How to mix concrete Invest. Consult. Concrete is one of the most simple and best known building materials and probably the most vital for the strength of the constructions of your building, parking lot, patio, garden wall, paths etc. That is why it is important to know how to properly mix and pour concrete. Concrete contains only the following ingredients cement Portland, gravel, sand and water. When cement is mixed with water a chemical reaction takes place. The cement does not simply dry it reacts with the water binding the materials in a concrete mix firmly together and harden into an incredibly strong rock like mass. Gravel and sand are called also aggregate and all you need to know how to mix concrete properly is the correct aggregate to cement ratio. The more cement the stronger the concrete. The strength of a concrete mix is measured in grades. CRETEDEFENDER Dont cover up concrete problems Prevent them How to Pour a Concrete Patio. Patios can be wonderful additions to any home, but homeowners generally have to weigh the benefits of having a patio with the. Removing Stains from Concrete. Even after power washing, some stains may remain. Here are some tips that may help OIL Apply bleach to the stain using a spray. There are different concrete grades for example C1. C2. 0, C2. 5. The grade of the concrete means the concrete compression resistance after 2. It is done in Newtons per square millimetre. A concrete of Grade C1. Nmm. 2 per square millimetre in 2. Proportions for different grades For grade C1. Concrete_Control_Joint061-DFs.jpg' alt='How To Avoid Concrete Cracking After Pourn' title='How To Avoid Concrete Cracking After Pourn' />Pouring concrete requires precision and skill. Cement driveways are known for cracking, and in many cases, soon after theyre poured. Cement Sand Gravel. For grade C2. 5strong. Cement Sand Gravel. For grade C3. 0very strong. Cement Sand Gravel. Remember the proportion is done in terms of volume. This means the above proportions are correct if using the same measure. For example 1 bucket cement 2 buckets sand 5 buckets gravel. Simple Calculation for 1 cubic meter of Concrete. Concrete. Mixture of half cubic meter sand, one cubic meter of gravel and a portion mix of cement for the required strength of the concrete plus water, there will be about one cubic meter of volume. For example 0. 5m. Concrete C2. 5 grade. Volume measures for cement, gravel and sand Cement Portland 1. Gravel loose, dry 1. Sand dry 1. 60. Pressure calculators 1 Newton N 0. Kg force. 1 Pascal 0. Kgm. 2 1 Nm. 21 Megapascal 1. Kgm. 2 0. 1. 01. Nmm. Megapascal 1. The usual required strenght of the concrete are For C3. MegapascalNmm. 24. For C2. 5 2. 5 MP Nmm. For C2. 0 2. 0 MP Nmm. For C1. 5 1. 5 MP Nmm. Another factor which determines the strength and hardness of the finished concrete product is proper mixing of the ingredients. If the ingredients are not thoroughly mixed there will be differing degrees of hardness in various parts of the finished product. Needless to say this is something to avoid at all costs. How To Avoid Concrete Cracking After PouringCement can be mixed by hand by a reasonably fir person, by a cement mixer or it can be ordered to be delivered ready mixed. Mixing concrete by hand is exhausting and can be done only for small quantities max. For larger projects it is better to be be delivered ready to your site. While it is very easy to order concrete you have to know what to oder how much concrete how many cubic metres what grade time of the delivery. Once you have the concrete is delivered you have to be prepared to handle it. You should also consider access for the lorry, and you should be aware that the driver wont be willing to wait long. That is why you should be fully prepared for the concrete also considering that concrete is getting hard pretty fast and you will not have more than 1 2 hours to handle it Foundation concrete for 1 cu metreGeneral purpose concrete for 1 cu metre 6 x 5. How to mix concrete by hand. Select mixture formula from the table above. A 1 2 3 cement sand gravel is also a bullet proof formula. Use a shovel to mix to ingredients in a wheelbarrow or on a large plate of sheet iron on the ground. Add some water and continue mixing by hand. Use minimum volume of water possible. The less water the stronger the concrete. While keeping water minimal be sure that there are no dry areas in the mix. Work fast as concrete dries out fast. Tip. You can also buy pre mixed bags of ready to mix concrete at DIY supermarkets and lumber yards. These require water and mixing the measuring is already done for you. If you have doubts about your ability to work and finish concrete, hire professionals. Any job over a few square feet in size may be more than the average homeowner wants to tackle. Concrete Thickness. Recommended minimum thickness of the concrete for the following projects are Footpaths 7. Patio 1. 00mm 4 inchesDriveways and Parking areas 1. Base of light structures 7. Slope of the concrete. Water will gap in depressions without a slab and if there is no natural slab of the land it should be calculated. Any concrete against a building or a garden wall must slope away from it. Here the reccomended slopes Footpaths minimal, just to avoid areas where rain water will collect. Patio 1 6. 