Technology of wet floor screed with expanded clay

Are you thinking about doing some floor renovations? Comprehending the technology underlying expanded clay wet floor screed can significantly impact the final result of your project. Because of its resilience and insulating qualities, this approach is well-liked, particularly in regions where temperature swings are common.

Cement, water, and expanded clay aggregates are combined to create wet floor screed with expanded clay. These aggregates, which are renowned for being strong and lightweight, support the screed’s thermal efficiency and structural integrity. This means that it can be used in both commercial and residential settings with different kinds of flooring.

The ability of expanded clay to lower total floor weight while maintaining strength is one of the main benefits of using it in wet floor screed. This lengthens the flooring system’s lifespan and makes construction easier. Expanded clay’s insulating qualities also aid in heat retention, which over time may result in energy savings.

Using this technology requires careful mixing and preparation. First, a level base must be laid. Then, the screed mixture must be carefully mixed and poured. This guarantees strength and uniformity across the floor surface, which is necessary to produce a finish that is both smooth and long-lasting.

Making educated decisions about your flooring needs can be facilitated by being aware of the subtleties of wet floor screed with expanded clay, whether you’re planning a new construction or renovating an existing space. This post will walk you through the process while emphasizing the advantages and useful factors for a successful finish.

Advantages and disadvantages of expanded clay concrete screed

The foundation of expanded clay concrete consists of porous, stronger expanded clay granules. The screed’s cellular structure permits:

• achieve a high level of floor insulation;
• effectively protect against external noise coming from below the room – good sound insulation;
• level out significant differences in height – more than 10 cm without significant load on the base of the floor (in such cases, the use of a dry screed is difficult due to the difficulty in compacting it – thick layers of expanded clay are poorly compacted with a vibrating plate);
• lay utility networks inside the layer, as well as underfloor heating elements.

As an example, different types of underfloor heating systems function best inside an expanded clay concrete screed because it serves as both a thermal insulation pad that blocks heat transfer and a base for the system’s pipes or cables.

• achieve an even and durable layer in a complex room configuration, which is difficult to do using a dry method.

In buildings with a wooden base or a weakened concrete floor, a lightweight concrete screed with expanded clay is essential because it significantly lessens the load on the floor and beams when compared to a traditional wet screed made of a cement and sand solution.

Cement and expanded clay screeds have additional advantageous and practical qualities.

• long service life;
• successfully, without the formation of microcracks, withstands a large number of expansion-compression cycles under the influence of temperature changes;
• does not lend itself to external factors of destruction: rotting, mold formation, fungal growth, exposure to moisture and household chemicals;
• exhibits resistance to high temperatures – does not burn or deform;
• suitable for all types of flooring.

The drawbacks are too numerous to be concealed by many advantages:

• the need to level the surface of the screed by grinding or applying an expensive finishing coating – the problem lies in raising expanded clay granules to the surface of the solution after pouring the solution;
• large thickness of the screed, at least 7 cm, which eats up the volume of the room. Therefore, in apartments with low ceilings, only cement-sand wet screed, 3 cm thick, is used;

As an example, you can increase the weight of the expanded clay floor screed layer while decreasing its thickness to 4 cm by using sand concrete.

• high labor costs when pouring, which is due to the significant volume of solution for a thick screed.

Preparation of expanded clay concrete mortar

In order to manually prepare expanded clay concrete, you will need:

• expanded clay, with granules of fraction 5-20 mm of grade M600 or M700 (specific density 600-700 kg/m 3);
• fine-grained quarry sand, sifted and washed to remove clay;
• cement grade M400 (use of more expensive cement M500 is allowed).

Solution component ratio

The typical component ratios for floor screed mixture are 3:1:4, where:

• 3 – sand;
• 1 – Portland cement;
• 4 — expanded clay.

But this relationship is only theoretical. In practice, there are a number of issues that must be resolved, which alters the component ratio.

1. Increased strength is achieved by using all fractions of expanded clay – from 5 mm to 40 mm with a simultaneous reduction in the amount of cement. All sizes of granules must be in equal proportions. In this case, the screed layer turns out to be denser and heavier.
2. A reduction in the weight of the screed is achieved by eliminating the expanded clay fraction of 5-10 mm. This mortar mixture will shrink after drying, and therefore it is advisable not to carry out any work on further floor installation until the hydration process is completed.
3. A thin layer of expanded clay concrete in a screed with no shrinkage can only be obtained by using expanded clay sand – fraction up to 5 mm.

Material calculation

The amount of materials needed is determined by the screed’s cubic capacity. This can be accomplished by multiplying the room’s area by the screed’s height. The average thickness of the screed is determined if variations in the floor base’s height are noted.

The density and volume of the screed needed for a specific room can be used to calculate the additional requirements for each type of material.

Density of expanded clay concrete, kg/m3	1500	1600	1700
Material weight in kg, per 1 m3 of solution
expanded clay M700	560	504	434
Portland cement M400	430	400	380
sand	420	640	830

Simpler math is required to determine the number of bags: multiply the volume of the screed by the material concentration in the solution, then divide the result by the bag weight.

