Tuesday 24 October 2017

Ordering Concrete? Tips to Build It Right

mounir LT October 24, 2017 Ordering Concrete , 0 Comments

Ordering Concrete? Tips to Build It Right

Whether your concrete need is as small as needed for fixing cracks and holes in the wall, building a patio, paving, pathway, or as large as a construction of a high-storey commercial building, the first step to begin is by ordering the exact volume of concrete needed. It comes as the next point that how the ordered concrete should be delivered to your work site. While most projects are measured in square feet, when you place an order for concrete, it is done in cubic yards. Measure the dimensions of the site to determine the right volume of concrete needed.

First you need to multiply the length of the project by width, then multiply the resultant figure by depth (meaning thickness), and divide it by 27 to learn the amount of concrete needed in 'cubic yards' unit. Finding it difficult to calculate on own? There are many websites featuring online concrete calculator. Or you can always contact your local concrete supplier company so that a concrete specialist can visit the site in person and help you determine the right amount of concrete mix needed for your project; this approach will help you avoid under-ordering and over-ordering scenarios. Many concrete suppliers offer on-site assistance right from determining the needed volume, onsite concrete mixing and application to refurbishment of the concrete structures. Now when you know how much concrete you will need, the very next step is to decide how to get the job done. Concrete as we all know is a blend of Portland cement, sand, gravel and water. Other aggregates can be added by the supplier company depending on your project specifications.

Why Choose Ready Mix Concrete For All Your Construction Needs

Now, before sharing the 12 time-tested tips to succeed in your construction project, it is worth mentioning here that ordering ready mix concrete London is far better than mixing concrete onsite. Even if you pay a bit more ready mix which is also called ready to lay concrete, it's pool of advantages such as no need of storage space, instant application, faster construction, reduced need of workforce, top-quality and sustainability make it a smarter alternative. Moreover, the concrete supplier companies are catering to any small and large size order of ready mix concrete. So, both DIY residents and contractors can leverage from its many benefits. Simply put, ready to use concrete reduces the work on site, improves the quality and finish of work, and fast-track the project accomplishing.

Top 8 Tips To Prevent Failure In Your Construction Project

Don't order less than what you need
Cover concrete using plastic or damp fabric to avoid cracks
Add colour and additive straighten; or you can reduce curing period
Concrete mix may need reinforcement of steel bars, wire mesh, etc. to boost strength; consult a concrete specialist to learn more.
For DIY project, use safety wear to protect eyes, nose and skin from any harmful effects
Adding more amount of Portland cement can increase the strength of the concrete mix
If you will need concrete during Christmas or in holiday season, check if the supplier you choose are open during the festive season or not; if yes, it is recommended to schedule delivery in advance. Planning advance will avoid extra charges and all hassles.
If you will need concrete pumps to transport concrete mix on the site, plan ahead and hire concrete pumps while ordering the mix

Hope these tips will help you order concrete mix the right way!

Article Source: Ordering Concrete? Tips to Build It Right

Tips to Cure Concrete in Winter

mounir LT October 24, 2017 Tips to Cure Concrete in Winter , 0 Comments

Tips to Cure Concrete in Winter

In cold weather, if you want to cure concrete, you should have the required material and knowledge. Water, humidity, temperature and even snow are factors that can complicate cold weather concreting. You should never pour concrete on frozen ground and must be very cautious when temperatures fall below the freezing point. Concrete hydration can also be affected as soon as the temperature falls below the freezing point. Read on to know our tips to cure concrete in the cold season.

Required materials

You may need different materials based on the quantity of concrete that needs to be cured as well as the surfaces that need to be protected. Certain materials may produce or even increase heat. These materials include chemicals, windbreaks, insulating blankets, electric heated blankets, straw-plastic and insulating sheets.

Know the facts

When placing concrete in cold weather, there are two major factors you will want to concern yourself with before starting your project:

#1 - When it is cold, concrete sets more slowly - slow at 50°F, and when it's below 40°F the hydration reaction will basically stop and the concrete curing process halts. Ideal temperature for curing concrete is about 80 degrees F.

#2 - Concrete may freeze before gaining enough strength which will break up the matrix of the concrete and weaken your overall finished product. You don't want this.

There is a difference between concrete temperature and air temperature. When it's cold outside, the concrete will need to be protected until it can handle the cold on its own. Rule of thumb #1 is that once the concrete has strengthened to 500 psi then it's safe. The important thing that happens at this point is that at almost the same time that the concrete hits 500 psi compressive strength, there's not enough water left in the pores to damage the concrete, or in other words, hydration of the cement has consumed enough water in the mix so that freezing won't affect it much. With almost all concrete, this will happen during the second day, even at 50° F.

