No fines concrete problems cracking

How to determine if the cracks in walls are serious home. Short, thin cracks around windows are typically harmless and require no attention. However, most of these problems are avoidable, or fixable. Use proper subgrade preparation, including uniform support and proper subbase material at adequate moisture content. Wimpey nofines houses housing defects green building central. No fines concrete is literally that concrete made without fine aggregate so it has high permeability and drainage capacity.

Part 1 of this article, published in the september 20 issue of concrete international, discussed various causes of concrete cracking, industry guidance on. In the united states approximately 60% of homes are built on soils with some clay content. Common concrete problems and how to fix them ozinga blog. Cracking in concrete can be reduced significantly or eliminated by observing the following practices. Defects in concrete can often be related to the lack of durability of the concrete, resulting from the composition of the concrete, poor placement practices, poor quality control or the aggressive environment in which it is placed. Sometimes, though, cracks in walls signify a larger problem. The irregular hexagonal areas enclosed by the cracks are typically no more than 1 1. The wimpey nofines house was a construction method and series of house designs produced by the george wimpey company and intended for massproduction of social housing for families, developed under the ministry of works postworld war ii emergency factory made programme. The challenges of nontraditional housing refurbishment. Inferior mortar and concrete in the cover over reinforcing steel due to overwet concrete, loss of entrained air, inadequate curing, excessive bleeding, improper jointing and sealing, or sever map cracking poor bonding of twocourse floors due to.

The common solution to stiff concrete is to add extra water to make it more flowable. Mar 31, 2016 for those of you unfamiliar with wimpey no fines concrete, it was a method of building houses quickly with a concrete mix of just cement and course aggregate no sand hence no fines. The singlesized coarse aggregates are surrounded and held together by a thin layer of cement paste giving strength of concrete. Cracks less than 18inch wide are likely stress cracks, while larger ones are often more serious. Scarcity and corrosion of wall ties to brick cladding. Built by the wimpey company in the early 1950s, the houses are so called due to the use of cast insitu no fines concrete concrete made up of cement and graded aggregate, but no sand or other fine aggregate. You dont have to look very far to identify the real life concrete problems listed below. How to repair concrete pro tips for repairing concrete. Cracks may indicate serious structural problems and others may be insignificant. Pdf cracking is a common problem in concrete structures in reallife. Cracks in concrete holcim australia holcim australia. Cracks in a concrete patio are not just unsightly, they also invite weed growth, collect debris, and can be a trip hazard.

Concrete slabs can shrink as much as 12 inch per 100 feet. How to repair cracks in a concrete driveway the home depot. Vertical cracking has been noted to nofines concrete of external walls. Crazing is the development of a network of fine random cracks or fissures on the surface of concrete or mortar caused by shrinkage of the surface layer. No fines concrete does not pose any serious problem for compaction. If you cannot create a distinct groove, add more water.

Even the american concrete institute has no standards or recommendations that give a yes or no answer as to what cracks need repair based on width and other factors. Cracking is a common problem in concrete structures in reallife service conditions. Cracking of the rendering is another obvious danger. Knocking through wimpey no fines in situ concrete house.

Concrete can deteriorate for a variety of reasons, and concrete damage is often the result of a combination of factors. Nofines concrete is obtained by eliminating the fine material sand, from the normal concrete mix. Houses of nontraditional construction common property. The phrase no fines relates to the name of the type of concrete that was used in the construction of this system of house building. Crazing in concrete is the development of a network of fine random cracks or fissures on the surface of concrete caused by shrinkage of the surface layer. No fines concrete is obtained by eliminating the fine material sand, from the normal concrete mix. How to determine if the cracks in walls are serious hunker. Generally, it is assumed that cracks are due to some problems in the foundation, whereas it is not always correct and should not be. After all, correctly identifying pavement problems and their causes is at the heart of our business. Although this problem is not confined to high air tem. It can also minimise saturation of the storm water network, reducing the risk of flooding in heavy rain events. No fines concrete, when conventional aggregates are used, may show a density of about 1600 to 1900 kgm3, but when no fines concrete is made by using lightweight aggregate, the density may come to about 360 kgm3. It has good drainage properties due to its open texture.

However, numerous site constraints did not allow enough clearance to install geogrid reinforcement within the property limits. Plastic shrinkage cracks sometimes extending through slabs may severely damage structural concrete. Although no fines concrete has been used for paving for more than 20 years in the u. Crack patterns typically form grids of about 2inch diameters. If your cracks are accompanied by a bow or a dip in the ceiling, it is a sign of a large problem. Here are some common concrete problems to look out for and a guide on how to solve them.

Learn how to repair concrete to fix all types of concrete problems, from crack to broken corners to full section replacement. One way to repair concrete cracking is to patch the concrete using concrete fillercaulk or use a penetrating concrete sealer to prohibit any water penetration, which will minimize freezethaw damage. The weight of nofines concrete depends on the type of aggregate used. Be they straight, jagged, or spiderweblike, fine cracks in the basement floor commonly result from surface shrinkage as.

