{"title":"Concrete Bonding Agents \u0026 Primers","description":"\u003cp\u003eA concrete bonding agent is a chemical primer applied to an existing concrete surface to ensure that freshly placed cementitious material bonds to it as a single composite structure. Without a bonding agent, new concrete, mortar or screed placed over old cured concrete has no reliable means of adhesion. The cement in a fresh mix contains no natural bonding properties of its own, so once cured, a repair or overlay placed without preparation will simply sit on top of the substrate as a separate layer, subject to movement, delamination and water ingress at the interface.\u003c\/p\u003e\n\u003cp\u003eConcrete bonding agents work by penetrating and keying into the pores of the prepared surface, creating a chemically active interface that the incoming cementitious material can grip. Depending on the chemistry, they may also improve the durability and flexibility of the repair zone, reduce permeability at the bond line, and in some formulations act as a barrier to chloride migration. The result is a repair or overlay that performs as part of the original structure, not as an add-on sitting above it.\u003c\/p\u003e\n\u003ch2\u003eWhy new concrete won't bond to old without a primer\u003c\/h2\u003e\n\u003cp\u003eThe fundamental problem with concrete-to-concrete adhesion is that cured concrete is a dense, low-porosity substrate with very little residual chemical activity at its surface. New concrete or mortar placed directly onto this surface without preparation will not bond reliably, regardless of how well it is mixed or compacted. The two layers will cure and shrink independently, and any differential movement, moisture ingress or thermal cycling will open up the interface over time.\u003c\/p\u003e\n\u003cp\u003eSurface preparation addresses part of this problem. Removing laitance, dust, oil contamination and loose material by mechanical preparation gives the new material a roughened profile to key into. But mechanical preparation alone is rarely sufficient for a durable repair. A concrete bonding agent applied to the prepared substrate provides the chemical bridge that mechanical roughening cannot, ensuring that the new cementitious material bonds at the molecular level rather than simply resting against a textured surface. Does concrete bonding agent really work? Applied correctly to a well-prepared substrate, yes, with bond strengths that in the case of epoxy formulations consistently exceed the tensile strength of the concrete itself.\u003c\/p\u003e\n\u003ch2\u003eSBR bonding agents\u003c\/h2\u003e\n\u003cp\u003eSBR, or styrene butadiene rubber, is a polymer emulsion bonding agent used widely in concrete repair, render and screed applications. Applied as a slurry primer, SBR is gauged with clean water and fresh cement and scrubbed firmly into the prepared substrate. The repair mortar, screed or render must then be applied onto the wet slurry before it has a chance to dry. SBR can also be incorporated directly into site-batched mortars and mixes to improve their cohesion, workability, durability and resistance to freeze-thaw cycling.\u003c\/p\u003e\n\u003cp\u003eThe key practical advantage of SBR over PVA-based bonding agents is moisture resistance. SBR does not re-emulsify on contact with water, making it suitable for external applications, renders, waterproof screeds and permanently immersed conditions. It bonds to concrete, masonry, stonework, plaster and blockwork, and can be applied to damp substrates where the surface is prepared but not saturated. Products in this range contain no chloride admixtures, which is a relevant consideration for reinforced concrete repair work.\u003c\/p\u003e\n\u003ch2\u003eEpoxy bonding agents for concrete\u003c\/h2\u003e\n\u003cp\u003eEpoxy resin bonding agents are two-part systems used where the demands of the application go beyond what a polymer emulsion primer can deliver. Where SBR is a general-purpose bonding agent across a wide range of construction and repair applications, epoxy products are specified for structurally demanding environments: loading bays, bridge decks, roads, industrial floors and any situation where the concrete will be subject to heavy trafficked loading or permanently immersed in water.\u003c\/p\u003e\n\u003cp\u003eTwo-part epoxy bonding agents are solvent-free and applied to dry or damp prepared surfaces, but not to surfaces with standing or running water. They provide excellent bond retention in permanently immersed conditions and act as an effective barrier to chloride migration, which makes them particularly relevant for concrete repair in aggressive or contaminated environments. The bond strength achieved by epoxy formulations consistently exceeds the tensile strength of the parent concrete, meaning that correctly specified and applied, the bond line will not be the point of failure. For horizontal and vertical surfaces where new cementitious mortars and screeds are being bonded to existing concrete, epoxy bonding agents represent the technically superior choice where conditions justify the specification.