You need to remove any damaged or unsound portions of concrete and you need to roughen the surface of the old concrete. Although they all look the same on the surface of the slab they are used for different reasons and to achieve different results. How do You Waterproof the New Foundation Connection? Get as much of it off the concrete as you can. Bonding new concrete to plastic and hardened concrete is an important task that is needed in many construction works. Acid etching was once considered another way to prepare a surface, but experience shows that this method is not as dependable as mechanical methods (, Whatever the method, no feather edges should be permitted (, Workers can prepare the surface of construction joints during the first concrete placement. You can join the new concrete right to the old concrete, this is called a concrete construction joint. The cement within a concrete mix doesn’t contain any natural bonding agents – so when fresh concrete is added on top of an existing layer of concrete, the two won’t join together. For horizontal construction, Sometimes workers sprinkle or mix retarders into the top layer of concrete. Reinforcement (rebar or steel fibers) is placed and the concrete actually expands as it cures, resulting in tensioning of the steel. Scarifying is one of the old methods earlier used to level a floor and to prepare a concrete floor for further treatment. Drill 5/8-inch diameter holes six inches deep into the old concrete. It must be ensured throughout proper surface preparation, material choice and use, and curing. ChemCo epoxy Bonder LWL old-to-new concrete overlay Contaminants, such as oil, grease, tar, asphalt, paint, wax, curing compounds and surface impregnants, such as linseed oil, should be removed; so should dust, laitance and weak or loose concrete. Some engineers require the edges of the existing footings and foundations where the new and old concrete meet be roughened. Prepare the exposed concrete by wet sandblasting, water blasting, or shot blasting. Push the debris off the concrete surface or collect it in a bag to throw away. Epoxy resins can be formulated for different temperatures and for dry or damp surfaces. Once cured, the new concrete will simply sit on top as a separate layer. Pressurized water and air is commonly used for surface preparation. Workers can prepare the surface of construction joints during the first concrete placement. Adding a new concrete slab roof flush to an older slab can be done. Thoroughly clean the existing concrete and apply a product that bonds the new concrete to the old. concrete old new process concrete formations Prior art date 1922-02-20 Legal status (The legal status is an assumption and is not a legal conclusion. This column was shared with my 31,000 subscribers who read my March 27, 2020 AsktheBuilder Newsletter.. Actually, it will under the correct circumstances. My primary concern is I want the color and texture of the new patch to match as closely as possible to the existing driveway. The type of coarse aggregate in the existing pavement usually dictates the least costly way to prepare a surface. Simple flat roofs to sloped roofs, concrete roof tiles offered various styles and colors to meet the architectural needs. The Portland Cement Association (PCA) recommends that the surface be scarified to remove unsound concrete and cleaned by sandblasting or other means. 9902) permanently bonds new concrete, plaster, and stucco to existing concrete, plaster, and stucco. NH now requires slab on grade's to have 4' frost walls. Can you give answer to this question ? In some cases that will work >>drill rebar into the existing patio slab across the joint<< but in others because of the geology of the site, that could cause cracking around the starter bars. Shrinkage compensating concrete (Type K), with an experienced contractor and designer, can allow a reduction or elimination of joints. ACI 503 (Ref. Instead it requires a large area to be sealed off. Available in: 1 qt. Expansion Joint. The question that is coming up is in regards to the new/old concrete bond and potential moisture coming back in once were are done. Jorge ~ Reston, VA. Jorge, you have a few options when connecting an existing slab of concrete to a newly poured one. If the joint is wider than it is tall, place the holes horizontally. Explain the procedure for joining old and new concrete work, also state any two material used for filling joints. Thread starter Sumit Civil; Start date Jan 5, 2019; Sumit Civil. Bonding fresh, plastic concrete to old, hardened concrete increases the strength of the composite material. The edges of the defective area should be chipped or cut straight and at right angles to the surface, or slightly undercut to provide a key at the edge of the patch. The formation of a good bond between new and existing concrete is essential when you plan to resume the concreting of an incomplete construction member, and for other repair works. All damaged, loosened, or unbonded portions of existing concrete should be removed by chipping hammers or other mechanical methods. Prime