0 1. Driveways and Parking areas 1 4. Base of light structures 1 8. See full Metric system conversion tables opens new windowWhat does it mean to cure concrete Curing is one of the most important steps in concrete construction, because proper curing greatly increases concrete strength and durability. Concrete hardens as a result of hydration the chemical reaction between cement and water. The hydration occurs only if water is available and if the concretes temperature stays within a suitable range. During the curing period from five to seven days after placement for conventional concrete the concrete surface needs to be kept moist to permit the hydration process. Temperature extremes make it difficult to properly cure concrete. On hot days, too much water is lost by evaporation from newly placed concrete. If the temperature drops too close to freezing, hydration slows to nearly a standstill. Hot weather concreting. There are certain problems which may occur when mixing concrete in hot weather. The high air temperature and the low humidity which are typical for the summer months are factors that may affect the process of concrete curing and may spoil the quality of the concrete structure. Most of the problems associated with pouring concrete in hot weather conditions relate to the increased rate of cement hydration at higher temperatures and the increased rate of evaporation of moisture from the fresh concrete. The properties of concrete that may be affected by hot weather conditions include Setting time Due to the high ambient temperatures increases also the concrete temperature which reduces the time for mixing, pouring, compacting and finishing of the concrete. Workability and slump Higher temperatures reduce the slump of the concrete more rapidly with time and more mixing water is needed to improve the workability of the material. Adding more water decreases the strength and increases the permeability of the concrete, thus affecting its durability. Compressive strength Higher water demand and higher concrete temperature could lead to reduced 2. If more water is added to the concrete mix at higher temperatures to maintain or restore workability, the water cement ratio in the concrete will be increased, resulting in a loss of both potential strength and durability. This may also increase the drying shrinkage of the hardened concrete. Where water is not added, the reduced setting time and workability increase the potential for inadequate compaction itself of a major influence on strength, the formation of cold joints and poor finishes. The watercement ratio however should be as low as possible to improve durability of the surface. Too much water in the mix will produce a weaker, less durable concrete that will contribute to early flaking and spalling of the surface. Poor surface appearance With the increased rate of evaporation, the surface of the concrete will dry out and stiffen. In the case of flatwork, this may lead to premature finishing of the surface, trapping an amount of bleed water within the mix. The compacted surface layer from finishing may cause the rising bleed water to be trapped below the surface, resulting in debonding of the surface layer and subsequent flaking. How to Pour a Concrete Sidewalk. Step 1 Planning and tools. Front walk site Stick to sidewalk projects in flat or gently sloping areas. Adding steps is much more complicated. If the thought of pouring concrete scares the bejeebers out of you, dont feel like the Lone Ranger. This story will teach you the basics so youll be confident and ready to go when the concrete truck pulls up to the curb. And youll save to cost of hiring concrete pros to boot. You may need a building permitcheck to be sure. At this site, we didnt need a building permit for a residential sidewalk on private property. But take five minutes and call your local building inspector to make sure thats true in your area. Youll save some embarrassment and possibly a fine. A giant ready mix truck driving up to your house can be intimidating. I always get butterflies when I hear the diesel roaring a half mile away. But being prepared with solid forms, good equipment, a couple of strong helpers and a well planned wheelbarrow route will help calm the nerves. Once you dump the first few wheelbarrow loads and get the hang of moving the wet mud around, youll feel in complete control. Youre going to need a couple of heavy duty wheelbarrows, shovels, rakes and a variety of professional grade concrete finishing tools. We describe the tools in detail below. The hand tools may be worth buying if you intend to pour more concrete down the road. For a modest price you can own a set of high quality tools minus the wheelbarrows for life and not have to hassle with rentals. Take heed. Concrete is heavy and time is short. Once the ready mix truck the concrete is premixed and ready to pour shows up, you and your helpers will be muscling around 2. This work is intenseyou wont be taking any coffee breaks for a while. After pouring and screeding Photo 1. Follow the tips and advice in this article, get ahold of the right professional grade tools, line up at least two reliable, beefy helpers and pick a good weather day, and youll end up with a long lasting, attractive sidewalk youll be proud to carve your initials into. Concrete might be the cheapest building material on the planet. Its hard to imagine a material that gives more bang for the buck than concrete. What other material yields a permanent, finished, durable, maintenance free outside surface at a low cost and a days workAround these parts, many contractors wont put down a gravel base or even use steel reinforcing. Bonus Your sidewalk will be stronger