Concrete Bonding Agent : Functions and Usage
Today, we will talk about Bonding Agents for Concrete. We will discuss their types, characteristics & procedures to apply the bonding agents. This definitive guide is too long to be written in one page, so we have divided it into four separate issues. This is the first part of the 4-part article on concrete bonding agents.
Concrete is one of the most generally utilized and adaptable structure materials known to man. Concrete is likewise among the most well-known counterfeit materials on the planet. People utilize billions of huge amounts of concrete each year for raising different structures. The historical backdrop of concrete goes long back. It is clear that it has been being used since old Rome.
A great deal of alterations were made from that point forward. Indeed, with the improvement of science and innovation, structural building gained an equal ground. Furthermore, today with enormous endeavors and investigations, concrete has advanced toward being a vital part in development.
In order to place it in straightforward words – Concrete is a structure material produced using concrete, totals (rock and sand), water, and admixtures (synthetic concoctions that upgrade or change the properties of concrete). Presently, there is part of development synthetic compounds utilized in development.
The development of synthetic compounds industry has an assortment of items, going from concrete admixtures to sealants, grouts, bonding agents and waterproofing synthetic substances. These synthetic substances have a broad utilization in the development business. Such development synthetic substances can expand the strength of concrete or when utilized with various stages and mixes and, in various amounts, numerous different restrictions can be defeated because of them.
Bonding agent is one such substance utilized in concrete and thus, in this article we will talk about bonding agents for concrete.
The absolute first inquiry that strikes our brain is – what is a bonding agent? All things considered, in basic words we can characterize them as – "Characteristic, exacerbated or engineered materials used to join singular members of a structure without mechanical latches."
These Bonding agents are frequently utilized in various fix applications, for example, bonding of new concrete to old concrete, showered concrete at development joint or sand concrete fix mortar to help with accomplishing a solid bond.
There are factors influencing the bonding between the old and new concrete. In this way, let us see what they are.
Principally two elements influence the bonding between the old and new concrete:
1. Strength and integrity of the old surface
2. Neatness of the old surface
Why is a Bonding Agent Necessary?
For the most part, Bonding Agents are utilized in concrete where there is a prerequisite to join the old and the new concrete surfaces. It is likewise used to join the surfaces between the progressive concrete layers.
The essential capacity of a bonding agent is to build the bond strength or let us state to strengthen the bond between the old and new concrete surface. The concrete inside a concrete blend doesn't have any regular bonding agent. Consequently, when new concrete is poured on a current layer of concrete, the current and new poured concrete layer don't in general combine.
When poured concrete layer is relieved, the new concrete will basically choose the top as a different layer. This won't make a solid bond between the two progressive layers. Consequently, when the two layers neglect to carry on like one unit, it will at last influence the presentation and strength of the structure.
A bonding agent (bonding cement) in this manner should be applied onto the current concrete surface to guarantee that the new concrete effectively follows.
The equivalent is likewise valid for floor fixes. The new concrete won't hold fast to the old concrete without the assistance of a bonding cement if concrete with no bonding agent is utilized to fill holes brought about by harm.
While we examine bonding agents for concrete, we should know their attributes. Along these lines, let us see individually.
Attributes of Bonding agents:
1. It gives astounding bonds and functionality.
2. It improves the ductile, flexural and bond strength of the concrete just as mortar.
3. It additionally decreases the penetrability of the concrete.
4. It decreases the danger of breaking.
5. It expands the obstruction against ice and different other concoctions.
6. It empowers simple use and application.
Bonding Agents for Concrete: Let us currently comprehend the different bonding agents that can be utilized in concrete. The fundamental Bonding agents are water emulsions of a few natural materials which are blended in with concrete or mortar grout. It is applied everywhere throughout the old surface preceding fixing with mortar or concrete. Bonding agents for the most part cause entrainment of air and have a clingy consistency in a blend. They are successful just on dry, perfect and sound surfaces.
The most regularly utilized kinds of bonding agents are commonly produced using normal elastic, manufactured elastic or from some other natural polymers. The polymers incorporate polyvinyl chloride, polyvinyl acetic acid derivation and so forth. In the past without bonding agent concrete slurry was utilized.
Notwithstanding, as indicated by 'M. M. Goyal' (Author of Construction Handbook for Civil Engineers and Architects), concrete slurry alone isn't satisfactory for the best possible bond between the old and new concrete. Latex or epoxy bonding agents unmistakably improve the grip of the new concrete or mortar to the old concrete surface.
