The emergence of new technologies on the market is usually accompanied by widespread advertising of positive and unique qualities specific products. Plastic fiberglass reinforcement appeared not so long ago, but during this time users have identified many and negative properties material, and in some cases dispelled myths about the stated benefits.

When choosing between fiberglass and metal, you should take into account the real performance qualities of the material, which will be discussed.

Low modulus of elasticity

Expert opinion indicates that plastic reinforcement inferior to metal in terms of tensile strength. This is due to the low elasticity threshold, which entails deformation of the rods during operation.

Here we should remember the primary function of reinforcement. In essence, it is a fastening frame, protective concrete structure from sprains. Being in a normal state without external loads, both metal reinforcement and fiberglass rods do not stretch.

However, concrete has a much lower modulus of elasticity, that is, susceptibility to deformation in the form of tension, and this creates stress on the reinforcement. Respectively, fiberglass is more susceptible to this pressure, which reduces its effectiveness as a concrete fastening element.

Insufficient heat resistance

Although the material has sufficient protection from the effects of fire and is self-extinguishing, such fittings Can only be used in environments with limited thermal exposure thresholds.

According to various estimates, the loss of performance qualities of the composite begins within 300-400 °C. The threshold of 600 °C is critical, but concrete itself is not able to withstand such impacts.

In particular, the reinforcement loses strength, its fibers can delaminate as the process of destruction of the connecting components begins. But it is worth noting that this restriction does not apply to most residential properties. It is worth carrying out design calculations regarding the resistance of fiberglass reinforcement to thermal effects in cases where construction of industrial and production facilities is planned, in which high-temperature heating is assumed.

Elimination of welded joints

Expert opinion is unanimous on this issue. Fiberglass rods must not be connected using welding machines . Therefore, builders have to evaluate the possibility of using alternative means of forming a strong reinforcing frame.

For those who are also looking optimal ways, how to knit plastic reinforcement for the foundation, it is worth considering two options:

There is another approach to forming compounds. He assumes equipping fiberglass rods steel pipes at the ends. Actually, these complementary elements are subsequently fastened together by welding.

The myth of equivalent substitution

Among the first points devoted to the positive properties of fiberglass reinforcement, manufacturers note high strength. One cannot argue with this, but negative reviews of plastic reinforcement for foundations also affect its other qualities, in totality of characteristics cannot be an equal replacement for metal. Moreover, statements about an equivalent replacement do not correspond to reality, both positively and negatively.

Expert opinion confirms that, in terms of strength criteria, metal reinforcement can be replaced by a fiberglass analogue with a smaller diameter. It would seem that such disparity is even a plus. But, if you take a comprehensive approach to assessing the performance properties of a material, you will find serious imbalances.

For example, 8 mm fiberglass reinforcement will provide the necessary structural strength, but the same modulus of elasticity will negate this advantage. As a result, in terms of the totality of qualities, replacing fiberglass rods with 12 mm metal reinforcement will not benefit, providing sufficient reliability to the foundation.

Difficulty of processing

The strength of the material caused a disadvantage in the form inability to bend the rods on the construction site. This operation can only be performed in the factory on special machines. Therefore, when planning the construction of a foundation, it is recommended to initially calculate functionality, which plastic fittings have for strip foundation, agreeing with the manufacturer to carry out additional processing operations.

So, in addition to making bends, it is worth considering the possibility of supplying the rods with the mentioned pipes for subsequent welding.

The construction industry is constantly evolving. New materials that meet high requirements are appearing on the market. Residential and industrial building built in a short time. During their construction, various modern materials And innovative technologies. Recently, the developers were presented with fiberglass reinforcement, which began to compete with time-tested steel rods.

Pros and cons of fiberglass reinforcement

Fiberglass has advantages over steel that are worth considering in detail.

pros

1. Less specific gravity. The weight of the structure is reduced significantly, and this is important in certain construction conditions.
2. Corrosion resistance - does not rust or rot.
3. Its tensile and compressive strength indicators are much better, which is important for the construction of multi-story structures.
4. Resistant to aggressive chemical environments.
5. The range of application at different temperatures is from -60 to +100 degrees.
6. Applicable in any geographical latitudes.
7. Simplicity and ease of transportation. Fiberglass reinforcement is sold in small coils; they are compact, so that, if necessary, they can be transported in passenger cars.
8. Fast and practical installation. You can cut the material with a grinder, and connect the elements together with plastic clamps. But it is worth noting that when working with this material, you need to use protective equipment for both the respiratory tract and your hands.
9. Absolute radio transparency of this type of reinforcement.
10. Advantageous from an economic point of view - the low cost of such material. At the same time, in places where it is necessary to use metal rods with a cross-section of 12 mm, fiberglass reinforcement 8 mm in diameter can be used.
11. Does not conduct electricity, which makes it preferable in the construction of buildings and structures in the energy sector.