There are usually two things we can do in cold weather to help achieve the required number of 500 psi strength which will help you get the best results and the best finished product:

Change the mix of your concrete to get it to set more quickly
Protect the concrete from the cold using blankets, tarps or tenting
or preferably - both.

First, you should make sure that the water to cement ratio is appropriate. When the temperature is below the freezing point, this ratio should not cross 0.40.

In too cold conditions, you can use a polyethylene enclosure, heated concrete curing blanket or propane heater to maintain the temperature.

You should use a type of cement that will not reduce the quality of concrete. This is because too much moisture can cause corrosion.

You can use furnace slag, silica fume or fly ash to control the ions of chloride.

You should let the forms stay put for as long as you can. The edges and corners are more vulnerable. Moreover, forms can help you with the process of heat emission.

It's not a good idea to remove the blankets in winter because this can cause temperature differences in the concrete.

You can cure concrete below the surface of water as well. The product contains a tiny amount of high quality fine aggregates, such as sand. Moreover, additives are also put into it and they don't let water get into the surface of concrete. Usually, this product is used to make pavements because it won't absorb water.

You should hang on until all of the water gets evaporated. In winter, concrete takes a while to cure. So, the bleeding will take some time to stop. So, you may want to be ready to deal with more of it.

During this process, make sure you use a quality infrared temperature measurement gun to note down the temperature of concrete.

For choosing the insulation, make sure you know the air temperature, cement content and the thickness of the concrete.

You may want to apply some concrete sealant to seal the concrete. This is to prevent water from getting into the concrete. Aside from this, the sealants will increase the life of the concrete and will cut down on the chances of failure. In cold states, you may want to use only a type of concrete that can breathe. The reason is that it lets water and moisture evaporate in order to let the concrete set.

Article Source: Tips to Cure Concrete in Winter

Achieve Better Results With Concrete Stain By Using Concrete Stain Prep

mounir LT October 24, 2017 Concrete Stain , 0 Comments

Achieve Better Results With Concrete Stain By Using Concrete Stain Prep

Concrete stain which was once a specialty flooring product and found primarily in commercial applications has quickly become a residential product as well. Now found in many homes and gaining popularity, it has become today's alternative to traditional flooring, being used both indoors and outdoors. Though it was once available only to contractor's, the increased demand for concrete stain from the do it yourself population has brought the product into the mainstream.

Concrete stain promises to give beautiful results while being very simple to use. The cost savings as compared to other flooring products is substantial, and the extremely low maintenance of concrete "acid stain" is being enjoyed by all who have it. It tends to marbleize the concrete when used on smooth concrete and gives it more of a stone appearance when used on rougher concrete. It also has many other uses, such as garden statuary, retaining walls, water features, and more.

Along with homes and many commercial applications, such as restaurants and malls, anyone who has been to an amusement park has seen concrete stain. The boulders, waterfalls, and cave walls are usually made of concrete and then stained. Concrete Camouflage® says that certain major cities have began to use their concrete acid stain for curbing and cross walks. This a great idea. Once the other states and cities catch on to this, you'll finally start to see much less peeling paint.

Concrete stain can be sprayed on, brushed on, and some stains are rolled on. It can be sealed and/or waxed, or just left in a natural flat state. However, as great as concrete stain is, anyone that has seen and recognized very much concrete stain has inevitably seen a bad job as well. One that has spots, blemishes, or patches of trouble areas.

Many blemishes and even hairline cracks are usually considered character and are actually desired to some extent, for the added character and uniqueness. Although the obvious "job gone wrong" blemishes are not at all desired and can ruin an otherwise beautiful project. So you have to ask yourself, if concrete stain is so simple, then why and where are these bad jobs coming from? Well, that's easy. Incorrectly cleaning and preparing the concrete to be stained, is definitely the primary cause, hence the creation of Concrete Stain Prep TM.

When staining concrete, or when applying any decorative concrete product for that matter, cleaning and preparing the concrete is all important. If the concrete has not been adequately cleaned and prepared, then inferior results will ensue. If you were to look at concrete under a microscope you would see that it looks like a sponge. Though it appears to be a smooth surface to the eye, it is actually very porous. The need to clean the surface is obvious and fairly easy, it's what stays trapped in the pores that will work against you. This is the piece of the puzzle that makes the difference.

"Concrete acid stain" which is by far the best concrete staining product, works by penetrating the concrete surface and pores, and reacting chemically with the cement and minerals within. Thereby permanently changing the surface color, it tends to mottle and give you the darks and lights, highs and lows, naturally. Obtaining the marble or stone look.

"Acrylic concrete stain" or other types of topical stains, which are similar to paints, come in solid colors, transparent, or semi transparent and still needs as clean of a surface with as clean of pores as they can get, to grab on. Without clean pores, no type of stain can work or perform as well.

