Technology: reinforcement of concrete surfaces – evolution of strengthening methods

For centuries, concrete has been a fundamental material in construction due to its strength and longevity. However, the need for more effective reinforcing techniques has increased as structures have grown taller and more intricate. The way we strengthen concrete surfaces to ensure they can withstand environmental challenges and the test of time has changed due to technological advancements.

Originally, the main means of reinforcing concrete were crude methods involving steel bars. Although these techniques worked well, they had drawbacks and occasionally caused problems like corrosion. Engineers started investigating novel materials and creative designs to improve the structural integrity of concrete as technology developed.

Modern methods such as fiber-reinforced composites and sophisticated synthetic materials are available to us today. These advancements lighten and increase the adaptability of concrete in addition to increasing its strength. Concrete reinforcement is being approached differently as a result of technological advancements like 3D printing, which enable more intricate and effective designs.

Anyone interested in engineering or construction needs to understand how these strengthening techniques have evolved. Through examining historical innovations and contemporary practices, we can gain a better understanding of our progress and potential future directions. The development of concrete reinforcement has shaped the built environment around us in an intriguing way, combining innovation and tradition.

Types of reinforcement and scope of application

The process of ironing concrete involves rubbing dry cement into a freshly formed surface to increase its strength and moisture resistance. The key is that as the concrete is processed, the amount and size of voids and pores in the base either reduces or vanishes completely, and the cement binder and other materials strengthen the concrete by binding together its brittle structure. This raises the surface’s quality.

Crucial! Work is finished when a reinforcing layer is applied. For example, by this point, the floor’s base ought to be installed and, if required, screeded level.

Several kinds of materials can be used for reinforcement:

• Cement. Previously, ironing of the concrete surface was carried out using only high-grade cement. But a significant drawback of such treatment forced us to improve the technology. The downside is that after some time (depending on the quality of the work performed), the top layer under regular loads inevitably began to peel off and crumble.

• Topping. When preparing a hardening solution, they began to try, in addition to cement, adding other components and microfibers to the composition to improve the quality of adhesion of the coating to concrete and its technical characteristics. Thus, special finely dispersed compositions based on Portland cements with various fillers were developed. They not only enhance strength properties, but also significantly increase resistance to moisture and mechanical impacts. And also impart resistance to aggressive environments and other required qualities to ordinary concrete surfaces. These modified mixtures began to be called topping.

Recall that the primary benefit of multi-component mixtures is an enhanced bond to the concrete base. This implies that the possibility of the reinforcing layer pealing off is minimized with high-quality work.

• Impregnation. Along with topping, polymer coatings for impregnation appeared that do not contain cements. Their main advantage is that the base does not necessarily have to be freshly laid. They can also be used on old surfaces for restoration and repair purposes. Moreover, the method of applying them is also much simpler than cement compositions.

Iron surfaces are more frequently applied after the flooring is coated in order to solidify the base or, in the case of a screed, the upper layer. However, it can also be applied to reinforce vertical surfaces when needed.

Processing intended to waterproof, say, the area beneath the pool, can be done depending on the kind of composition used. Additionally, in production workshops with differing levels of aggression and environmental temperature. The pricing and average consumption data for various materials are displayed in the table.

Ironing Cement

This traditional approach can be applied to private construction. Ironing concrete walkways in places with little foot traffic, such as a summer house’s grounds, a streetside gazebo, and other locations.

Dry method of ironing

You must get ready in advance so that all the required tools and materials are gathered and accessible if you intend to arrange for additional strengthening using the dry method. because a freshly laid base is used for ironing work. This technique is limited to surfaces that are horizontal.

It is preferred that the strengthening cement be of a grade no less than M300.

1. Preparation. Strengthening work is carried out on a fresh, not yet fully hardened base, on which you can already walk, but so that a trace remains. In this case, its depth should not exceed 3 mm. The concrete surface acquires this state of hardening after 3-7 hours, after the end of the work, depending on the hardening conditions.

1. Application. Next, dry cement powder is evenly distributed over the wet surface using a sieve, the thickness of the bulk layer should be 2-3 mm. It is better to apply in small portions along the radius, so that the hand is enough to immediately compact it a little and move on to the next section. However, you can leave it without preliminary compaction.

It is recommended to use a special distribution trolley for applying dry mixtures if the area to be treated is large.

1. Rubbing. As soon as all the dry light gray powder has darkened, it means that it has already drawn enough moisture from the base, and you can begin grouting. If the area is small, then this action is performed manually, using a trowel, float, foam float or similar tools. If there is a lot of work, it is better to use a special device: a grouting machine. The surface should be even, smooth, when using a mechanized rubbing method – almost shiny.