Minuses

Despite the positive aspects, there were some disadvantages.

1. Low bending elasticity. If they are designed bearing structures, then this should definitely be taken into account.
   It will not be possible to arrange weld seams on this reinforcement, but this is often impractical if not provided for by the project.
2. Low strength at high temperatures. As soon as the material is heated to 600 degrees, all its strength characteristics completely disappear, since the high temperature changes the structure of the material.
3. Although there are not many disadvantages, they must be taken into account during construction.

Pros and cons of steel reinforcement

Steel products also have their advantages and disadvantages.

pros

1. Time-tested. Standards for the production of material have long been developed. Eat regulations, in which it is indicated steel reinforcement.
2. Various number of rod sections. Available in the range from 3 to 80 mm.
3. Long and predictable service life. Such fittings serve for more than 50 years, provided they do not come into contact with water or chemical environments.
4. Has good bending properties. This material has elasticity 4 times better than fiberglass reinforcement. Its bending strength indicators are much higher.
5. Availability. Sold in many construction markets.
6. Several installation methods. You can tie it with wire, fasten it with clamps or use welding.
7. Environmental friendliness. Negative Impact on human body equals zero.
8. Easy to manufacture anchors. If the rod is heated with a simple torch, then simply bend it into a 90-degree corner. With this in mind, it is easy to manufacture anchor elements right on construction site.
9. Excellent adhesion with concrete mortar. The coefficient of linear expansion of the mortar and reinforcement is almost the same, which makes it possible to obtain a durable tandem.
10. Frost resistance. If the fittings are installed in places with large negative temperatures, then its structure remains unchanged.

Minuses

1. Limitation on rod length. Maximum length steel reinforcement elements are 11.7 meters long; rods 12 meters long are rare.
2. High specific gravity. To deliver this material to the site, special cargo equipment will be required.
3. Tendency to corrosion. When steel is exposed to an aggressive environment or water, the corrosion rate is from 0.1 to 1.5 mm per year.
4. Special storage requirements. It cannot be stored for a long time in an open area or on the ground; the material becomes covered with rust within a few months.

As we see, the shortcomings are not comparable in number with positive aspects.

Comparison of fiberglass and steel reinforcement

1. Fiberglass has greater tensile strength, but steel rods have 4 times higher elasticity.
2. The strength and coefficient of linear expansion of metal reinforcement is greater and similar to concrete, which cannot be said about SPA.
3. Fiberglass does not conduct current, but metal does.
4. Range of cross-sections steel structures much more, so their use on complex construction sites will not replace fiberglass reinforcement.
5. Fiberglass is sold in coils of 50, 100 and 150 m.
6. The cost of composite reinforcement is much less than that of metal.

If we consider the strength of these materials, it is worth considering that fiberglass reinforcement has lower bending strength. When constructing a heavy building, the rods are taken with a larger cross-section than that of the steel material. In fact, the difference in price and the scale of construction remains questionable.

Finally

From comparative analysis It is clear that fiberglass reinforcement is well suited for private construction of houses made of lightweight materials. For the construction of complex and heavy structures, steel should be used. It is difficult to give an unambiguous answer to the question: which is better - steel or fiberglass reinforcement.

The main advantages of composite reinforcement are its low weight, high tensile strength, high chemical and corrosion resistance, low thermal conductivity, low coefficient of thermal expansion and the fact that it is a dielectric. High tensile strength, significantly higher than that of steel reinforcement with the same diameter, allows the use of composite reinforcement of a smaller diameter instead of steel.

You can’t even imagine how beneficial the use of fiberglass reinforcement is! The economic benefit from its use consists of a number of factors, and not just the difference in cost between a linear meter of steel and composite reinforcement.