Even when staining new concrete, oils, glues, curing agents, and other undesirables can be found. Many times you do not even realize that they are present, until after you have stained the concrete. Then you definitely know where your oils, paints, and trouble spots are, because acid stain simply will not take as well in those areas or spots, if at all. And acrylic stain or topical stains will not stick as well as they need to, leading to premature failure. Trouble spots can be caused by many different foreign substances, and once you've stained the concrete, it's a little late to go back to the cleaning stage.

Some suggest acid washing the concrete first, however, acid washing the surface greatly diminishes the effects of concrete stain and should definitely be stayed away from, along with cleaners that contain heavy alkali's. And besides, acid washing will simply not work on many substances. Especially if your dealing with an older floor or one that has been covered in glues, paints, or muck.

That's why Concrete Stain Prep TM was developed. The latest product by Concrete Camouflage®, it is sure to revolutionize the concrete stain industry. Concrete Stain Prep TM is a biodegradable concentrate formula that you mix with water, and that replaces the need for multiple cleaning and stripping products. It deep cleans the concrete. Getting into the pores and lifting oils, dirt, and grime, as well as stripping contaminants. It leaves the concrete and it's pores squeaky clean and ready to stain. Finally you can clean and prepare concrete adequately, easily, and economically. Though formulated to mix with water, you can also use Concrete Stain Prep TM straight if needed, but beware, it will soften or melt rubber tires when used straight. If that doesn't remove whatever is plaguing your concrete and standing in the way of a beautiful stain job, then nothing will.

So whether you're an artist, a professional contractor, a do it yourself enthusiast, or someone who teaches people how to stain concrete. If you decide to clean, stain, or decorate your concrete, you should try Concrete Stain Prep TM. You're sure to enjoy better results and easier cleaning, as you more successfully Camouflage Your Concrete! TM.

Article Copyright 2006 David S. King, freelance writer. / Concrete Camouflage®, Camouflage Your Concrete! TM, and Concrete Stain Prep TM are Registered and non registered trademarks of the Camouflaged Concrete Corp. All rights reserved.

Article Source: Achieve Better Results With Concrete Stain By Using Concrete Stain Prep

Concrete - What to Do About Dusting, Crumbling, Cracks and Discolouration

mounir LT October 24, 2017 Cracks and Discolouration , Crumbling 0 Comments

Concrete - What to Do About Dusting, Crumbling, Cracks and Discolouration

Concrete is one of the most common materials used in modern construction; the reason for this is that there is no other material that can provide the same results as concrete. The use of concrete for construction provides some great advantages, such as ease of use and strength. When concrete is in it's liquid form it is very easy to use, but when it dries it provides incredible strength that will last for years. Despite the fact that concrete is a great source of construction material for everything from concrete floors, to building foundations, bridges and tunnels, there could be some problems with the concrete over time. Some issues that may arise include the overall strength of the concrete itself, as well as corrosion due to the concrete being exposed to excessive moisture; in addition, the surrounding soil composition could also cause some problems. Not only could low quality materials and improperly mixed concrete be costly later, but it can also be dangerous if the result diminishes the concrete's strength. To avoid these problems it is advisable to always use high quality concrete and to stay vigilant for possible problems with the concrete.Some of the most common concrete problems include,

Dusting: The surface of the concrete will form a loose powder, which indicates that the surface of the concrete is disintegrating. This can be caused by water bleeding into the concrete during finishing. This may cause the concrete to have a high water ratio, leading to a weakened surface. Additional causes of this concrete problem may include using heaters during a cold weather operation without adequate ventilation, which may cause excessive carbon dioxide, leading to carbonization, or allowing the surface of the concrete to freeze.
Flaking & Peeling: The freezing and thawing process of finished concrete often causes flaking and peeling; some of the factors that may contribute to this problem include, not using air-entrained concrete, which is a must to protect the concrete from the affects of freezing and thawing. In addition, if there was too much calcium chloride used as an accelerator, this may also cause a problem with peeling and flaking. Some other situations that may cause concrete to flake and peel include working the surface of the concrete too much, insufficient curing, water bleed, or using deicer.
Fine Cracks in the Surface of the Concrete: In some cases the surface layer of concrete may begin to form a network of fine cracks. This problem is often caused when a rapid drying procedure was used, or there was inadequate curing of the concrete. Other contributing factors may include water on the surface during finishing, or the sprinkling of cement on the surface in order to dry the water bleed.
Cracking: The most common reason that concrete cracks is due to the expansion and contraction of the concrete without s sufficient means of relieving stress. This could be the result of improper jointing, shrinkage, and settlement. Other contributors to this problem include freezing and thawing, or external restraint, such as flooring.
Shrinkage: Another common problem with concrete is cracking due to shrinkage. This may occur when there is a rapid evaporation of the surface before the concrete has set.
Reduced Strength of Concrete: This can happen when improper casting, handling and curing procedures are used; additional causes may include high air content, too much water, or an error in the manufacturing of the concrete.
Delamination: This is a situation where there is a separation between the top slab and bottom slab that may be caused by a thin layer of water or air. Some situations that may lead to this problem include when air entrained concrete is used for hard finishes, sealing the surface while there is still bleed water present, overworking the surface, or using a polyethylene vapor barrier.
Discoloration: Some of the most common causes of concrete discoloration include using calcium chloride to speed set times, changes in the mix proportions or material sources, uneven curing.
Curling: When curling occurs, essentially what happens is that there is a distortion of the flat surface into a curved shape. This is frequently the result of a difference in the temperature of the moisture content between the top and bottom of the slab.
Uneven or Spotty Setting of Concrete: The most common cause of this problem is not mixing the concrete thoroughly, and the use of some superplasticizers with normal setting or retarding admixtures.