The concrete was cast in situ using reusable formwork and pretty much resembles a giant rice crispies cake slab in grey. We have no relationship with advertisers, products, or services discussed at this website. No fines houses have better thermal efficiency than many other concrete dwellings, due to the internal pore structure of the concrete. Slabongrade done wrong note the layer of granular material over the top of the plastic vapor barrier. Place the nofines concrete backfill the same way as outlined in the previous step.

Slab surface prevention repair concrete paving association of. The cracks might indicate a more serious structural problem. This is due to the evaporation of excess mixing water. If the concrete is unrestrained, no cracks will develop. Cracking can be the result of one or a combination of factors, such as drying shrinkage, thermal contraction, restraint external or internal to shortening, subgrade settlement, and applied loads. Attention to variable high and low rates of carbonation of dense aggregate concrete ring beams. These cracks are rarely more than 3mm deep, and are more noticeable on over floated or steeltroweled surfaces. They are associated with early surface drying, causing the immediate surface to shrink differently than the underlying concrete.

Before allowing the nofines concrete to cure, excess material must be brushed off the top of the block to aid in the installation of the following courses of block. However, thermal performance can still be an issue. Install the next course of blocks ensuring that they are level. Horizontal cracking of render noted above window drips. Craze cracks are very small and are found in the top surface of a slab. Diy easy big crack repair in concrete floor youtube. Wimpey no fines house insulation problem diynot forums. Several masonry patching products, such as hydraulic cement, do an adequate job of filling cracks in concrete walls.

It is important not to confuse cracks from restraint of the concrete at early ages, to plastic shrinkage cracks. Sometimes concrete has low workability or is very stiff because it has a very low watercement ratio. The joists of a home are meant to hold up to the weight of the home and remain level, but. Then i pointed out that the walkways, driveway, rv pad and garage slab also have no cracks. A neighbouring house top right has had an external render system applied to improve thermal efficiency.

Concrete floor problems building science corporation. Allan block retaining walls and nofines concrete no problem. No fines refers to the type of concrete used concrete with no fine. Defects in concrete problems and defects in hard concrete. Plastic shrinkage cracks are generally tight, about 0. The wetter or soupier the concrete mix, the greater the shrinkage will be. How to know when ceiling cracks are structural or just old. With no fines concrete the danger of dampness is remote unless there is bad detailing, or a concentration of cement grout in the wall as a result of using too wet a mix. The nofines voided concrete without sand construction technique for buildings is not particularly suited to drilling of holes to provide adequate fixings. Mar 22, 2016 the concrete is still structurally sound and is still considered a quality material. Cracks can occur when provisions to accommodate these movements are not made in design and construction. Wimpey no fines house type and external wall insulation. In some cases, one side of the crack rises higher than the other sidea condition called lippage that.

If the groove caves in, mix in more dry ingredients. Hairline cracks do not cause problems with the stability of the foundation but do cause leakage problems. Jan 10, 2018 the wimpey version had external walls formed with 200300mm thick no fines concrete poured on site into prepared shuttering containing continuous reinforcement. If the crack is horizontal or runs at a jagged 45degree angle, it might mean theres a more serious problem such as severe foundation shifting or water damage. Nofines concrete backfill is designed using 38 34 in. The thicker the subbase, the more load the slab can support, so if there are going to be heavy loads on the slablike trucks or fork liftsthe designer will probably specify a thick subbase. Nofines concrete is a nonproprietary material used widely in england and scotland for the construction of walls in dwellings. Similarly, my neighbors concrete patio has no cracks either. The most widespread applications of no fines concrete include road paving, and surface treatments to permit water drainage. It might be best to give the steel a bit of a rub, and coat with a rust proofer from halfords, or a. This helps the repair material to key into the crack, creating a mechanical bond in addition to the chemical bond between the patch material and the concrete. If the surface remains smooth and the sides of the groove hold their shape, your concrete is ready.

Most wall cracks can be remedied by retaping drywall joints. An extensive survey carried out revealed that concrete cracking can be attributed to the following. No fines concrete is literally thatconcrete made without fine aggregate so it has high permeability and drainage capacity. This article describes the types of cracks that occur in poured concrete slabs or floors and explains the risks associated with each, thus assisting in deciding. Cip 4 cracking concrete surfaces what are some forms of cracks.

The total shrinkage of nofines concrete on drying is. The synthetic fibers eleminate the need for wire mesh in slabongrade construction. These particular units had long term problems of rain penetration at roof level and defective render. Then i went the easy route and got the premixed concrete mix sealer. No fines concrete, also known as porous, pervious, permeable and cellular concrete, is a porous concrete obtained when fine aggregate is omitted. Crazing, a network pattern of fine cracks that do not penetrate much below the surface, is caused by minor surface shrinkage concrete slab surface defects. Constructed from cast insitu concrete, no fines was one of the most successful system built houses. When you learn how to repair cracks in a concrete driveway, you may be able to stop them before they lead to bigger problems. Shifting soil and freezethaw events turn small cracks into wider and longer cracks. As the concrete hardens and starts to lose the excess water, shrinkage begins. If there is no associated cracking to the walls inside or out, then this corrosion is not normally a problem and is just due to internal humidity penetrating the plaster. The irregular hexagonal areas enclosed by the cracks are typically no more than. No fines refers to the type of concrete used concrete with no fine aggregates.