1. After finishing the work, it is advisable to treat the surface with a moisture-retaining impregnation, cover it with a film, and let it “rest” for several hours to improve the adhesion processes. If necessary, you can walk on the reinforced floor after 24 hours, use it more actively on the 4th day. The surface will gain full strength in 28 days.

Wet ironing method

It is advantageous over the dry method in that it can be used to process surfaces that are vertical or horizontal. On a fully fixed base, that is, 28 days following the conclusion of the installation process, the solution is applied. This implies that old surfaces can also be repaired using this technique.

1. Preparation. The area for reinforcement is carefully cleared of debris and dust. To improve adhesion, pre-impregnate the base with a deep penetration primer. Prepare a liquid cement-sand mixture in a ratio of 1:1, with the addition of lime impurity in the amount of 10% of the resulting mass.

To give the solution flexibility and stop cracks, lime is required. You can also add extra ingredients, liquid glass, microfiber, etc., if you’d like. Then, however, using a premade dry topping mixture will be simpler.

It should be noted that using half as much sand as cement will result in a stronger surface.

1. Application. The resulting mixture is laid out in a thin layer on the prepared horizontal base and leveled. A needle roller will help to evenly distribute the solution over the surface. After the coating has set a little, you should cover it with a film. This is necessary to reduce the rate of moisture loss, to prevent cracking.

To ensure that the mixture holds and doesn’t run down the wall, it should be a little thicker on vertical surfaces. Using a pneumatic sprayer or spatula, it can be applied. Before moving on to the next phase, smooth it out and give it time to gather enough strength.

1. Grouting. After the layer has gained the required strength, after about 6 hours, possible roughness is grouted. These works are performed in the same way as in the dry method – using a hand tool or mechanisms. If desired, the resulting reinforced floor can be sanded.

To stop cracks from forming, it’s crucial to set up conditions that slow down the hardener’s drying process. The best materials for this task are specific impregnations and varnishes that form a coating on the concrete surface to stop moisture from escaping.

After all, it’s quite challenging to keep the base covered with a film and leave the room unoccupied for two weeks. You can therefore start to walk carefully on the floor after a day. It will not reach its maximum strength before the typical 28-day concrete curing period.

Calculation of cement mortar

Application of topping mixtures

A hardening mixture called topping is made up of different components and additives mixed with a cement binder. Compared to the traditional method, this approach to processing concrete is more costly and labor-intensive. The production process necessitates an expert approach, and the mixtures themselves are more costly.

However, compared to the surface that was ironed with regular cement, the one that was strengthened by it has better qualities. Another name for the topping technology is "concrete floor armoring."

This kind is better suited for use in industrial settings where floor quality requirements are higher and loads are higher. Or, for instance, in parking garages and retail centers. But since dyes can be added to the mixture, it is also appropriate for decorative floor finishing in residential areas.

There are three basic types of topping mixture compositions based on the type of main filler and the application and intensity of the anticipated loads on the surface:

Filler	Surface load level
Quartz	Medium
Corundum	High
Metal	Very high and extreme

Application methods

Similar to cement ironing, the dry method is more frequently employed for the device that hardens concrete surfaces with toppings. Here, though, the base’s properties will be higher.

How much relies on the specifications of the kind of mixture. Because surface hardening won’t help if it is ill-installed and loose.

Generally speaking, the base must be constructed with cement that is at least M400 in grade. Additionally, the floor’s supporting structures are expertly constructed, with appropriate crushed stone preparation beneath them (for the device that is "on the ground") and reinforcement. in order to prevent subsidences and, related to this, cracking.

Topping mixtures can be applied manually or with the aid of machinery to reinforce the surface of a concrete floor:

• When work is carried out by machine (for the arrangement of industrial-scale areas), there is no division into stages. Everything is carried out by machines sequentially, according to a specially developed laying technology.
• When work is carried out manually, the layer is applied in two stages on top of a base that has not yet hardened firmly (after 4-8 hours, depending on the hardening conditions). If water has come out of it, it must be removed. And also, immediately before applying the mixture, it is recommended to rub the surface of the base. This is necessary in order to ensure better joint work of concrete with topping.

Crucial! Avoid applying too much "friction" as this may cause the coating to dry out and start to peel off.

• First, 0.5-0.65 of the total amount of the mixture is distributed. After the dry powder has gained sufficient moisture, proceed to rubbing the surface. And then, without interruption, proceed to the second stage.
• The remaining amount is evenly distributed, and after wetting it with concrete milk, the primary grouting is performed. After another 2-6 hours, when the coating has gained sufficient strength – such that the trace of shoes remains no deeper than 1 mm, you should proceed to the final grouting and smoothing of the strengthener. If desired, you can polish it to a shiny glossy surface.