Sand is not needed to create a light screed when using M500 cement. What you’ll need for 1 m 3 of floor screed mixture is:

• expanded clay – 720-1080 kg;
• Portland cement – 250-375 kg;
• water – 100-225 l.

Important: When pouring, screed composed of expanded clay and concrete has trouble because it lacks fluidity (it has the lowest class, P1). The solution is mixed with plasticizing additives, like SDO, to improve its mobility. But liquid soap will accomplish the same goal more quickly and affordably. Fill a bucket with 50–100 ml of cement.

Learn how to use expanded clay to make a wet floor screed that works well for building and remodeling projects. To create level, long-lasting floors, this article explains how to prepare and apply this thin, insulating material. Discover how to mix the screed and apply it smoothly over substrates, step-by-step. Recognize the advantages of expanded clay construction, including enhanced acoustic and thermal insulation. Whether you’re building from scratch or renovating, knowing how to use this method will improve any space’s usability and comfort.

Installation of expanded clay wet floor screed

To make your own wet floor screed with expanded clay, you’ll need:

• concrete mixers (can be rented, which is much cheaper than buying);
• buckets;
• rules;
• grinding machine (also for rent).

This is for pouring directly. To do preliminary work, you will require:

• hammer drill, if the beacons are self-tapping;
• level;
• hydraulic level (laser level). Even a novice repairman can screed a floor using a self-leveling laser level. This tool will help determine the minimum layer of screed, easily mark places for installing beacons and simplify the process of drawing out a plane when installing a number of beacons. Advertising, R-DISTRIBUTION LLC, ERID: LjN8Juyiz.

• roulette;
• construction cord;
• linear profiles for beacons;
• screwdriver (not required for beacons on cement-sand piles);
• mason"s trowel.

Step-by-step instructions for laying expanded clay concrete screed

There are several steps in the screed pouring technology that must be completed in order.

Floor base number one. Wall number two in the room. Layer 3: Waterproofing. 4. Tape for elastic damping. 5. An enlarged layer of clay. Beacon lines number six. 7. A sand and cement-based mortar screed.

Setting up the foundation. The floor base’s readiness for screed laying determines the floor’s service life and, consequently, the floor covering’s service life. The concrete base is cleared of all dirt, debris, paint residue, and pieces of the previous screed.

Repair mortar is used to seal in any existing cracks.

In this instance, large cracks are reinforced (a recess is cut across the crack, into which a reinforcing rod is placed) and microcracks are widened, otherwise the mortar will not penetrate them.

To ensure better adherence of the solution to the floor concrete, the entire concrete surface is carefully primed with special compounds (Ceresit ST 17) if waterproofing is to be done over a screed.

When installing wooden flooring, the boards’ quality and how well they are fastened to the joists are examined. Boards that are rotten or drooping are removed, and those with weak nails are further fastened with self-tapping screws. All cracks and fallen branches are sealed with a 4:1 mixture of sawdust and oil paint, which you can make yourself, to prevent concrete leaks. Special parquet putty is available for a slightly higher price.

The vegetation is removed, and the soil is leveled. You can insulate the floor by pouring sand onto the surface after expanding clay. Water is poured onto the sand, and it is then compacted.

You can view the material "Preparing the base for a floor screed," which contains comprehensive instructions for carrying out this kind of work, here.

Sealing with water. Waterproofing is a mandatory requirement for floor installations. It is executed with the aid of two technologies:

1. “floating screed”, when the insulating layer is laid between the base of the floor and the screed;
2. “floating floor” – waterproofing is carried out along the top of the screed layer.

It’s important to note that expanded clay concrete floor screeds effectively block noise, negating the need for additional soundproofing.

You can use bitumen, impregnating waterproofing, polyethylene film, or roll materials when installing waterproofing beneath the screed.

Everywhere, including individual homes and apartments, uses the movie. Because of its simplicity of installation, you can do the waterproofing yourself. The least expensive choice in terms of price. One drawback is that it cannot be utilized if utility networks are located beneath the screed.

Rubber and bitumen are included in the category of coating waterproofing. Apply in multiple layers using a paintbrush or roller.

Penetrates every crevice, ensuring effective waterproofing. Impregnated waterproofing, as exemplified by Penetrat, is a relatively new but highly successful water-resistance technique.

Applyable to any side of the concrete base, the impregnation produces unique crystals that pierce to a depth of 1 mm and provide water resistance through chemical reactions with its constituents. Go here to learn more about waterproofing.

Beacon installation. Establishing the screed line is the first step in beacon installation. This is accomplished by making a mark 1.4–1.6 meters up from the floor on the wall. It will function as the zero line’s (horizon line’s) starting point.

We mark the horizon line around the room’s perimeter using a hydraulic level (or laser level) (this article provides more details on measuring the zero line).

We measure the distances in the room between the floor and the zero line using a tape measure, then we record the measurement results on the wall.

The highest point on the floor is indicated by the shortest line. We determine the screed line based on the requirements for the screed, which determines its thickness. This is accomplished by cutting the smallest measurement segment by an additional 7 cm (the typical thickness of expanded clay concrete screed is taken), and then marking a line that will serve as a guide for the installation of beacons.