and last longer than many professionally poured sidewalks. In addition to the cost of concrete, suppliers usually add a short load charge for small orders generally under 3 yds. This 4 ft. wide by 6. Two Heavy Duty Wheelbarrows Can Save the Day Secure your tools a day ahead of time or at least contact the rental store to reserve them for the pour day to make sure theyre at the site when the truck comes. Rent each of these tools Contractor grade wheelbarrows with leak free tires. Even on small pours, youll be in big trouble if your sole wheelbarrow gets a flat tire or a broken handle, so get twoItll also speed up the pour. A full ready mix truck at the curb with no way to unload it is expensive. Concrete is heavy. The neighbors garden grade petunia hauler will collapse under a load of concrete, and the hard, narrow tires make for tough wheeling in soft ground or gravel. Bull float with an extension handle Photo 1. Concrete broom Photo 1. A groover that cuts control joints 1 in. If the rental store only has groovers for shallow cuts, use it to shape the joints and deepen them with the corner of a trowel or a stiff putty knife. Unless the grooves are at least one fourth the thickness of the concrete, theyre of little value. Two magnesium hand floats. Two edgers. Iron rake to move around wet concrete Photo 1. In addition to the earth moving equipment for the excavation work, youll need Hand maul for pounding in stakes. Bolt cutters Photo 8 for cutting mesh. Sod cutter Photo 2 if you have lots of grass to cut through. Screw gun for anchoring forms to stakes. Circular saw for cutting forms. Marking paint for outlining the walkway. TIP Fill a wheelbarrow with water, and brush and rinse off your tools every time you use them. Magnesium floats. Concrete edger and groover. Step 2 Excavate the walk Photo 1 Lay out the walk Rip 1. Use marking paint upsidedown spray paint to mark the ground next to the form. To outline the sidewalk for digging, mark the unformed side using a spacer block. Photo 2 Dig out the sidewalk path Slice off sod with a sod cutter rents for 1. Dig out about 3 in. Set aside some topsoil to fill against the forms see Photo 7 and sidewalk later. Digging out the path is 8. Lay out the path with 6 in. Photo 1. Thatll not only give you the overall shape but also provide the forms to mark the outline for digging. Youll also find out if curves are too sharp for the bending qualities of the siding. It took two of us a whole day to cut off the sod Photo 2 and dig out the path to prepare the base for this sidewalk. Free Download Setup For Visual Studio 2005 Professional Compatibility. Believe it or not, pouring and finishing the sidewalk was easier, faster and a lot more fun than excavating. Tree roots, stones and heavy clay made for tough digging. Renting a sod cutter to remove sod, and using axes for cutting out roots and pickaxes to loosen soil make the job a little less blister producing. Start thinking about drainage issues at this point. If water tends to collect in the yard in spots, you may want to elevate the walk in those areas, so dont dig as deeply there. Long, flat areas should have one side of the sidewalk lower so water can drain off the side. In most cases, make the top of the finished walk even with the freshly cut top of the grass for easy mowing and a neat, clean appearance. The bottom of the trench will be about 6 in. If your sidewalk abuts another sidewalk or driveway, keep the top of the sidewalk at the same level or build in a 4 to 7 in. Dont make a step thats shorter than 4 in. Youll trip every dinner guest who comes over. Tip If you dont have a place to dump excess soil and sod, rent a trash container for a couple of days. We ordered a 1. 0 yard unit for 2. Step 3 Build the forms Photo 3 Drive stakes every 3 feet Pound in two stakes about 1 ft. Screw the forms to the inside of the stakes with a couple of 1 14 in. Bend the forms to make smooth curves, anchoring them with more stakes every 3 ft. Keep the tops of the forms about 1 in. Photo 4 Reinforce form joints Cut 1. The splice will smooth out the curves at butt joints. Photo 5 Space and form the second side Space and level in the opposite form sides using a homemade gauge board just a 14 thats a few inches longer than the width of the sidewalk. Screw short blocks onto the bottom spaced the same width as the sidewalk. Use this gauge board to position the forms and stakes to keep a consistent width the entire length of the sidewalk. Rest a 4 ft. level on top of the gauge board to keep forms level from side to side. For better drainage in long, level areas, drop this side about 1 in. Photo 6 Pack the soil Pack the underlying soil with a plate compactor rental. Its important to uniformly pack the entire base including the sides near the forms. Photo 7 Spread gravel Spread gravel 4 in. Pack dirt against the outside and gravel against the inside of forms to add support when pouring and to achieve smooth curves. Its not necessary to compact the gravel. Photo 8 Cut concrete mesh to fit Cut off the stakes flush with the tops of the forms. Park a helper on the end of the reinforcing mesh for ballast and unroll the mesh, holding it down with your feet. Cut it to length with a pair of bolt cutters. Flip the mesh over and pull one end toward the other to back bend it slightly to eliminate the natural curl. Cut the edges of the mesh at least 3 in. Photo 9 Wrap mesh ends Overlap mesh layers at least 6 in. Use cheap hardboard siding to form even the tightest curves.