\u003c\/p\u003e\n\u003ch2\u003eApplying a concrete bonding agent\u003c\/h2\u003e\n\u003cp\u003eThe single most important factor in a successful concrete bonding application is surface preparation. The existing concrete must be structurally sound, clean and free of dust, laitance, oil, grease and any loose or contaminated material. Pressure washing and mechanical preparation such as grinding or shot blasting are the standard methods. If the substrate is contaminated with oil or other penetrating materials, preparation needs to go deeper than the surface layer to reach clean concrete.\u003c\/p\u003e\n\u003cp\u003eFor SBR slurry primer applications, the prepared surface is typically pre-dampened but brought to a saturated surface-dry condition before the slurry is applied, with any standing water removed. The slurry is gauged to a workable consistency and scrubbed firmly into the substrate, and the repair mortar or overlay must be placed while the slurry remains wet and tacky. Allowing the slurry to dry before placing the new concrete is one of the most common causes of bond failure and should be avoided.\u003c\/p\u003e\n\u003cp\u003eFor epoxy bonding agent applications, the same substrate preparation standards apply. The two-part epoxy is mixed according to the manufacturer's instructions and applied to the prepared surface. There is a defined working window, which varies with temperature, within which the cementitious overlay must be placed. Working at the limits of this window in hot conditions reduces pot life significantly, so temperature and timing need to be managed on site.\u003c\/p\u003e\n\u003ch2\u003eChoosing the right bonding agent for concrete\u003c\/h2\u003e\n\u003cp\u003eSelecting the correct bonding agent depends primarily on the conditions the repair or overlay will face during its service life. For standard concrete repair mortars, renders, floor screeds and waterproof applications in normal site conditions, SBR polymer emulsions provide reliable adhesion across a broad range of substrates and can be applied to damp surfaces. They are suited to both internal and external use and to applications with permanent water contact.\u003c\/p\u003e\n\u003cp\u003eWhere the application involves heavy structural loading, industrial traffic, bridges or roads, or where chloride contamination of the substrate is a concern, an epoxy resin bonding agent is the more appropriate specification. The higher cost is offset by the superior bond strength, chloride barrier performance and long-term durability in aggressive environments.\u003c\/p\u003e\n\u003cp\u003eIn both cases, the bonding agent selected should be compatible with the repair mortar or cementitious overlay being placed. Manufacturer guidance on mix designs, overlay timing and application temperatures should always be followed, and the product datasheet reviewed before work begins.\u003c\/p\u003e\n\u003ch2\u003eWhy choose Construction Supplies UK for concrete bonding agents and primers\u003c\/h2\u003e\n\u003cp\u003e\u003cstrong\u003eSpecialist Fosroc range:\u003c\/strong\u003e We stock a focused range of Fosroc concrete bonding agents and primers covering SBR polymer emulsions and two-part epoxy resin systems, chosen for their performance in demanding construction and repair environments.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eCorrect product for the application:\u003c\/strong\u003e SBR and epoxy bonding agents suit different conditions. Our team can help you confirm the right product for your substrate, repair system and service environment before you order.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eFocused service: \u003c\/strong\u003eWe supply directly to contractors, groundworkers and concrete repair specialists, with no minimum order value and free delivery on orders over £300 ex VAT.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eTechnical support available: \u003c\/strong\u003eConcrete repair is a specification-sensitive discipline. Call us on \u003cstrong\u003e03300 55 32 02\u003c\/strong\u003e or email \u003cstrong\u003e\u003ca href=\"sales@constructionsuppliesuk.co.uk\"\u003esales@constructionsuppliesuk.co.uk\u003c\/a\u003e\u003c\/strong\u003e if you need guidance on product compatibility, mix designs or application conditions.\u003c\/p\u003e","products":[{"product_id":"fosroc-nitobond-sbr","title":"Fosroc Nitobond SBR","description":"\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eFosroc Nitobond SBR is gauged into site-batched cement mortars to improve cohesion, workability and durability. When incorporated into repair mortars, renders and floor toppings it produces mixes that are highly resistant to freeze\/thaw cycling, with improved tensile and flexural properties that allow thin applications and excellent bond to concrete, masonry, stonework, plaster and blockwork.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eAs a bonding slurry primer, Nitobond SBR is mixed with clean water and fresh cement then scrubbed firmly into the prepared substrate. The repair mortar or topping must be applied onto the wet slurry — the primer must not be allowed to dry before the overlay is placed. A wide range of mix designs is achievable; typical applications include patching mortars, heavy-duty floor screeds and bonding mortars for slip bricks and tiles. Mix designs should always be adjusted to account for the moisture content of on-site sand and aggregate.