Don't be lazy to look Full description factors that make up your savings Money, time, man-hours, electricity, Supplies etc. in the article “SAVINGS FROM USING COMPOSITE REINFORCEMENT”

But, you need to remember that composite reinforcement also has significant disadvantages. Most Russian manufacturers do not advertise these disadvantages, although any construction engineer can notice them on their own. The main disadvantages of any composite reinforcement are the following:

• The elastic modulus of composite reinforcement is almost 4 times lower than that of steel reinforcement even with the same diameter (in other words, it bends easily). For this reason, it can be used in foundations, road slabs etc., but application in floors requires additional calculations;
• when heated to a temperature of 600 °C, the compound that binds the reinforcement fibers softens so much that the reinforcement completely loses its elasticity. To increase the resistance of a structure to fire in the event of a fire, it is necessary to take additional measures for thermal protection of structures that use composite reinforcement;
• Composite reinforcement, unlike steel, cannot be welded using electric welding. The solution is to install steel tubes at the ends of the reinforcing bars (in the factory), to which electric welding can already be applied;
• It is impossible to bend such reinforcement directly on the construction site. The solution is to manufacture reinforcing bars of the required shape in production according to the customer’s drawings;

Summarize

Despite the fact that all types of composite reinforcement are a fairly new material on the market construction market Russia. Its application has great prospects. Today it can be safely used in low-rise construction, in foundations various types, in road slabs and other similar structures. However, for its use in multi-story construction, in bridge structures, etc. — it is necessary to take into account its physical and chemical characteristics even at the stage of preparation for design.

An interesting fact - the reinforcement is in coils!

The main application of reinforcement in low-rise construction is its use for reinforcing foundations. At the same time, steel reinforcement of class A3, with diameters of 8, 10, 12 mm, is most often used. The weight of 1000 linear meters of steel reinforcement is 400 kg for Ø8mm, 620 kg for Ø10mm, 890 kg for Ø12mm. Theoretically, you can purchase steel reinforcement in coils (if you find it), but later you will need special device to re-align such reinforcement. Will you be able to transport 1000 meters of such reinforcement in your car to the construction site to reduce delivery costs? Now imagine that the specified reinforcement can be replaced with composite reinforcement of a smaller diameter, namely 4, 6, 8 mm instead of 8, 10, 12 mm. respectively. The weight of 1000 linear meters of composite reinforcement is 20 kg for Ø4mm, 36 kg for Ø6mm, 80 kg for Ø8mm. In addition, its volume has decreased somewhat. Such reinforcement can be purchased in coils, with the outer diameter of the coil being slightly more than 1 m. In addition, when unwinding such a coil, the composite reinforcement does not require straightening, since it has virtually no residual deformation. Could you imagine that you could transport the reinforcement required for construction country house or dacha, in the trunk of your own passenger car? And you don't even need help loading and unloading!

The modern world is changing rapidly, and this also applies to construction industry- new technologies and materials. Today, the use of composite reinforcement in construction is not widespread, and main reason This is due to the lack of information and real, independent reviews from builders. After all, it is much more common and reliable to use good old metal fittings, the characteristics of which are well known and confirmed by time.

But reinforcement made of composite materials has been used in Western countries since the 70s, and has received quite a high rating. Although even there she was unable to squeeze out steel.

In our country, many people still ask: what is fiberglass reinforcement? And they receive a lot of information - both fantastically laudatory (usually coming from the manufacturers of plastic fittings themselves) and very negative (manufacturers of steel fittings do not need competitors either). We will try to calmly and impartially analyze the advantages and disadvantages of composite reinforcement.

How are composite reinforcement produced?

Let's start with the fact that the term “composite reinforcement” combines all types of non-metallic reinforcement produced on the basis different types fibers that are used as a reinforcing base of the rod. The fibers from which the reinforcement is produced can be the following:

• 1. basalt fiber;
• 2. glass fiber;
• 3. aramid fiber.
• 4. carbon fiber.

Thus, the types of composite reinforcement, depending on the applicable fibers, are as follows:

• 1. Basalt-plastic reinforcement, usually black (ABP);

• 2. Fiberglass reinforcement, light yellow in color, however, thanks to coloring additives, the color range is wide (ASP);

• 5. Combined reinforcement (based on fibers of different types).