The bonding agents can be utilized for cold joints. They can likewise improve water impermeability of concrete. They additionally serve for polymer alteration of concrete mortar and concrete. With the expansion of bonding agents in fixed mortar or concrete, the diminished water-concrete proportion can be embraced for a similar usefulness, along these lines lessening drying shrinkage.
Bonding agents can be additionally sorted into two classifications, to be specific, Re-emulsifiable sort and Non-Re-emulsifiable sort. Non-Re-emulsifiable sort is more qualified for outer applications since they are impervious to water.
Presently, there are a few stages we have to follow foundationally while applying bonding agents to the concrete.
Steps to Apply Concrete Bonding Agent
Stage 1: Clean the Surface - It is exceptionally fundamental to have a spotless surface. In the event that the current concrete surface comprises any residue, oil or oil, blooming the bonding agent won't work appropriately.
Subsequently this progression is significant so as to ensure that the bonding agent functions admirably on the concrete surface. Serious cleaning can be accomplished by pressure washing or vacuum shot impacting.
Stage 2: Prepare the Admixture - The compartment of concrete bonding agents must be shaken well before use. The substance must be then emptied in suitable sum into a different bowl and weakened with water according to required consistency.
The entire blend must be blended appropriately. This blend can be utilized as a groundwork. Be that as it may, it is encouraged to adhere to the producer's guidance to choose extents.
Stage 3: Blend the Agent - The following stage is blending. The concrete bonding agent must be blended appropriately and completely. Perusing the directions referenced on the compartment is must. The sum and time for application (after the compartment is opened) referenced on the holder must be followed.
It must be noticed that the sum and time contrasts for various kinds of bonding agents. Improper blending can harm the concrete surface, or the concrete substance probably won't work appropriately. Subsequently it is imperative to adhere to the directions as determined.
Stage 4: Applying the Concrete Bonding Agent - When the concrete blend is set up by joining the bonding agent, it must be applied on a superficial level right away. On the off chance that an excess of time has passed, the essential covering may get dry losing its grip.
Henceforth, the blend must be applied when the concoction is as yet crude and not totally dry. For creation and putting of the concrete, standard guidelines must be followed. When the application is finished, smoothen the surface with the assistance of a trowel and permit it to fix.
Since we now know the means of applying concrete bonding agents, let us further comprehend the sorts of bonding agents.
Latex emulsions are most generally utilized as the oil-in-water type emulsions in cementitious structures. These emulsions contain over half water in certain arrangements. Some have a more prominent level of water obstruction in correlation with the others.
The synthesis of latex emulsions is commonly steady in the concrete/water framework. In any case, all emulsions are not perfect with the concrete. Choice of a proper Latex emulsion for a given application requires a comprehension of its science or, on the other hand, counsel the producer.
Be that as it may, the utilization of the latex without concrete substance in the blend creates a disappointment plane because of the absence of film development at the bond interface. There are various ways these emulsions can be utilized as bonding agents.
As per 'Euclid Chemical', (world-driving maker of claim to fame concoction items for the concrete and stone work development industry), three after techniques can be utilized to alter latex into a valuable bonding agent:
1. Planning slick concrete slurry, composed of latex as a major aspect of the blending water.
2. Utilizing 1:1 water-latex weakened material.
3. By utilizing re-emulsifiable latex, it very well may be mellowed and rewetted upon contact with water.
These latex emulsions which are normally utilized in the development industry are grouped into three classifications. They are as per the following.
A. Acrylic Latex: Acrylic esters are the polymers and copolymers of methacrylic corrosive and esters of acrylic. The physical properties of acrylic latex ranges from delicate elastomers to hard plastics contingent on the polymers utilized.
Acrylic latex is smooth white in shading and comprises 45% strong substance in it. The essential utilization of this kind of latex is bonding new concrete to the old concrete.
It very well may be applied by a brush, brush, splash, roller as cement or trowel as a fixing. This sort of emulsion is utilized in the cementitious mixes in a way like SBR Latex.
B. Styrene Butadiene (SBR): Styrene butadiene (SBR) latex is a co-polymer which is perfect with the cementitious mixes. Be that as it may, if SBR latex is exposed to high temperatures for a significant stretch of time, it might coagulate.