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eTypical applications include, concrete repair mortars, floor toppings and screeds, to waterproof renders and cementitious slurries and bonding mortar for slip bricks and ceramic tiles\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eBenefits\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eReady to use\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eImproves cohesion, workability and durability of site batched mortars\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eHighly resistant to the freeze\/thaw cycle\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eExcellent bond to concrete, masonry, stonework, plaster and blockwork\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eResistant to hydrolysis, suitable for internal, external and permanently immersed conditions\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eGood to know \u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eCan be applied to damp substrates\u003c\/li\u003e\n\u003cli\u003eNo chloride admixtures\u003c\/li\u003e\n\u003cli\u003eMinimum application temperature: +5°C\u003c\/li\u003e\n\u003cli\u003eImproved tensile and flexural strength, allows thin applications\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e \u003c\/p\u003e","brand":"Fosroc","offers":[{"title":"Default Title","offer_id":57127673430348,"sku":"BM05944","price":66.59,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1046\/6715\/2716\/files\/fosroc-fosroc-nitobond-sbr-1232467377.webp?v=1776264628"},{"product_id":"fosroc-nitobond-ep","title":"Fosroc Nitobond EP","description":"\u003cp\u003eFosroc Nitobond EP is particularly suited to concrete extensions and repairs in demanding environments such as factories, loading bays, trucking aisles, bridges and roads, and in bonded or granolithic floor toppings where permanent immersion in water may occur during service. As well as acting as a mechanical bonding agent, it forms an effective barrier to chlorides and other substrate contaminants, where required as a chloride barrier, two coats should be applied with any surface voids filled with Nitomortar PE between coats.\u003c\/p\u003e\n\u003cp\u003eTypical application include, bonding new cementitious mortars \u0026amp; screeds to existing concrete, bonded \u0026amp; granolithic floor toppings as well as concrete repairs in loading bays, bridges \u0026amp; roads and permanently immersed in concrete repairs.\u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eBenefits\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e100% solids, solvent-free epoxy resin, non-flammable\u003c\/li\u003e\n\u003cli\u003eTwo-part pre-weighed pack, white base and green hardener confirm adequate mixing\u003c\/li\u003e\n\u003cli\u003eCan be applied to dry or damp surfaces (no standing water)\u003c\/li\u003e\n\u003cli\u003eEffective barrier to chlorides and substrate contaminants\u003c\/li\u003e\n\u003cli\u003eExcellent bond retention in permanently immersed conditions\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eGood to know\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eBond strength always exceeds the tensile strength of the concrete\u003c\/li\u003e\n\u003cli\u003ePot life: 35–45 minutes at +20°C\u003c\/li\u003e\n\u003cli\u003eMaximum overlay time: 90 minutes at +20°C \/ 60 minutes at +30°C\u003c\/li\u003e\n\u003cli\u003eCompressive strength: 50 N\/mm² at 7 days\u003c\/li\u003e\n\u003cli\u003eSlant shear bond: 25 N\/mm² at 7 day\u003c\/li\u003e\n\u003cli\u003eMinimum application temperature: +5°C\u003c\/li\u003e\n\u003cli\u003eDo not apply over existing coatings. \u003c\/li\u003e\n\u003cli\u003eDo not apply where there is standing or running water\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e \u003c\/p\u003e","brand":"Fosroc","offers":[{"title":"2.5kg","offer_id":57127673954636,"sku":"BM05945","price":93.97,"currency_code":"GBP","in_stock":true},{"title":"4.5kg","offer_id":57127673987404,"sku":"BM009379","price":170.17,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1046\/6715\/2716\/files\/fosroc-fosroc-nitobond-ep-1232467376.png?v=1776264616"},{"product_id":"fosroc-nitobond-ar","title":"Fosroc Nitobond AR","description":"\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eFosroc Nitobond AR is applied immediately after placement of the repair mortar or removal of formwork to retain moisture and ensure correct curing of Renderoc repair systems. Large areas should be cured progressively as trowelling proceeds rather than waiting for completion of the whole area. In fast drying conditions, supplementary curing with polythene sheeting taped at the edges should also be used.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eWhen used as a surface sealer on non-trafficked cementitious surfaces, Nitobond AR is applied in two coats, the first coat diluted 1:1 with water, the second coat applied as supplied.