thin paint or varnish coating. Shot-blast cleaning is also suitable for the cleaning of horizontal steel and asphalt surfaces.
Etching with hydrochloric acid
During etching with hydrochloric acid, the laitance layer is dissolved in hydrochloric acid, forming a calcium chloride solution and sludge consisting of filler material and silicic acid. The resulting sludge is practically neutral. If the floor to be etched contains grease, oil, grime or a similar substance, such impurities must be removed using an emulsifying preparatory washing, before etching with hydrochloric acid is performed.
Eng Charles Idowu the Technical Director at CoverTec Products insists that, the use of extremely small size (Nano) molecular technology in product formulations allows the production of ultra-thin water based coatings and surface treatments that bond covalently to the surface. “The results are sealers with much greater adhesion and increased durability when compared to conventional surface treatments,” he said.
CoverTec Products is a manufacturer of floor, roof and wall waterproofing maintenance products. “Using nanotechnology, we produce an ultra-thin protective surface layer that is low in VOC (low emission) breathable and extremely oil and stain resistant. Our sealers do not lift and flake like standard sealers and coatings,” said Eng. Idowu.
“Unfortunately, we see too many flooring projects that are ruined in the first few months simply because the surface has not been adequately protected. Understand that floor hardeners are not acid or motor oil resistant. Water repellents are not going to protect your concrete against brake fluid or food stains and grease. Make sure you ask the floor treatment suppliers for products that will protect against your specific exposure conditions and level of traffic,” affirmed Eng. Idowu.
Factors to consider when purchasing and applying a concrete surface treatment
Andrew Dekker National Operations Manager at Tal insists that the client should specify the performance and products they actually need for the specific job. “Ensure they are applied correctly and perform to your requirements and also use an ISO certified supplier with a track record,” he said.
Tal is a major player in tile and construction adhesives with a track record of more than 40 years “We manufacture our products in South Africa, Kenya, Egypt and Tunisia. We export from these manufacturing units to 25 African Countries. Majority of our products are water based and environmentally friendly. If available we also use recycled material but this depends on sophistication of the recycling market in particular African countries,” asserts Mr. Dekker.
“Discuss in detail with the material manufacturers your actual requirements. It is standard practice to follow old outdated specifications,” said Mr. Dekker. “Education and training is required for the whole market,” he added.
According to Komsol Group Senior President Toni Schonfelder it is best to consider the lifetime and no maintenance of the concrete curing systems during a purchase. He further advices for a no maintenance type of concrete curing systems as it’s cost effective.
Komsol is an International Distributor of control Innerseal and control Topseal products used for protecting against damp problems in a wide range of buildings built in concrete. “Our product extends the lifetime of concrete by 2,6– 3 times times, making the concrete stronger by at least 30%. It is resistant against all chlorides, 100% ecological and can be used for drink water tanks.”
Julie Holmquist, content writer at Cortec® Corporation, comments that budget, degree of corrosion protection, type of inhibiting action, and whether or not there is a desire for water repellency are important factors for choosing the best surface treatment for the situation.
“Our MCI® surface treatments are available with different types of water repellents and different levels of inhibitor concentration. Some have a greater percentage of water repellency with a smaller dose inhibitor, while the MCI®-2020 series has no water repellant but contains a significantly larger percentage of Migrating Corrosion Inhibitor. The choice will vary depending on budget and type of protection needed. Another consideration is whether corrosion inhibiting action is desired at the level of the rebar. Some non-MCI® corrosion inhibiting products only provide protection by sealing the surface from ingress of contaminants. This works well until a breach or a crack allows corrosive elements to enter and reach the rebar level. Migrating Corrosion Inhibitors have the advantage of protecting below the surface even after cracks occur,” said Julie.
While searching for materials that meet your budget, Ian Shaw Mnaging Director at Rust-Tech, points out “keep in mind that the cheapest option isn’t always the best one —and could end up costing your clients a lot more in the long run. At first glance, epoxy appears to have a smaller “per-gallon” cost, but the overall cost per square foot evens the playing field. Although polyurea seems to have a relatively high material cost, when you consider cost of labor and area covered, it saves you and your customer money in the long run.”
During application, Ulrich Meyer, Managing Director of Ha-Be Betonchemie suggest an even application to achieve a fully covered concrete surface. The German based company develops highly effective chemical solutions for ready-mix concrete, precast concrete and manufactured concrete products as well as concrete colours and fibres. They offer different product ranges for these applications in their assortment.