Many of these common concrete problems can be avoided when the proper procedures and materials are used during construction. Concrete admixtures can help to ensure a perfect concrete finish, if they are used correctly. This is why you should always purchase your products from an experienced construction chemicals supplier. Concrete sealant is an important aspect of preserving a concrete finish. These sealants are designed to inhibit liquids from being absorbed by concrete. In addition, this will also help protect the concrete from water erosion or freezing, as well as from substances such as salts and acids. Making mistakes when laying concrete can be very costly; to avoid the added expense of having to repair the concrete at a later time, you should always ensure that you use the best concrete products available, and that you follow the proper procedure for laying concrete.

Article Source: Concrete - What to Do About Dusting, Crumbling, Cracks and Discolouration

Concrete Countertops - Stamped, Stained, Polished and Colored

mounir LT October 24, 2017 Concrete Countertops - Stamped , Polished and Colored 0 Comments

Concrete Countertops - Stamped, Stained, Polished and Colored

Concrete can be used in copious applications using a variety of techniques. It is durable enough to last for decades to come, strong enough to be used in structural applications, and malleable (before cured) to be molded to almost any form or shape. It can be used in flooring, wall, and ceiling applications, or it can be employed to construct statues and furniture. It can be made to look industrial and cold as well as traditional and warm. With so many applications, it is nearly safe to say that concrete can be used to make almost anything, and countertops are no exception.

Concrete countertops made their debut into restaurants, retail establishments, and homes over a decade ago; however, they have grown to be more accepted in the last few years. Once a countertop material for only the do-it-yourselfers and the exceptionally rich, concrete countertops are now starting to make their way into mid-priced homes and common commercial applications.

Utilizing concrete countertops has become an increasingly popular way for designers and homeowners to achieve a look unparalleled by any other material. Concrete countertops can add the perfect design element to almost any design style, including traditional, earthy, modern, industrial, contemporary, and more. Concrete countertops are only limited to the imagination and the ability to make the forms as such.

Key Components that Effect the Look of Concrete Countertops

Aggregates.

All concrete requires coarse and fine aggregates for proper consistency and strength. In fact, these aggregates are a main composition of concrete. In the application of countertops, the aggregates are of great importance. Obviously, the aggregates must allow the concrete to set up as it should. However, aggregates can have roles in the aesthetics of the concrete countertop, as well. For example, the type of fine aggregates chosen (i.e. sand) can drastically change the color of the finished product. Also, if the countertop is polished, the process can grind into the concrete, exposing aggregates. In this case, aggregate sizes and colors are just as important as any concrete coloring to the final look of the top. Also, if exposing the aggregate, consider using aggregates other than gravel, including broken glass, marble or granite chips, nuts and bolts, etc.

Portland Cement.

Portland cement is the binder that keeps concrete held together. Because traditional Portland cement is grey in color, it can have an effect on the overall look of the concrete countertop. If you are looking for a top that can be easily stained dark colors, or if you are wanting to leave the concrete countertops the natural, grey color, then regular Portland is the right choice for the project. However, if your concrete countertop is going to be white or light colors, or you need it to be easily dyed or stained, you may be better suited to choose a white Portland cement. It has the same binding properties as traditional Portland, only it is white in color when cured. White Portland is the only way to get a truly white concrete countertop.

Colors.