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eTypical applications, include as a curing membrane for Fosroc Renderoc repair mortars and as a dust proofer and surface sealer for non-trafficked cementitious surfaces \u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eBenefits\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eReady to use, no mixing required\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eApply by spray, brush or medium pile roller\u003c\/li\u003e\n\u003cli class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eNon-flammable \u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp\u003e \u003c\/p\u003e\n\u003cp\u003e\u003cstrong\u003eGood to know \u003c\/strong\u003e\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003eDo not use below +3°C and falling\u003c\/li\u003e\n\u003cli\u003eWhen used as a surface sealer on non-trafficked cementitious surfaces, Nitobond AR is applied in two coats, the first coat diluted 1:1 with water, the second coat applied as supplied.\u003c\/li\u003e\n\u003cli\u003eIn fast drying conditions, supplementary curing with polythene sheeting taped at the edges should also be used.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e \u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e \u003c\/p\u003e","brand":"Fosroc","offers":[{"title":"Default Title","offer_id":57127674118476,"sku":"BM010988","price":115.42,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1046\/6715\/2716\/files\/fosroc-fosroc-nitobond-ar-1232467375.png?v=1776264622"},{"product_id":"natcem-ac-25kg","title":"Natcem AC 25kg","description":"\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003eNatcem AC is an environmentally friendly, fast-setting natural cement mortar suitable for application from a minimum of 3mm to any thickness, by trowel or pump. Formulated from a blend of natural cement binder, retarder and specially selected graded aggregates passing a 250 micron sieve, it requires only the addition of water — no primers, bonding agents or curing agents needed. Sets in 35–40 minutes at 20°C, achieves 32 MPa compressive strength at 28 days, and can be overcoated within one hour of setting. Suitable for use underwater and down to 0°C. DWI Regulation 31 approved (ref: 56\/4\/840) and WRAS approved (ref: 250155059) for contact with potable water. Supplied in 25kg bags.\u003c\/p\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eBenefits\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul class=\"[li_\u0026amp;]:mb-0 [li_\u0026amp;]:mt-1 [li_\u0026amp;]:gap-1 [\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\"\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eFast setting — commences at 35 minutes, complete at 40 minutes at 20°C\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eRapid strength gain — 4 MPa at 1 hour, 32 MPa at 28 days\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eSuitable from 3mm minimum thickness to any depth in a single application\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eNo primers, bonding agents or curing agents required — just add water\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eSulphate resistant, chloride resistant and high chemical resistance\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eWaterproof with very low shrinkage and fine surface finish\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eSets underwater and usable down to 0°C\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eDWI Reg.31 and WRAS approved for contact with potable water\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eCan be applied by trowel or pump\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"font-claude-response-body break-words whitespace-normal leading-[1.7]\"\u003e\u003cstrong\u003eGood to know\u003c\/strong\u003e\u003c\/p\u003e\n\u003cul class=\"[li_\u0026amp;]:mb-0 [li_\u0026amp;]:mt-1 [li_\u0026amp;]:gap-1 [\u0026amp;:not(:last-child)_ul]:pb-1 [\u0026amp;:not(:last-child)_ol]:pb-1 list-disc flex flex-col gap-1 pl-8 mb-3\"\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eMix ratio: 1 x 25kg bag with 5–5.5 litres of water produces approximately 15 litres of mortar\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eCoverage: approximately 3m² at 3mm depth per 25kg bag\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eDo not apply additional water during finishing — may cause surface cracking\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eOnce setting has started, do not remix or smooth the surface\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eDo not use on frozen or overheated substrates (outside 0°C–30°C range)\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eShelf life: minimum 12 months in dry storage conditions\u003c\/li\u003e\n\u003cli class=\"whitespace-normal break-words pl-2\"\u003eAlways refer to the Natcem AC Product Data Sheet before use\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"Natural Cement","offers":[{"title":"Default Title","offer_id":57431375806796,"sku":"BM06258","price":43.74,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1046\/6715\/2716\/files\/natural-cement-mortar-natcem-ac-25kg-1235054111.jpg?v=1777650393"}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/1046\/6715\/2716\/collections\/0001413_fosroc-nitobond-ep-std-25kg-2part_510_9b16ae19-506b-424b-bbe5-2ac2f8063224.png?v=1776087248","url":"https:\/\/www.constructionsuppliesuk.co.uk\/collections\/concrete-bonding-agents-primers.oembed","provider":"Construction Supplies UK","version":"1.0","type":"link"}