Any composite reinforcement is produced on the same equipment, the technology is also no different. The only difference is the type of fiber. Currently, there are several production methods:

1. A bundle of fibers, having previously formed a rod - the main reinforcement rod, is impregnated with epoxy resin and pulled out. Then the bundle of fibers is pulled through the shafts, while at the same time a bundle made of the same fibers using resins is wound onto it. Tourniquet in this process performs two tasks - it tightly presses the fibers of the rod, and serves as reinforcement ribs, which will improve the adhesion of reinforcement and concrete in the future. After this, the reinforcement goes through the oven drying stage, and now the reinforcement is ready. This method is the oldest, almost everyone uses it Russian manufacturers plastic fittings.

1. Fiber feeding system (fiberglass, carbon fiber, basalt fiber)

2.Polymer bath (polyester, epoxy resins)

3. Preforming device

4. Die

5.Heating/cooling zones of the die

6.Pulling machine

7.Cutting machine

2. The second method differs from the first only in that the rope is wound onto the rod with very strong force; it is literally pressed into the main rod, as a result of which the ribs are formed from the fibers of the rod itself. Such fittings are more durable than those produced by the first method, since there is no risk of ribs falling off. However, finding similar fittings Russian production almost impossible, since most people use the first method.

3. The third method is also similar to the first, however, the tightening rope here does not form ribs, but only tightens the fibers of the rod until polymerization in the oven. To adhere to concrete, a layer of abrasive - quartz sand - is applied to the reinforcement. This type of reinforcement has the poorest adhesion to concrete, and on top of that, it has the shortest service life. The fact is that epoxy resin breaks down quite quickly alkaline environment concrete, and polyester resins, which are not afraid of alkali, are extremely rarely used by manufacturers in Russia.

4. Finally, reinforcement made using the pultrusion method. In this case, the fibers are formed into a rod, impregnated with polymer resins, and pulled through dies with different cross-sections, arranged in descending order. This method makes it possible to form a periodic relief (ribs) with high accuracy, thanks to which they can be used as a thread (for example, as a tie screw for formwork, with a fiberglass or steel nut). The fittings produced in this way are distinguished by high quality, durability and high price. In addition, such fittings are almost never produced in Russia.

If you search, you can find a completely unusual material on sale - composite reinforcement with an internal cavity. Despite its exotic nature, the tube reinforcement deserves attention - after all, thanks to the cavity, the diameter increases, and with the same number of fibers, the reinforcement with a cavity has large area contact with concrete, which means better adhesion.

Composite reinforcement pros and cons

Like anyone construction material, composite reinforcement has its advantages and disadvantages. Advantages of composite reinforcement:

1. Weight - non-metallic fittings are almost like feathers compared to metal ones. The weight of composite reinforcement is 10-12 times less than steel reinforcement of equal strength. For example, 1 meter of 10 mm plastic reinforcement weighs 100 grams, and steel reinforcement of the same diameter weighs 617 grams. And the fact that plastic rolls into coils allows you to load several coils (the length of a coil is usually 100-200 meters) of reinforcement into the trunk of a car.

2. Composite reinforcement has an impressive tensile strength - 2.5-3 times more than steel (of course, this means with the same diameter). Thus, composite reinforcement with a diameter of 12 mm replaces steel diameter 14-16 mm. Hence the term “equal strength replacement” is used by builders and manufacturers.

3. The cost of composite reinforcement today is lower than that of metal, although a few years ago it was the other way around. Moreover, the price of steel reinforcement is growing steadily, while composite reinforcement remains almost the same.

4. Another plus - composite reinforcement is sold in coils of 100-200 meters, which can significantly reduce the number of scraps when reinforcing structures.

But not everything is so rosy; there are also disadvantages of composite reinforcement:

1. Experts call the main disadvantage of composite reinforcement the low modulus of elasticity, 4 times lower than that of steel - and this is with the same diameter. Of course, this is not a critical drawback; the main thing is to make additional calculations, and it is better if specialists do this. Or our calculator.

2. Composite reinforcement can only be bent in production; it cannot be bent at an angle at a construction site. True, few elements in the form of rods at an angle are usually required, and they can be replaced with steel reinforcement.

3. Fiberglass reinforcement cannot withstand high temperatures - at 100 degrees it ceases to be elastic and breaks easily.