There are a variety of techniques used to achieve a certain color in a concrete countertop. One of the most basic methods is adding a pigment into the concrete mix before the countertop is poured. These colors are often called integral colors or integrated colors. Integral colors add color throughout the countertop, making the center of the countertop the same color as the surface. This is especially important if any grinding or polishing is to occur after the pour. Post-pour colors will grind off, exposing the original color of the concrete. Some post-pour concrete coloring techniques include stained concrete countertops, tinted concrete countertops, and dyed concrete countertops. Each coloring method will result in a uniquely different result. Generally, the same rules apply for concrete countertop pre- and post-pour coloring techniques as they do for regular concrete slabs. Make sure to check rules and tips for each of these techniques before attempting. For example, you will likely want to wait until the concrete countertop is completely cured before applying any stain, which may take up to 60 days for interior applications.

Sealers.

For every concrete countertop, you will want to use some sort of sealer. Concrete is naturally porous, so you will need a sealer to keep the pores from sucking in bacteria, stains, etc. There are many different sealers. Because this sealer will protect your concrete countertop investment, don't cheap out on this step. Especially for kitchen applications, choose an FDA approved sealer. There are also some that are less hassle than others, so pay attention to details like application procedures and length between reapplying. Sealers can come in many different sheens and even tints. A higher gloss sealer tends to bring out the richness of the colors, while a flat or matte sealer will tone the concrete countertop down a bit. Tinted sealer must be used carefully because if the color is conflicting or if the particle count of the tint is too high, it can completely ruin the hard work you put into the concrete countertop.

Decorative Props.

Concrete countertop fabricators have been trying many unique ways to set their countertops apart. One semi-common technique is inlaying decorative materials into the concrete countertop when the concrete has yet to cure. Inlaid materials can include sea shells, tiles, natural stones, glass, etc. Even more delicate objects like preserved leaves can be inlaid. Although a sealer can add some protection, always consider the long-term durability of the materials you choose to inlay in the countertop. Countertop artists have also been playing with objects to impress into the concrete. If used on a functional countertop, impressions should be shallow to avoid creating an area that collects dirt and grime. Impression materials are abundant and can include rubber stamps, hand or foot prints, leaves and sticks, cookie cutters or cake molds, etc.

Surface Finishes.

For the surface, there are many different finishes that you can choose, including flat, polished, stamped or impressed, troweled, textured, and more. This finish can have a enormous impact on the final look of the concrete countertop.

Edge Shape.

If you can imagine an edge finish, it is available with concrete countertops. The only limitation is the maker's ability to create the mold or form. Of course, square corners are an easy and common edge shape for concrete countertops. Also, you can use a router, like those used on granite or marble countertops, to create edge styles including bull nose, rounded corners, triple egg, ogee, and more. There are also a variety of Styrofoam and rubber edge molds that can mimic wood trim, jagged rock edge, and numerous more. Or, if you are feeling adventurous, you can create your own molds. Just remember: you only get one try. If you mess up, the only fix is a new concrete countertop.

Sinks.

If you are really going for a streamline look with your countertop, consider actually molding your sink into the concrete countertop. This will mean you have one fluid piece that accounts for the counters and the sink with no seams. There are even more sink shapes available with concrete than there are with other materials. Again, if you can dream it and build the mold, you can make it with concrete.

Article Source: Concrete Countertops - Stamped, Stained, Polished and Colored

DIY Concrete Mixing - Advanced Mix Ingredients & Techniques

mounir LT October 24, 2017 Concrete Mixing , 0 Comments

DIY Concrete Mixing - Advanced Mix Ingredients & Techniques

Once you have established a basic understanding of a simple concrete mix you can begin to learn more about new concrete technologies and the true limitations of this incredible building material - hint, there are not many!

By changing the volume and type of aggregates that you use in your cement mix you can create many different types of concrete suited to different applications. In general the goal of substituting aggregates is to have the concrete remain consistently strong as a finished product. Some examples of concrete advanced techniques are:

1) Color or dye in the concrete
2) Lightweight concrete
3) High strength concrete
4) Decorative concrete

Even all of these options are just the tip of the iceberg for what concrete is capable of. The extreme limitations of current concrete technology being researched and developed are transparent (translucent actually) concrete which will show a silhouette through concrete that is meters thick! Limitations of concrete strength is self supporting concrete which does not require the mechanical assistance of steel grid work. Concrete strength used to be measure is PSI however mPa or mega Pascals is the current unit of compressive concrete strength referring to the amount of force the concrete can ensure before failure.

Coloured Concrete
You can add powder or liquid pigments to your concrete to achieve interesting and dynamic colors. Common colors would be brown, red, dark grey, tan and other similar earth tones. To get more vibrant concrete colors you can use pure white Portland cement in place of regular cement, as well as pure white sand instead of regular sand. This white mortar mix will react well to more vibrant colors and pigments. The amount of pigment or dye that you use will depend entirely on the brand that you choose. The best method is to purchase from a specialty concrete supply store which will have a far better selection of quality concrete color additives than your local hardware supply store.