Stairstep cracks that start at the corners of windows. Below we have identified and pictured specific distressesfailures any pavement contractor should be able to identify. A subbase can also act as a capillary break, preventing water from wicking up from the. The wimpey no fines house was a construction method and series of house designs produced by the george wimpey company and intended for massproduction of social housing for families, developed under the ministry of works post world war ii emergency factory made programme. Dryingshrinkage cracks like these often result from improper joint spacing.

How concerned you should be about cracks in the walls. How to solve common concrete problems in construction. Cracking of the re n d e r ing is another obvious danger. A subbase and base course, or both, provide several good things. How to minimize cracking and increase strength of slabs on grade. These cracks are rarely more than 1 8 inch 3 mm deep and are more noticeable on steeltroweled surfaces. They are either in conduit which is fine for the lights, except the conduit box is near the window. New homes cracks that occur in the first few months or years. The cracking phenomenon when placed concrete typically contains more water than is required for hydration of the cement. Extensive cracks which get longer and wider in the concrete slab are also no good, and might even cause parts of the concrete slab to heave, become uneven or collapse. Use of mechanical compaction or vibratory methods are not required. A major cracking problem that joint control will not solve, plastic cracking also. Also, rapid drying of the slab will significantly increase the possibility of cracking.

Cracking, shrinkage, low strength and high porosity often result. Crazing, a network pattern of fine cracks that do not penetrate much below the. No fines concrete is a lightweight concrete made up of only coarse aggregate, cement and water by omitting fines sand or fine aggregates from normal concrete. Founded in 1904 and headquartered in farmington hills, michigan, usa, the american concrete institute is a leading authority and resource worldwide for the development, dissemination, and adoption of its consensusbased standards, technical resources, educational programs, and proven expertise for individuals and organizations involved in concrete design.

Concrete problem and causes concrete is an excellent material, but it is not perfect. In most cases where cracks appear in concrete the crack can be identified and the cause of cracking established. This shrinkage causes forces in the concrete which literally pull the slab. When a garage floor is first poured, the concrete begins to harden contractors say cure and when this process takes place the concrete shrinks a little. Inspect the position of the crack after measuring its width. Because of the low hydrostatic pressure, no fines concrete permits the use of very large, lightweight forms. Overworking causes aggregate to settle and bleed water and excess fines to rise. Cip 3 crazing concrete surfaces why do concrete surfaces craze. It might be best to give the steel a bit of a rub, and coat with a rust proofer from halfords, or a bit of hammerite or similar paint.

Cracking unexpected cracking of concrete is a frequent cause of complaints. Wimpey nofines houses housing defects green building. No fines concrete, as the name implies, is simply a concrete product that doesnt contain sand or fine materials. The wimpey version had external walls formed with 200300mm thick no fines concrete poured on site into prepared shuttering containing continuous reinforcement. Foundations crack for many reasons including unstable soils, poor drainage and settling. If the cracks appear shortly after pouring the concrete foundation, concrete may have been mixed poorly or poured too quickly. Alligator cracking is a load associated structural failure. A crack is a linear fracture in concrete which extends partly or. In general, howe ve r, the nofines mix will be only about twothirds of the weight of a dense c o n c r ete made with the same aggre g a t e. Use the back of a shovel to create a smooth surface, then use the side of the shovel to create a groove. Wimpey no fines house type and external wall insulation sps. The density of this product will vary with the density of the aggregate used, but will typically range between 100 lbft.

Liquid phase water will be held by the fines in the granular material creating a reservoir of water that can only dry upwards into the slab leading to problems with floor finishes and floor coverings. Boral no fines permeable concrete, when placed correctly, absorbs rainwater and facilitates natural runoff into the ground or storage tanks. This form of lightweight concrete is generally a crushed rock or gravel of 20 mm single size aggregate 1020 coated in a cement slurry with no fine aggregate addition. In poured concrete foundations, hairline crack frequently appear in the center of the walls because the wall. Evaluation of shrinkagecracking characteristics of structural. Advantages, limitations and mix proportions of no fines concrete is discussed. Very often only single sized coarse aggregate, of size passing through 20 mm retained on 10mm is used. Repeated freezing and thawing, heavy loads, tree roots and even shifts in the ground can cause damage. The secret to fixing wide concrete cracks is to undercut the sides of the crack to give it an inverted v shape. In general, cracks wider than a credit card and running through the depth of the concrete are structural in nature and could be a sign of more serious problems see concrete. So the walls are basically a solid mass of grey concrete full of pebbles like a giant rice crispies cake. Then i filled the deep cracks with cheap fine grain sand to make sure it was full all the way down deep. Concrete not exposed to weather or in contact with ground. Cracking, spalling, scaling, honeycombing, settlement, alkali aggregate reactions, piping, loss of binding paste.