CE. s u r face of the … Update your information about concrete roof tiles and shingles choose weather and fire resistant roofing material for your roof. This ensures a complete reaction. If possible, however, remove the old and make sure there is a solid substrate for the new concrete to rest upon that has a 4 inch thick layer of cushion sand. Connect new concrete slab to existing slab. Exceeds the performance requirements of ASTM C 1059 Type I and II. This will connect strongly when the new slab is poured. You have the right idea but may need more information before trying to attach the new to old. Regardless of the bonding medium, a minimum bond strength is required. Sweep dirt and debris off the concrete. The old concrete needs to be completely clean or else anything you pour over it won’t bond to it. Your answer. It was built in 1963 on a concrete slab with no footings or frost walls. Bob C . Slabs on grade and pavements now can be cleaned fast with high production, self-propelled cold milling equipment and improved blasting techniques. This Old House host Kevin O'Connor learns how to create concrete kitchen counters. Green concrete, 12 to 24 hours old, can be easily cut or wire brushed to create a roughened surface. Hydraulic Dredger The principal feature of all dredgers in this category is... 1. Even some require application of bonding agent to enhance the bonding. India. The edge of the existing concrete that was sawed should be drilled and doweled so the new concrete won't separate, lift, or settle from the old concrete. ACI 503 details the use and specification of epoxies for bonding fresh to hardened concrete. This is copied from a previous post. QUESTION #1: Tim, it’s time for you to reach into your magic tool bag. After surface preparation, there is usually need to apply bonding agent on the surface of the existing concrete in order to facilitate the bonding. We are about to add 896sqft off the back of the house. The US Army Corps of Engineers requires removal of at least 1/4 inch from the surface by scarification followed by high-pressure water flushing and air blowing. Steps in Construction of Reinforced Concrete Structures, Types, Assumptions and Fundamental Approaches of Structural Analysis, Overview: Open and Closed Traverses in Surveying, Engineersdaily | Free engineering database. For vertical construction. Multiple elements are used to transmit and resist external loads within a building . Make these holes 12 inches on center horizontally or vertically, depending upon the predominant orientation of the joint. Concrete Roofing- All time material - On 07/06/2012 - 17513 View(s) - 2 Comment(s) Concrete is an all time material for roofing. The chipped area should be at least 3⁄ 4 inch deep (see bottom drawing) with the edges at right angles or undercut to the surface. If the joint is taller than wide, place the holes vertically. thumb_down_alt 0 dislike. Essentially, traverse... How to Bond New Concrete to Old Concrete? Hello all, My house is 100+ years old and has a stone and mortar basement foundation. This removes any. For new floors, no special mix design is required to achieve good results. Explain the procedure for joining old and new concrete work, also state any two material used for filling joints. The feathered edges of the top drawing will break down under traffic or will weather off. 0 0. Before discussing the various methods of truss analysis , it would be appropriate to have a brief introduction. bottle 1 gallon bottle . When bonding to asphalt, the surface should be roughened so that clean aggregate is exposed. Will new concrete bond to old concrete? asked Nov 30 by anonymous. Please enable JavaScript!Bitte aktiviere JavaScript!S'il vous plaît activer JavaScript!Por favor,activa el JavaScript!antiblock.org, All damaged, loosened, or unbonded portions of existing concrete should be removed by chipping hammers or other mechanical methods. It is recommended that bonding agent is applied prior to casting the fresh concrete. Based on laboratory and field tests, the bond strength of 200 psi is generally used as a guide in designing bonding media. Scarifying creates a lot of dust and is very noisy. The first order of business is to remove gravel, leaves, sand, and dirt. Products like Sakrete Top 'N Bond and Sakrete Flo-Coat already contain polymers that greatly improve the bond of portland cement and should NEVER be used with a liquid bonding agent. Concrete cracks because it is weak in tensile strength, so when its natural tendency to shrink is restrained, tensile stresses that exceed its tensile strength occur, resulting in … Epoxy resin grouts specially formulated for each application also are on the market. However, the floor should be in place at least 28 days before polishing begins to ensure adequate curing. Bond is not, however, guaranteed. Without close attention to detail, the bond won’t be successful. The proportioning of the resin and hardener is extremely important; they must be mixed thoroughly to produce a homogenous mixture. For this reason, scarifying is not suitable when regular business has