Mark the two outer rows at a distance of 10–20 cm from each other, close to opposing walls, in order to achieve this. After calculating the number of beacon lines by dividing the distance between the marked rows by the rule’s length, we mark each beacon line’s location on the base.

Self-tapping or cement-sand mortar beacons are also possible. Self-tapping screws are the most straightforward method of installing linear beacons. However, the tightness of the insulation is broken when they are screwed into the floor base of polyethylene film and rolled materials, making their use unfeasible. Thus, in these situations, linear beacons are put on top of alabaster or cement-sand mortar piles (rotband is the best option).

Although the technology is straightforward, it must be used with caution because it is possible to cross the line by inadvertently touching one of these beacons before they secure:

1. Along the line of the lighthouse, piles of mortar are made. The outer mounds are located close to the wall, and the rest are at a distance of 40-50 cm from each other. The piles are formed up to the height of the screed line;
2. Using a rule, a linear profile and a level, we achieve coincidence between the line of the screed and the top of the profile laid on cement mounds. To do this, carefully cut off their top with a spatula (trowel), if the height is exceeded, or add mortar to raise the laid profile;
3. Fix the guides with a solution.

Here is additional information regarding beacon installations and types.

The damper tape installation process. This kind of work is required: the damper tape must be fastened to the wall around its whole perimeter.

Two rows are used if the tape’s width is insufficient to support a thick layer of mortar. It must also be fastened at least one centimeter above the screed at the same time. attached to the wall using construction staplers or double-sided adhesive tape.

Be aware that the tape is glued to any roll materials or film that were used to waterproof the floor’s base. Using a stapler is not permitted.

The damper tape’s functional goal is to offset the expansion of expanded clay concrete caused by temperature changes. If not, the screed’s surface will begin to fracture and eventually the floor will be destroyed.

Preparation of the solution

It is necessary to soak all of the expanded clay in water until it is saturated before beginning to lay the screed. Failing to do so will cause the hydration process to stop because the hydrophobic properties of expanded clay granules will pull water out of the solution. Instead of a single structure, there will be fragments of expanded clay concrete combined with small pieces of unbound cement and expanded clay granules.

In a concrete mixer, expanded clay that has been moistened is placed. There are also added specific amounts of cement and sand. Pour in the liquid soap and water. Water should be added while stirring to achieve a homogenous consistency.

Stirring continues until all of the expanded clay granules are covered in cement and turn a complete gray color.

The granules’ surface shouldn’t have any brown patches if the ratios of each component are selected correctly.

Filling the screed

Compared to cement-sand mixtures, the prepared expanded clay concrete solution sets more quickly. It should therefore be installed as soon as possible after mixing. Beginning at the far corner, the procedure is followed along a single row of beacons. It is the rule that performs alignment. They fill the whole floor, going through each row in turn. Your back to the door as you complete your work is required.

Be aware that there are no established definitions of dry and wet screed in popular education articles about using expanded clay concrete as a floor screed. There’s confusion because some people think of this kind of screed as a dry method, while others think of it as a wet method. This time, the problem is easily fixed. One way to classify semi-dry screed is by using one-third part water. This requirement is not satisfied when combining expanded clay concrete mortar. We have a wet screed as a result.

To stop the screed from cracking from the water evaporating too quickly, it is moistened on the first day and then once every two days for a week.

How long does it dry

After 28 days, this kind of screed reaches its maximum strength. You can then install any kind of flooring after that.

Installing laminate after two weeks is also acceptable, according to a number of materials. There is one but, though. Uneven surface caused by granules of expanded clay will undoubtedly rise to the surface. A substrate beneath the laminate does not make up for these drawbacks. It will need to be ground.

In this instance, the solution’s shrinkage may cause beacons to emerge on the elements’ surface. Grinding is not possible in this situation. Self-leveling mixtures applied to the screed’s surface provide a solution to the problem. They require time to dry as well. We can therefore only resume work after a month.

Although leveling the screed surface is a costly procedure, this is one of its drawbacks.

It is clear from studying the technology of wet floor screed with expanded clay that this approach has a lot to offer contemporary building projects. Builders can create a base that is both lightweight and sturdy, while also effectively insulating against sound and heat transfer, by combining cement with expanded clay aggregate.

The ability of expanded clay to lower overall structural weight without sacrificing strength is one of the main advantages of using it in wet screed. Because of this, it’s especially appropriate for renovations and higher floors where load-bearing capacity is an issue.

Furthermore, adding expanded clay granules improves the floor’s thermal efficiency, which eventually results in energy savings. This is particularly helpful in regions where temperature swings are frequent.

Furthermore, laying wet floor screed with expanded clay is not too difficult; however, careful mixing and application are necessary to achieve the best possible results. Compared to more conventional approaches, this technique not only allows for quicker construction schedules but also results in lower labor costs.

To sum up, wet floor screed with expanded clay is a great choice for contemporary building projects looking for economical, eco-friendly, and effective solutions. It is a favored option for many applications in construction and remodeling projects due to its capacity to strike a balance between thermal and acoustic insulation and structural integrity.

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