Like Acrylic latex, SBR latex is likewise smooth white in appearance, consisting of strong substance up to 55%. They are fundamentally utilized for bonding new concrete to the old concrete and slim layer fixings. Furthermore, they can be utilized as a mortar bond inside 45-an hour.
As indicated by 'Sika AG' (Sika AG-a Swiss claim to fame concoction organization), coming up next are the employment of SBR.
1. It very well may be utilized for waterproofing of rooftop pieces, depressed chunks, cellars, water tanks, overhangs and so on in mix with concrete
2. It is utilized as a bonding agent for use in fix and putting.
3. For making polymer mortar for fixes, and so on.
4. For treatment for draining and saltpeter activity
5. Likewise, multipurpose mortar admixture can be used for infusion grouts.
C. Polyvinyl Acetate (PVA): There are commonly two kinds of Polyvinyl Acetate latex (PVA) that are utilized for the fix applications in the development business. They are non-re-emulsifiable and emulsifiable. The non-re-emulsifiable structures a slim film that offers incredible water obstruction, maturing attributes and bright security.
This sort of latex is broadly utilized as a bonding agent, for the most part because of its similarity with the concrete. Furthermore, they are additionally utilized as a fastener for cementitious water-based paints and waterproofing coatings.
While, emulsifiable polyvinyl acetic acid derivation latex (PVA) produces a film which can be mollified and rewetted with water, whenever required. This sort of latex grants use of the film route before the use of a water-based overlay. The uses of PVA latex are restricted to utilize where the conceivable penetration of the dampness to the bond line is blocked. They are additionally utilized for the inside surfaces of the cast set up concrete.
D. Epoxy Resin: Epoxy resin is the best resin for superior and lightweight parts. It has an extraordinary bonding capacity and wets out quickly. Epoxy resins are generally utilized in the development field on account of their high compressive strength, solid attachment, compound opposition and other extraordinary properties.
They are accessible for the bonding of new concrete to the old concrete. Furthermore, they are additionally utilized for the bonding of concrete to steel. Epoxy resins could conceivably contain fillers. The items are for the most part accessible in different textures that run from exceptionally filled glue to fluids like that of water.
Epoxies are maybe the most flexible of the basic cements. Albeit by and large portrayed as being solid however fragile, they can be planned to be progressively adaptable without loss of rigidity. They have a capacity of bonding to an assortment of substances productively and can be defined to fix either at room temperature or raised temperatures, under dry or wet conditions.
Epoxies bond well to pretty much every material given the surface is appropriately arranged. The special properties which give epoxies their uncommon attachment attributes are:
a. Restored epoxies offer malleable and compressive strengths as high as, or much higher than concrete.
b. Mixes can be in fluid shape and contain no unpredictable dissolvable, for example after polymerization (relieving), the fluid tar transforms into 100% solids.
c. They stick to most development materials.
d. There are no side-effects during the relieving time frame.
e. There is constrained shrinkage during and after fix.
f. Relieved epoxies have dimensional strength.
The essential utilizations of epoxy pitches for bonding concrete are as under:
1. It is utilized for bonding plastic mortar or concrete to solidified concrete or metal.
2. For bonding solidified concrete or other material to solidified concrete, for example setting dowels in preformed or penetrated openings. Utilization of epoxy glues for joining pre-thrown concrete basic components during erection.
a. In this strategy, precast box segments are brought down progressively into the right spot as cantilevers from the extension docks or building section. High strength epoxy being utilized as the jointing (auxiliary sticking) material. The entire series of fragments is made nonstop by post-tensioning them.
3. Applying slip safe or defensive coatings to solidified concrete, bituminous concrete or metals.
4. Getting ready epoxy resins mortar or concrete for fixing spalls and different deformities like splits in concrete or imperfections in metals.
The accompanying system is suggested for its application:
1. Plan just that sum which can be utilized inside the pot life (the time taken from starting blending of the resin and the restoring agent to the moment that the thickness of the blend turns out to be so high as to render the blend unacceptable for application is called pot life) of the item at the current temperature.
2. The segments ought to be altogether blended by hand mixing or with a mechanical blender.
3. Bonding agent ought to be applied by brush or roller to in any event 0.25 mm film thickness.
4. Plastic concrete or mortar ought to be applied to the epoxy film while it is as yet tasteless. When the film has been relieved, plastic concrete won't follow.