to stay open as normal. It must be ensured throughout proper surface preparation, material choice and use, and curing. The intend of the dowels are to pull together the old and new concrete together such that their bonding become inseparable. Bonding new concrete to old BY BRUCE SUPRENANT DEPARTMENT OF CIVIL ENGINEERING & MECHANICS UNIVERSITY OF SOUTH FLORIDA TAMPA, FLORIDA Figure 1. Epoxy resins and their hardeners or curing agents are co-reactants in a chemical reaction that allows the material to harden. Be sure that water used in cleaning is itself clean and also that no contaminants are present in the compressed air. Source(s): Building Contractor. I feel the best way to waterproof new foundations is to apply special waterproofing compounds to the exterior of the finished foundation. When the wet concrete surrounds the strip, you have a waterproof joint so long as the foundations do not pull apart from one another. Almost any structurally sound concrete floor, whether new or old, can be polished. Support wikiHow by Usually pro concrete workers would not set anything within the 10 width, they don't need it, but you can set something at the middle if you choose, since an 8' screed board is a killer to pull if you don't have good help. Consult your project plans to determine the spacing of the rebar that was placed in the first slab and the spacing of the rebar that is to be placed in the second slab. the pins are glued into the old slab with epoxy. Joining 2 concrete slabs [ 3 Answers ] I own a 1000 sq foot home in New Hampshire. When we place concrete there are 3 different types of joint that are commonly used, the Expansion Joint, the Control Joint and the Construction Joint. Delaying the set allows the surface to be roughened up to 48 hours after the pour. Eliminates the need for roughing the surface before the application. The most practical and economical bonding agents are sand-cement and water-cement grouts. One method is to drill old slab edge and insert steel pins. 26 views. After preparing the surface, the contractor need only decide if the, Apply the grout immediately before placing the new. The new slab would raise the main floor elevation 12" to allow for new ground works and hydronic heating and would have a 12" x 12" footing on the perimeter with 1/2" rebar dowelled in on 16" centers and be backfilled to allow for a 4" slab on top. 2) recommends that all equipment supplying compressed air be equipped with efficient oil and water traps to prevent surface contamination from the compressed air supply. POLISHING NEW FLOORS. (See below for a shopping list and tools. thumb_up_alt 0 like . It is about 7 feet from floor to joist because at some point in the past concrete footings and floor were added (the floor is lower than the footings by about 8", so I assume the footing does not extend all the way underneath the original stone foundation). Epoxy based bonding agents are very popular for such operations. After speaking to a … Background A traverse is a form of control survey used in a wide variety of engineering and property surveys. 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Most agencies specify the surface cleaning method and minimum depth of surface removal. QUIKRETE® Concrete Bonding Adhesive (No. Answered by Brett ~ May 23, 2011 ~ No Comments How will my contractor connect the new concrete slabs on the right side to the existing two slabs on the left side? Concrete expansion joints, also referred to as concrete isolation joints, are a very important part of designing and building concrete slabs. Concrete joining products work to control movement in concrete slab joints, to control and prevent the cracking within the concrete slab and to form contraction joints in concrete slabs. The chemical approach involved mixing up a liquid bonding agent that helps bond new concrete products to old. As part of our Concrete Jointing range we have products like key joints, joint systems and expansion jointing available. Measure and mark the side of the concrete where the two slabs will be joined with points where you will need to drill and epoxy splice dowels. Bonding fresh, plastic concrete to old, hardened concrete increases the strength of the composite material. 1 decade ago. Then clean it and allow it to dry thoroughly. I know in America bigger is better but it’s just not so with these products. This will not produce a strong, serviceable floor. unlocking this expert answer. But there are some exceptions. For horizontal construction joints, the top surface of fresh concrete can be roughened while still plastic. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) I need to replace a cracked-off section of my concrete driveway. Bond is not, however, guaranteed. Reaction that allows the material to harden SUPRENANT DEPARTMENT of Civil ENGINEERING & MECHANICS UNIVERSITY of SOUTH TAMPA! Depth of surface removal different reasons and to prepare a concrete construction joint own! Host Kevin O'Connor learns how to create concrete kitchen counters lot of dust and is very.. 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