Lightweight Concrete
You can replace all or part of the sand in a 3:1 mortar mix with aggregate materials that are much lighter in nature than sand. The result will be a concrete that is much lighter, but also vastly weaker than a 3:1 sand mortar. There are many applications for lightweight concrete with many of them being decorative such as planter pots or garden statues. The most common lightweight aggregate material substitutions for making concrete are:

Vermiculite - which is a mineral and often sold as "pool base" in larger quantities from pool stores which will make a relatively strong, but compressible concrete. The insulation value of vermiculite is very high, more than ten times as high as sand, so vermiculite concrete mixes are often used for sound dampening and insulating.

Peat Moss - Using peat partially in place of sand will result in a concrete that is much weaker than traditional 3:1 mortar and even much weaker than vermiculite concrete. The texture of the concrete is somewhat earthy and finishing and detail work con be slightly difficult by comparison with other mixes.

Saw Dust - This is another readily available and cheap aggregate substitutions used to achieve a lightweight concrete. In addition to providing a rough and inconsistent texture to the concrete, the wood ingrained will often stain and discolour creating an interesting and unique pattern. Too much sawdust can make the concrete unacceptably weak very quickly - more so than vermiculite and peat moss.

Perlite - This is commonly used for gardening and is recognisable in that it is completely white and very similar in texture to styrofoam beads. The main advantage of this aggregate choice is the fact that it is white. It has a similar overall feel as vermiculite however the concrete produced with vermiculite is much easier to work and finish than concrete made with perlite.

Usually you can replace up to two of your three buckets of sand with an alternative aggregate. Vermiculite can be mixed with straight cement without sand and still remain strong enough to suit several tasks such as swimming pool floors. The other aggregates will yield a concrete that will break under its own weight.

High Strength Concrete
The current strength for concrete is measured in mPa with the average sidewalk concrete being 10-15 mPa where as foundations for homes usually start at 20-25 mPa. High rise commercial concrete is closer to 35 mPa as is swimming pool construction concrete.

The strengthening of concrete over and above what a 3:1 mortar mix will yield requires engineering and testing. If you order concrete from a ready mix or bath plant you can specify precisely how strong you want the concrete to be. If you are mixing it yourself and want to make the concrete as strong as reasonably possible there are a few things that you can do.

Glass Fibres - Glass fibres and fibreglass are two different additives which you can put into your concrete to help make it cohesively stronger as well as minimize hairline cracking in the concrete during the curing process.

Water Reducer - is a liquid that you can put into the concrete in place of water. The water reducer will increase the viscosity and workability of the cement dramatically without affecting the finished strength negatively. The more water that you put in concrete the weaker the finished product will be. In place of water reducer you can also use the absolute minimum water possible to get the concrete workable to make it as strong as possible.

Powder Additives - Combinations of highly dense powders such as silica fume and fly ash can potentially help to make concrete stronger by filling in some of the microscopic spaces left in regular concrete by the larger sized aggregates. These tiny aggregates are dangerous to work with because the airborne particles are small enough to damage your lungs should you breathe them. Most of these powder additives will be hard to locate for the average DIY enthusiast.

Decorative Concrete
In place of sand you can also add just about any other substance such as glass or coloured beads, pieces of plastic or metal, rubber or anything else you can think of. Most commonly you would use this concrete to create an exposed aggregate where loose aggregate is imbedded into the top of partially cured concrete. Exposed aggregate with small coloured stones is very common and you likely have seen this before. Exposed aggregate with marbles and microchips is less common to be sure - but not any less possible.

With some basic practice you can learn to create incredible things such as statues, pool decks, artificial rocks, ponds, waterfalls and decorative art.

Article Source: DIY Concrete Mixing - Advanced Mix Ingredients & Techniques

Recycled Concrete Aggregate and the Need for Sustainability

mounir LT October 24, 2017 Recycled Concrete , 0 Comments

Recycled Concrete Aggregate and the Need for Sustainability

The interest of including sustainable development in construction is on the rise due to the changing systems of the world based on its economy, its environment and society. The most immediate and obvious way to achieve more sustainable construction today is by conserving new raw materials such as natural aggregates, and reusing construction and industrial wastes. For those who may not know, recycled concrete aggregate, better known as RCA, is an example of a common construction waste that is produced after demolishing concrete structures. Supplementary cementing materials (SCM) such as fly ash and slag are industrial by-products, which have a long history of use with Portland cement (PC) in concrete. Although Portland cement is the primary source used for construction, it has been found that it is no longer feasible and the continuation of its usage will no longer supply benefits in cost management and will further deteriorate the environment, consequentially impacting global society. The study of recycled concrete aggregate is interesting because it is a new mechanism used that could potentially impact society as a whole, economically, environmentally and socially. The aim of this article is to examine and provide an analysis of the technology used when recycling concrete aggregate, instead of using virgin aggregate, as is the current procedure in Canada.