It is also notable to consider the air temperature influence curing effect during application Zapple of Horse Construction points out that high temperature promote curing rate , low temperature slow down curing rate.
Horse Construction is a Chinese company popularly know for its Hm- 120 L Concrete crack injection adhesive product that is a a two component modified epoxy resin adhesive with low viscosity liquid, its viscosity is low, less heat, relaxed mixture ratio, along pot life, the slurry infusion process is simple. The products are widely used in crack glue injection repair of concrete bridges, roads and other projects , and reinforcing glue injection repair of concrete internal cellular, looseness and other defects, anti-corrosion construction of structural surface coat.
Miguel Angel Ruiz, Business Line Manager for Building Chemicals of Bozzetto Group, explains that “another very important factor to have a good quality concrete after the curing time is the quantity of bubbles in the mix that will be affecting on the compressive strength obtained.”
Bozzetto Group is focused on super plasticizers for concrete application since more than 50 years. Able to adapt to the different customer needs, the company’s naphthalene sulfonate superplasticizer, FLUBE®, and polycarboxylate superplasticizer, SUPLA®, makes the concrete reach optimal properties and an accurate quantity of air.
Mario Baggio of Alchemco manufactures points out that it is important to follow good engineering practices for curing the concrete for better results. Alchemco manufactures several waterproofing products for concrete. Their main product is TechCrete 2500 Waterproofing Agent, a formula that penetrates in the concrete and forms a sub-surface membrane to protect the concrete from the water. This product has the ability to seal cracks up to 2mm and cracks that are developed after application up to 3mm. We have a unique formula sold in dozens of countries since late 80’s.
Nicole Herrmann, Product Manager at KEIMFARBEN GMBH suggest when purchasing concrete curing systems it’s important to note what your focus is “A differentiated diagnosis of the concrete surface that needs treatment opens up an entire row of individual protection and design possibilities. Concrete can be whitewashed, stained, painted or coated with a render material. It can also be treated with a water repellent or CO2 protected. Any design variant provides a different appearance and impression,”
“The binder of our paint is one of the most important components determining a coating’s life and durability. The binder ensures connection of the different ingredients to each other and adhesion to the surface. Keim’s mineral silicate “water-glass” binder is completely compatible with concrete and forms permanent chemical bonds, and is not degraded by U.V. Ordinary paints adhere by sticking to the surface of concrete mechanically and acrylics are rapidly degraded by U.V. Our KEIM CONCRETAL® paints and stains are far more natural in appearance protecting and beautifying concrete without making it appear “painted”. Latex and acrylic paints look synthetic and add angular sheen to concrete,” adds Nicole.
Technology trends and breakthroughs
Stefano Di Cesare of Klindex argues that, Africa holds enormous potential and that is why they are always keeping an eye open to the floor treatment scene in order to improve their retail and making their brand stronger. “We continually invest time and money in research and development in order to offer the best products available to world-wide customers,” he said.
Greg Cabot, Digital Marketing Manager of Ameripolish notes that once people understand how to maintain their floors, the life of their floor far exceeds their expectations and aesthetically is pleasing as well.
“I have noticed that people are starting to better understand maintenance procedures with polished concrete. As a company we try to make try to simplify our client’s task by creating latest technologies in concrete maintenance such as our Composite Resin Abrasives which also comes in as technology breakthrough in the market,” said Greg.
Danish Concrete Hardener Company sees making concrete with only 10% cement with the same characteristics as the normal treated concrete as a technological breakthrough in the market.”We are working making such a concrete but with improved strength of up to 200%. The process entails reusing old concrete by grinding it and adding 10%cement to it, afterwards treat it with our product,” Jeep Veenhouwer Sales Manager.
According to construction chemical sales of AK CHEMTECH Joshua Kim, the company’s PCE(Polycarboxylate Ether) is a new generation of concrete admixture raw material that shows drastically low concrete viscosity and adequate robustness;properties Joshua points out is needed in the African market. “ PCE still is, and will be needed to show high performance such as high-strength, high-flow ability,in various W/C ratio, but now we have PCE which is more concentrated on ‘work ability’. This is the strong part of AK ChemTech that will bring you the optimum solution both the quality and the price.”