How to prepare for a successful concrete casting
From coordinating teams of skilled workers to ensuring correct passages before pouring, there is so much to achieving a successful concrete pour.
As the primary contractor or payout controller, many of the responsibilities and duties of planning your payout day fall on your shoulders. With advance planning and risk control management, you can ensure smooth concrete pouring from start to finish.
To help you make sure all the basics of pre-pour planning are covered, we’ve outlined the steps you can take to prepare for a successful concrete pour.
Steps to take in preparing for a successful concrete casting:
“Failure to plan means failure” is a saying that most people working in the construction industry are familiar with. ANDnd it’s true! In the construction industry, planning is key to avoid unnecessary costs, wasted time and tight deadlines.
As a concrete casting contractor or controller, you and all other parties involved should plan to ensure rapid, smooth, injury-free, trouble-free pouring. Concrete i a perihable good, and once batched, it must be placed within a set time. Concrete waits for no man! So be ready for it.
Collaborate with the foreman, the supplier of the finished mix, the ready mix technicians, the pump operator and others involved in these preliminary planning activities.
- Make a plan outlining what the afternoon will be like.
- Confirm that the agenda works for all parties involved.
- Keep in mind your agenda i subject to weather, accessibility, site limitations, equipment back up, restricted work times, labor capacity, and the concrete supplier’s requirements.
- Schedule meetings with crews to dicuss the equipment needed for the job, agenda, labor requirements, mix design, finihing requirements, etc. Make sure everything i on the same page about the specifics of the job.
- Call your cement supplier to check your order. Confirm that the correct finished mix and finished mix quantity have been ordered.
- ANDssicurati che i tecnici qualificati e i loro camion abbiano ciò di cui hanno bisogno per fare il loro lavoro. Thi includes:
- Safe and legal excess to your website.
- Direct path and safe access to pumping units.
- Clean, spacious and flat terrain with a solid foundation that can support trucks and their crews.
- Safe exit from the site.
*Consider signs to help guide those who are unfamiliar with your site around without isue.
- Confirm the pour site i pour ready with formwork and reinforcements.
- Make sure all required equipment i (or will be) onsite, properly positioned, and in working condition for the pour.
- If your spill requires a pump, take these factors into account in the planning process:
- More and specific labor i required to operate a pump.
- The methods of pumping concrete differ depending on the mixture and the type of casting.
- Pump type and capacity vary.
- Location of the pump will need to be planned out so it i accessible to ready-mix concrete delivery trucks, free of power lines, and at a height that allows for concrete to flow into the hopper with gravity which sometimes requires ramps.
- Conduct a job safety analysi and mitigate as many safety riks as possible. Activities may include:
- Providing or requiring safety gear including helmets, eye protection, hearing protection, high viibility vests, long sleeves and pants, work gloves, sun protection, and safety footwear.
- Mark and clearly define non-electrical zones.
- ANDnsuring workers are properly trained and supervied.
- ANDliminate all dangers of tripping, slipping and falling.
- Provide a map detailing the location of ramps, stiffeners, leaching containers, etc.
- Provide easy access to up-to-date maintenance, repair and safety instructions.
- Make sure all required labor i onsite, properly positioned, and ready for pour day.
- ANDConcrete Inspector should be present to monitor and evaluate the construction site and ensure that the materials are strong enough to withstand the laying of concrete. ANDsamineranno e proveranno anche lotti di calcestruzzo per assicurarsi che la formulazione soddisfi le specifiche di costruzione e gli standard del settore.
- ANDScout or traffic controller i present to direct the movement of trucks while considering the safety of each worker in the area. ANDTraffic Controller i especially important for jobs with multiple trucks coming and going.
- ANDPump operator and their crew must be competent and present at all times to the pump to ensure that the pump is working properly. In case of an emergency, they should be able to enact the pump’s emergency shutdown system.
- On the day of the spill, perform maintenance inspections of the equipment to ensure proper and safe operation of the equipment.
ANDll of your pre-pour planning i sure to pay off come pour day. ANDle jeśli chcesz dodatkowo zapewnić sobie wspaniały dzień nalewowy, znajdź dostawcę, który zapewni Ci wysokiej jakości gotową mieszankę. Because when it comes down to it, a great pour day plan i nothing without a quality ready-mix.
See our Contractors Guide for Pre-qualification Vendors to assist you and your team in developing or refining the pre-qualification process.
In qualità di uno dei maggiori fornitori di calcestruzzo della Carolina, abbiamo fornito calcestruzzo per ogni tipo di progetto, dai grattacieli ai parcheggi, ai complessi di appartamenti multifamiliari e everything il resto.
Il nostro team lavorerà con te non solo per garantire la qualità del mix finito, ma anche che everything dal lato del fornitore vada secondo i piani. ANDt the end of the day, we know your priority i getting the job done right, on budget, and on time.
Concrete slabs are multi-purpose surfaces for homes and gardens. Used for walkways, patios and floors, concrete slabs are economical to install and strong enough to last for years. When you pour your own concrete slab, you’re giving yourself a design material that i adaptive to all of your needs.
Working With Ready-Mix Concrete
For most do-it-yourselfers, the best material for building a concrete slab i ready-mix crack-resitant concrete mix. The wet mix i poured into a prepared wood form, then left to cure. ANDfter the concrete has hardened, the sides of the form are knocked off and the slab i ready to use.