Due to the high urbanization of many cities in Canada, concrete is one of the most popular construction materials used in the country. Environment Canada has identified that two thirds of the concrete's production is used in basement's foundations for commercial and residential constructions. The basic components that produce concrete are aggregates, cement, water and some chemical admixtures. Concrete consists of 75% of the weight of all construction materials. Interestingly, construction and demolition waste in Canada amounts to 15-20% of all landfill materials. Due to the increase in waste in general, there needs to be a mechanism in places where waste can be reduced and one place is within the process of recycled concrete aggregate. By finding new applications for concrete waste, and creating a market for its use, we can bypass the need to consume virgin natural aggregate and simultaneously conserve landfill space.

So far, RCA has been used based on a granular base, mixed with natural aggregate in concrete applications used for roads. Research has shown that the use of 30% RCA and 70% natural aggregate in high strength concrete produces concrete of similar strength as that containing only natural aggregate. Although the strength of RCA is similar, the concern is the shrinkage that occurs during the drying of RCA in concrete. New concrete made with RCA experiences creep and drying shrinkage that is 10- 30% greater than that of concrete made from natural aggregate. It has been found that the porosity level in RCA increases the levels of shrinkage when it is in the drying process. Furthermore, RCA is also known to have lower elastic modulus than natural aggregate, which also contributes to drying shrinkage and creep. Although these negative impacts occur, this does not mean that RCA cannot be used entirely.

Previous to the notion of use recycled concrete aggregate, blended Portland cement (type I (SM) ASTM or CEM II-M), river siliceous sand, and granitic crushed stone (nominal size 6-20 mm) were used to make the concretes. Now, as a result of virgin concrete shortage, there is a use of not only RCA but recycled fine aggregate (RFA). For recycled concretes, recycled fine aggregate (RFA) is taken from crushed waste concretes of varying qualities, and made with granitic stone, and is used by replacing its contents (0%, 20%, and 30% by volume) of natural sand. In all concretes, an admixture acting as a water-reducer is used. The physical properties consist of either coarse and fine aggregates, they are determined by their fineness, gravity (saturated and surface dry - SGssd), water absorption, and material finer than 75 lm.

Many countries have begun discovering the use of RCA but RFA has been found to be just as workable and each RCA and RFA have their benefits in varying industries. Several countries have recommendations for the use of recycled coarse aggregates in structural concretes, but the recycled fine aggregates (RFA) are discarded because they may produce modifications on the fresh and hardened concrete properties. It is not only the use of RCA that can reduce waste and help benefit the environment and the economy, but RFA is a precious material and has become more important in concrete production because of economic implications related to the shortage of natural sands suitable for that, and the need for a comprehensive utilization of such wastes, since the fine fraction remains when the recycled coarse aggregates are used, which storage and control is complex. Dr. Khatib, an environmentalist, illustrates that concrete made of 25% and 100% of RFA reduce compressive strength by 15% and 30%. However, another research at hand demonstrate that the compressive strength is not affected by the utilization of RFA, but the most significant changes within concrete with RFA is the higher drying shrinkage and less durability. Previous studies have been made on the use of RFA in concrete which show that the use of RFA over 50% produce significant decreases on the slump of the mixes at the fresh state, similar to those produced in concretes made with natural crushed sand.

With every new process that arises, there are impacts to the economy, the environment and society. It is first interesting to understand the economic impact of RCA. The cost of aggregates typically is between 20 and 30% of the cost of materials and supplies, or 10 to 15% of the total construction cost of a roadway section. Due to the high quality of virgin aggregate and its known shortage, the price is increasing. Since there is a shortage in virgin aggregate and the price is increasing, access to this very important construction material is decreasing and an economical option is crucial. The good news is that concrete pavements are 100% recyclable. Concrete recycling has been used predominantly in Europe since the 1940s and in the U.S. since the 1970s. Concrete recycling for paving applications is now performed in at least 41 states and has the support of the Federal Highway Administration. The FHWA has found that reusing the material used to build the original highway system makes sound economic, environmental, and engineering sense. The cost of aggregate is one of the major costs of highway construction. As the sources of virgin aggregate becomes scarce, haul distances increase, which then cause additional supply costs. As the source becomes scarcer, the more the costs of using virgin aggregate will increase. The cost of producing RCA can be considered to be limited to the costs of crushing the demolished concrete and screening and backhauling the RCA. The cost of removal and demolition of concrete will stay the same, regardless of whether it is natural aggregate or recycled concrete (RC). However, the usage of RCA can produce savings in the hauling and disposal costs, especially if the RCA is produced on site. Moreover, the waste issue comes back when the economical benefits of RCA are discussed. Disposing of demolished concrete slabs in landfills is becoming expensive because the space available in landfills are also becoming limited. The recycling of concrete pavement annihilates the need to dispose the concrete, which results in cost savings and allows more room for our landfills to be filled with waste that cannot be recyclable.