It is advisable to apply a moisture-retaining varnish on top of the completed coating. A high drying speed could cause the surface to crack.

This article examines the development of concrete surface reinforcement techniques, emphasizing how technological advancements have made conventional methods more effective and long-lasting. Concrete surfaces are now much stronger, more resilient, and more versatile than they were in the past thanks to technological breakthroughs in fiber composites, smart materials, and early steel reinforcements. We’ll examine significant inventions and their real-world uses, demonstrating how these advancements will continue to influence architecture and construction in the future.

Strengthening using impregnations

There are numerous pregnancies.

They can be conditionally divided into four groups based on their primary objective:

1. Protection during the maturation period of the concrete surface. In order not to suffer, covering the freshly reinforced base of the floor with a film for all 28 days, and periodically moistening it with water to avoid cracking, you can use an impregnation specially designed for these purposes. On the surface, it creates a hydrophobic coating that significantly reduces the rate of moisture release from freshly laid concrete and removes dust from it.

Important: The amount of impregnation specified in the instructions must be applied exactly. The area that has too much coating on it might start to peel, changing the color and appearance overall.

Using these compositions also has the added benefit of strengthening the "young" surface. Thus, on the second day, you are free to use the treated floor without any hindrances (such as plastic bags or boards to walk on). Additionally, the surface takes on a beautiful, shiny, clean appearance, which enhances the facility’s visual inspection during delivery.

1. Decorative colored impregnations. They are used instead of paint, due to the ability of colors to penetrate the concrete surface up to 5 mm. This means that traces of abrasion are not terrible for such a floor for many years.
2. Impregnations for imparting waterproofing properties to structures. They are “more powerful” than the compounds used during the concrete curing period, are resistant to abrasion, and are designed for a significantly longer service life.

1. Strengthening. They often contain inorganic materials. When applied, a chemical reaction of the impregnation with the mineral component of the concrete occurs, resulting in the formation of crystalline bonds. The structure acquires additional coherence and is compacted, which means it becomes more durable and waterproof.

Note: Chemicals or organic components may be used in impregnations. Regarding their technical attributes, they are fairly similar. However, chemical impregnations will come at a much higher cost.

All impregnations, regardless of application group, to a greater or lesser degree:

• Strengthen;
• Dedust;
• Hydrophobize.

Three methods are used to apply them: rollers, brushes, and spraying. There may be variations in requirements for the concrete surface. Certain liquid hardeners need a new base that hasn’t dried yet. Only after it has completely dried can other substances be applied. You will find detailed instructions on how to use each type of impregnation attached.

Watching the video in this article will help you see the variations in ironing techniques more clearly.

As an example, EpoxyPAN is one of the nanomodified components in hardening coatings and primers that have been developed and are currently being used successfully. Crystals grow in the concrete base as a result of interactions with mineral substances at the nanoscale rather than through a chemical reaction.

As a result, the surfaces have a long reserve of strength, complete waterproofness, and many other advantageous properties. A new wave of nano-modified building materials broadens the scope and creates many new opportunities for creative architectural solutions.

Method	Evolution
Steel Reinforcement	Traditional method using steel bars or mesh to improve tensile strength.
Fiber Reinforcement	Added fibers like glass, steel, or synthetic materials to enhance durability and crack resistance.
Post-Tensioning	Involves tensioning steel tendons after the concrete sets to increase load-bearing capacity.
Precast Panels	Off-site fabrication of concrete panels, reinforced for strength and quicker installation.
Geopolymer Concrete	Using industrial byproducts to create stronger, more sustainable concrete with reduced environmental impact.

The development of technologies for concrete reinforcement is a reflection of our expanding knowledge of materials and their uses. Techniques have changed over time, moving from basic steel rebar to sophisticated composites and creative designs. Concrete surfaces are now more durable and perform better, opening up a wider range of applications for them thanks to each new technique.

Contemporary reinforcement strategies prioritize sustainability in addition to strength. Greener construction practices are becoming more prevalent as a result of the use of recycled materials and eco-friendly procedures. This guarantees that while we develop for the future, we also maintain the environment.

It’s exciting to see how smart technologies will be incorporated into concrete reinforcement in the future. The possibilities are endless, ranging from materials that can self-repair to sensors that track stress and strain. These developments hold the potential to produce structures that are more resilient to the forces of nature and the passage of time, in addition to being stronger.

In conclusion, there is always room for improvement in the concrete reinforcement process. By investigating novel materials and methods, we are paving the way for construction practices that are safer, more effective, and more environmentally friendly. This evolution opens the door to a better, more resilient future while also improving our built environment.

Video on the topic

Strengthening the top layer of concrete. LEVL TOP technology

iron plating, errors