4. Welding when using composite reinforcement is unacceptable, although some experts consider this an advantage. Indeed, when reinforced with either steel or plastic reinforcement, both are mainly tied with wire or plastic ties.

There is an erroneous statement that tying composite reinforcement can only be done with plastic ties (clamps). Of course this is not true. Moreover, we recommend knitting with regular baked steel knitting wire. The process of tying composite reinforcement is no different from tying metal reinforcement. And the goal is the same - to fix the frame until the concrete gains strength, then it doesn’t matter at all what and how the fiberglass reinforcement was knitted.

By the way, it is necessary to say a few words about cutting composite reinforcement. Not everyone knows that it is possible to chop, bite or resaw fiberglass reinforcement, but it is not at all necessary. The best option cut the composite using a grinder. The fact is that biting or chopping creates microcracks, which, although not visible to the naked eye, go deep into the core. Water and alkali get into the cracks, and during freezing and defrosting, the cracks will expand, gradually destroying the reinforcement.

Important! When cutting composite reinforcement, you should take the necessary safety measures - protect your eyes and respiratory organs, since fine dust from basalt or glass fibers is extremely harmful.

Where is fiberglass reinforcement used?

The use of composite reinforcement in construction is quite widespread, although not very widespread in Russia. It is mainly used in the construction of foundations in private housing construction, in the construction of roads, and in the production of slabs. It is often used to create flexible connections between brickwork, to improve the characteristics of walls, etc.

If you have experience using composite reinforcement, please share in the comments!

Composite reinforcement (made of plastic) in last years often competes with conventional steel. This is explained by a number of its advantages. But this material also has its drawbacks and features of its application. Often advertising interferes with an objective assessment of both, and today the article will present the characteristics of this material, talk about its types and areas of application.

Materials for production

Today, the composite reinforcement market is represented by three types:

• fiberglass;
• basalt-plastic th;
• carbon fiber.

Fiberglass reinforcement

The first type of reinforcement is made of fiberglass. This technology appeared in the USSR about 50 years ago. Then printed wiring in radio electronics began to gain momentum, and textolite began to be used as a material for boards, when the base was fabric and the fastening composition was artificial resin. Later, fiberglass was used instead of ordinary fabric, and this expanded the use of fiberglass.

It has found its place in aircraft manufacturing, furniture and household goods, and sometimes even in the military industry. Gradually, it began to be used in construction, and fiberglass reinforcement became an excellent option for foundation frames operating in aggressive conditions - for example, in water.

The materials for fiberglass are glass and epoxy resin.

This material does not contain fiberglass, but basalt. Its manufacturing technology is simpler than glass, because glass production requires several types of raw materials, and basalt plastic- only basalt.

Compared to the previous composite, basalt plastic has a higher elastic modulus and tensile strength, has lower thermal conductivity, but is slightly heavier.

Carbon fiber reinforced plastic

It is made from carbon fiber and the same resins, but this material is expensive. This is due to the production technology of carbon fiber - the basis of such materials. Technological process requires strict adherence to temperature and processing time parameters, since organic fibers serve as the raw material.

Carbon fiber plastics are actively used in the automotive industry, the production of sporting goods, aircraft and shipbuilding, and science.

Carbon fiber reinforcement is stronger than fiberglass and has a higher modulus of elasticity, but it is not without its drawbacks. Thus, the fragility of this material is great, which does not allow its use in long, stressed structures such as floor slabs.

Production technology of composite reinforcement

There are three ways to make composite reinforcing bars. They have English names, which reflect the essence of technology.

Needletrusion- this is the twisting of individual fibers into one with simultaneous impregnation and braiding. Allows you to reduce the cost of the process due to the high speed of such production lines. Giving the relief characteristic of reinforcement is achieved by winding with threads of a periodic profile. The thicker the reinforcement, the larger number threads are used. Thus, rods with a cross-section of up to 10 mm are wrapped with one thread, from 10 to 18 - with two, and above - with four. Products made using this method have good adhesion to concrete due to their relief - and this despite the fact that composite materials have a low adhesion coefficient.

Method plaintrusions consists of pre-forming the main rod and then winding it spirally in two directions.

Most old way production of composite reinforcement - pultrusion. It involves drawing molded, impregnated and already hardened fiber through a system of dies, which, at the polymerization temperature of the plastic, finally gives the reinforcement the required form and pull it out. This method is characterized by a lower production speed and higher cost.