Other than impacts stemming from cement production, transport has a large influence on the environmental load which is then dependent on transportation distances and the transportation vehicle used. Regardless of the transport scenario, the impacts of cement and aggregate production life-cycle phases for RAC are slightly larger than for NAC. In consequence, the results present the fact that the impacts of cement and aggregate production phases are slightly larger for RAC than for NAC. There are varying studies that show that sometimes NAC has higher impacts on the environment and other studies show that it is RAC that could be costing more impact economically, environmentally and ending up affecting the social aspect as well. Total environmental impacts in terms of energy use, global warming, eutrophication, acidification and photochemical oxidant creation depend on transport distances and types. By observing a study done by Dr. Marinkovic on the matter, I understand that transport scenario 1 (transport distances of recycled aggregate are smaller than those of natural river aggregate) the environmental impact of RAC and NAC production in terms of studied impact categories is approximately the same and the benefit from recycling in terms of waste and natural mineral resources depletion minimizing is clearly gained. Whereas scenario 2 indicates (transport distances of natural and recycled aggregates are equal), the total impacts of RAC are larger, increase ranging from 11.3% to 36.6% depending on the impact category.

This then trickles down to having the process of RCA also reduce the emission of greenhouse gasses (GHGs). Every activity that requires fuel and/or electrical
power when producing virgin aggregate is inevitably responsible for the creation of GHGs and other pollutants. Concrete recycling helps to reduce the environmental impact of pavement reconstruction activities while helping to ensure the maintenance of our transportation infrastructure. Another environmental benefit that RCA produces is that it lowers the carbon dioxide (CO2) levels in the air. Research at the University of New Hampshire has shown that RCA has significant value as a sink for carbon dioxide (CO2), a primary greenhouse gas, through the mechanism of spontaneous carbonation, in which atmospheric CO2 reacts with calcium hydroxide (Ca(OH)2), a by-product of the cement hydration, in the concrete mortar to produce calcium carbonate.

In order to continue the wave of recycling, many participants of the Global North have been increasingly adding to their lifestyle. The recycling of concrete aggregate also needs to begin and be woven as a process in Canada and needs to be regulated under its government. One interesting factor about recycled aggregate is its use for an abundant resource at the moment, which is water. However, this precious resource is endangered for beginning to be scarce. Although there is a lot of water on earth, less than 3% is fresh and most of that is either locked up in fast-melting glaciers and ice caps, or is too deep in the earth to retrieve. The status of water being an endangered natural resource is in part due to the rise of global warming and the growth of agricultural, urban, and industrial needs, where water is increasingly used to keep up with the demand of various industries. Therefore, our resources need to be used more efficiently so if we do not cut back on the water usage and concrete in construction, then this industry could be adding to the woes humans will have to face when there is a shortage of water. Concrete companies and constructions sites, being the largest industrial consumers of fresh water, it is crucial that the concrete industry use water more efficiently. Approximately 100 L/m3 (20 gal./yd3) wash-water used by the ready mixed concrete trucks, we're using too much water for concrete mixing and the yearly global mixing water requirement of 1 trillion L can be cut in half by better aggregate grading and by greatly expanding the use of mineral admixtures and superplasticizers. Drinking water has been identified as being acceptable for making concrete so there is no harm in not using fresh water all of the time for recycled aggregate.

As it stands today, there are no virgin aggregate resources available in Canada. If there are no virgin aggregates available for usage due to the shortage, then there will no longer be any concrete developed for construction. If there are no construction materials being produced, then as a result, there will be a shortage in jobs available not only in the construction industry, but in contracting, renovating and real estate. The effect of this crisis will also cause architects, civil engineers, construction workers, miners, and geologists to suffer cuts in their industries. This negative impact does not only effect society but most importantly, the economy. By replacing virgin aggregate with RCA and RFA, this will not only conserve our resources for future generations, but it would also aid the environment in beginning a cycle of recycling in a new sector where concrete is used. Tapping into a system that introduces a product that is a hundred percent recyclable like recycled concrete aggregate is a large movement forward in saving the environment because as shown, using virgin aggregate is not feasible due to its shortage but the methods used with this product is not helping the environment either. RCA can open up new spaces in landfills, it can conserve our water and disables toxins to disperse in our atmosphere. It is crucial that Canada jump on the bandwagon of recycling concrete aggregate as part of their goal for a "greener" society.

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Tuesday 24 October 2017