Contingent upon the temperature conditions, it is for the most part suggested that the epoxy pitch bonding agent be applied sufficiently well ahead of time of putting the concrete in order to stay tasteless.
Arrangement of Epoxy Resins: As per 'ASTM' (American Society for Testing and Materials), the epoxy-pitch bonding frameworks are characterized dependent on explicit perspectives for example type, evaluation, class, and shading.
The bonding frameworks can be named Type I, Type II, Type III, Type IV, Type V, Type VI, and Type VII according to their physical necessities.
As indicated by their stream consistency and attributes, the bonding frameworks can be named Grade 1, Grade 2, and Grade 3.
Likewise, as per the scope of temperatures for which they are reasonable, epoxy gum can be assigned as Class A, Class B, Class C, Class D, Class E, and Class F.
Classes A, B, and C are characterized for Types I through V, and Classes D, E, and F are characterized for Types VI and VII.
As indicated by 'Raymond J. Schutz' (Published in: Protex Technical Bulletin), characterization of epoxy gum as a bonding agent is as per the following:
1. Type I: This kind of epoxy tar is for the most part utilized for bonding new concrete and different materials to the old solidified concrete.
2. Type II: This sort is generally utilized for bonding of newly blended concrete to the relieved concrete.
3. Type III: This kind of epoxy gum is normally utilized for the bonding of slide safe materials to the relieved concrete. They can likewise be utilized as a folio in epoxy mortars and concrete.
4. Type IV: These kinds of epoxy gums are utilized in load bearing applications for bonding solidified concrete to solidified concrete and different materials and furthermore as a folio for epoxy mortars and concrete.
5. Type V: They are utilized in load bearing applications for bonding newly blended concrete to solidified concrete.
6. Type VI: These kinds of epoxy tars are utilized for bonding and fixing segmental precast components with inner ligaments and for range by-length erection when transitory post tensioning is applied.
7. Type VII: These are utilized as a non-stress conveying sealer for segmental precast components when brief post tensioning isn't applied as in range-by-length erection.
Order of epoxy pitches dependent on grade is commonly characterized by its stream attributes, that is its consistency. The grouping is as per the following:
a. Evaluation I: This sort for the most part comprises materials having low thickness that is appropriate for infusion into the breaks just as where the stream is required.
b. Evaluation II: This sort comprises materials having medium consistency that can be utilized for general purposes.
c. Evaluation III: This kind of epoxy sap involves materials that are of a non-listing consistency.
Characterization of epoxy saps dependent on class is commonly accomplished dependent on the test temperatures at which the gel times are resolved. Gel time is only the time span between the start of blending an epoxy framework and the primary arrangement of a coagulated mass inside that epoxy framework.
The order is as per the following:
1. Class A: Under this sort, the epoxy frameworks for use ought to be beneath the temperature scope of 5°Celsius.
2. Class B: Under this sort, the epoxy frameworks for use ought to be in the scope of 5°Celsius to 15°Celsius temperature.
3. Class C: Under this sort, the epoxy frameworks for use ought to be over the temperature scope of 15°Celsius.
Security Tips while Working with Concrete Bonding Agent - It is basic to play safe while working with concrete bonding agents. Following are tips you have to follow:
1. Wear security shoes, hand gloves and wellbeing goggles while utilizing and dealing with the item.
2. On the off chance that the region close to mouth or eyes is influenced, wash with a lot of clean water and take clinical treatment right away.
"The most effective method to bond another concrete to a prior one?" The inquiry is handily posed than done! It is very notable that since the concrete inside the concrete doesn't contain any characteristic bonding agents, the new layer of concrete doesn't adhere to the current concrete surface.
In such case, the new concrete surface will choose it as a different layer bringing about a more vulnerable concrete surface or segment. Here's the place where the bonding agent has a task to carry out. The bonding agent should be applied on the current concrete surface to guarantee suitable attachment between the progressive layers of concrete for its imperfection free, uniform conduct under the heaps.
This article manages each angle relating to bonding agents for concrete including its sort, grade, class, hues, different procedures, precautionary measures, security tips and so forth.
However, while it grasps a great deal, it must be comprehended that there exists a ton of numerous potential approaches to bond concrete layers and a large group of potential factors positively should be contemplated while creation of the soundest specialized choice.