Comparison of quality characteristics

To compare different kinds composite, and also compare them with steel, you can use the following table.

In addition, composite reinforcement has the following properties: fragility what distinguishes it from steel the worst side. Because of this, and also due to its instability to high temperatures, it is not used in structures experiencing strong bending loads and in places where are at risk of fires.

Advantages of the material

Composite reinforcement has a number of advantages over standard steel. These include:

• Increased tensile strength. It can be several times higher than that of steel.
• Corrosion resistance. Plastic fittings do not rust.
• Low heat transfer coefficient. Unlike metal, plastic does not create cold bridges.
• Plastic fittings do not work as an antenna - after all, they are dielectric and diamagnetic. Therefore, the probability of radio interference in structures with such reinforcement is zero.
• Low specific gravity. Steel reinforcement is several times heavier.
• Temperature coefficient expansion is the same as that of concrete, therefore, the formation of cracks for this reason is excluded.

Disadvantages of composite materials

The advantages of composite materials often cannot be fully realized due to the disadvantages that reveal themselves in a number of application cases. This is first of all:

• Low modulus of elasticity. Plastic reinforcement is not rigid, its elastic deformation is in low limits (that is, the ability to return to its original shape after the load is removed is lower).
• Fragility. When bending forces are applied, such reinforcement does not bend, but breaks. In this regard, it is impossible to bend it without heating.
• Low temperature resistance. Fiberglass when reaching 150 degrees loses its positive properties, and at 300 it simply collapses, releasing toxic substances. Carbon fiber reinforced plastics have higher operating and limiting temperatures, since the roads and polymers used in their manufacture are more expensive, but their fragility is also higher than that of other types. Steel can work up to 600-750 degrees before it begins to soften and melt.

Application of composite reinforcement

Composite products have proven themselves very well where static loads are combined with aggressive environment- for example, in hydraulic structures. Sometimes such reinforcement is used on its own, sometimes together with steel, which helps to use the advantages of both types and compensate for each other’s disadvantages.

Plastic products in the form of meshes are actively replacing steel ones in brickwork with cladding, where provided air gap. Steel mesh gradually undergo corrosion, and sometimes this leads to disastrous consequences (a piece of cladding may fall off). The composite has no such drawback.

Equivalent replacement

If we look at the table in the previous chapter and specifications specific products, then the issue of equivalence is decided depending on the conditions under which the reinforced concrete structure will be used.

Yes, indeed, in terms of tensile strength, steel reinforcement in a cross section of 12 mm can be replaced with fiberglass 8 mm, and steel reinforcement 18 with fiberglass 14. But all this is relevant when this reinforcement is needed solely to keep the structure from creeping under load. Simply put, this is how you can make strip and slab foundations.

But in situations where deflection occurs, this rule does not work. Thus, to manufacture a lintel or floor slab, it is necessary to increase the number of rods by 4 times - after all, the elastic modulus of the composite is the same amount less. When the load increases in the middle of a composite-reinforced slab, it will not actually burst, but it will bend more, and the result may be pieces of concrete falling on your head.

Low elastic limit prevents the use of composites for reinforcement concrete pillars. The compressive strength of concrete is quite high, but with increased loads on a small unit area, especially if they are uneven, the modulus of elasticity can have a real impact on resistance to failure.

On this moment the use of polymer reinforcement is regulated by SNIP 5201–2003, and changes have been made to it in the form correction factors to calculate such reinforcement in different conditions operation (Appendix L of 2012).

Main product details

In recent years, the number of companies producing composite reinforcement (especially fiberglass) has grown many times, but the quality of their products leaves much to be desired. Here are some ways to recognize a marriage:

• Pay attention to the color of the products. High-quality fittings in one batch are always the same color. If this is not so, then it has been violated temperature regime in production.
• There should be no cracks or delaminations. They are easy to see in the cut.
• Fiber breaks reduce the declared characteristics. They are also visible to the naked eye.
• Uneven profile (winding). Most likely, the production used old equipment where continuity was broken.

Now the requirements for composite materials will become more stringent. Rolled steel is becoming more expensive, and plastic fittings have every chance of displacing steel ones from a fairly large segment of the market. Undoubtedly, less than conscientious manufacturers take advantage of this, so you should be on your guard.