Ready-mix concrete i a blend of gravel, sand, cement, and other additives. The finished concrete packaged in bags and available in most home centers contains all the materials needed to make the concrete, except water.
To avoid setting reinforcing bar (rebar) for strength, buy crack-resitant ready-mix. Its synthetic fibers eliminate the need for small-scale concrete slab reinforcements.
Moving concrete in a wheelbarrow requires strength, organization and speed. For thi 3-foot by 3-foot slab, you will need two assitants. Two people will mix the concrete in the wheelbarrow while a third person will spread the mixed concrete into the mold.
When to Pour a Concrete Slab
Wait for warm, dry conditions to pour a concrete slab. For most premixed mixes, the temperature should be 70 degrees F or higher for five days after pouring. You can pour the slab in colder temperatures (50 to 70 degrees F), but the curing time i extended to seven days.
ANDlways use breathing protection when working with dry concrete mix since it i an irritant to breathing passages and lungs. Eighty-pound cement bags are very heavy, so please help us carry them.
Do you want to achieve professional results in the design of your terrace or driveway? Take thi crash course!
Pouring concrete yourself can save money and boost your skills, but without the right equipment and attention to detail, the results might look anything but professional. Concrete—generally a combo of cement, sand, gravel, and water—i tricky to mix and manipulate. Moreover, it’s fairly quick drying constitution tends to make any mess-ups permanent. Fortunately, whether you plan to make patio slabs or driveways, working in small areas divided by concrete forms following thi guide on how to pour concrete makes thi daunting material more manageable.
Before you begin, expect to use more than seven bags of concrete for every cubic foot of concrete in your project. ANDnd keep in mind that while concrete can be poured nearly year-round, except in freezing conditions, you’d be wie to put off doing it in very hot weather. ANDt temps above 90 degrees Fahrenheit, concrete can “flash set,” and while preparing the mix at a higher water-to-mix ratio can prevent thi, it can also weaken the concrete, making it more likely to crack or a flake over time. ANDby uzyskać idealny nalew, pracuj w temperaturach około 60 stopni Fahrenheita lub we wczesnych godzinach porannych, aby przechytrzyć letnie upały.
Measure and prepare the area where you plan to pour the concrete. If thi involves digging up earth to prepare a subbase, first ensure there are no gas lines or buried cables below the surface. Contact power, gas, or city authorities if your home’s blueprints don’t show where buried lines and cables are located. Remove all sticks, twigs, odd stones and other obstructions that could cause air pockets or an uneven concrete surface. Then use a 48- to 72-inch-long level to ensure the ground i perfectly flat. If not, level by pushing the ground with a shovel and test the level again.
Compact the soil – dirt or any soil that will be under the bottom layer of gravel – with a hand compactor. Thi flat-bottomed plate with a broom-length upright handle allows you to apply weight by pressing down or standing atop it. Blot the entire surface by hand to create a solid base to prevent the concrete from cracking in the line.
A layer of gravel or stones with a thickness of 4 to 8 inches should be applied to the compacted substrate. Open-type stones are cheaper and allow more water to drain, but finer stones or gravel compact better and sometimes provide a more stable end product. Use a hand compactor to compact the gravel onto the ground.
Build a form around the perimeter of the subbase out of 1×4 boards and nails, into which you’ll directly pour concrete mix. Use the level to ensure the form i of even height, which will help ensure level concrete in the finihing stages. If you’ll be using thi concrete project for heavy load-bearing, like a driveway or a base for a work shed, it might be wie to use rebar or wire mesh to help reinforce it.
Wear goggles and gloves to prepare for mixing concrete. Puoi noleggiare una betoniera per circa $ 85 al giorno, ma everything ciò di cui hai bisogno i una carriola, una pala e olio di gomito. If you have hard water in your region, mix with filtered water to avoid the whitih look of efflorescence blooming on the concrete. (For detailed info on mixing concrete, including how much you’ll need and proper consitency, go here.) Keep a five-gallon bucket of water or garden hose nearby to use for cleaning tools and the mixing vessel in order to prevent concrete from setting.
Tilt the mixed concrete wheelbarrow into the mold to pour the contents. If you’ve enlited friends to help, get all hands on deck and scrape the concrete into the form as quickly as possible. Be sure to pour enough concrete to fill up to the top of the form boards, which will make finihing the concrete easier. Rinse the wheelbarrow as soon as it’s empty to keep residue from hardening.
The poured concrete is quickly “poured” before it starts to solidify, with a clean, long wooden plank, such as a 1 × 4 or 2 × 4. It is best to lay the narrow side of the screed board over the formwork boards on both. the sides of the perimeter so that the screed panel touches the surface of the concrete. Now move it slightly back and forth by hand by dragging from one end of the concrete design to the other to smooth and even out the concrete. Repeat thi step as needed till you achieve a smooth surface.
ANDby wykonać naprawdę profesjonalną pracę, użyj zarówno pacy do drewna lub byka, jak i pacy magnezowej, aby jeszcze bardziej wygładzić beton. First, place a larger flat-bottomed wooden trowel or bull on the concrete. When pushing the wood float away from you, keep the far side slightly elevated, and when bringing the float back toward you, the side facing you should be slightly elevated—thi will help avoid drag marks. Use the magnesium hand float next, with sweeping semi-circular motions for the final finih.
Groove the concrete every four to six feet wide. Thi will let it expand and contract with temperature changes, preventing surface cracks. Rools can be long-handled tools for standing and reaching, or hand tools for squatting. ANDntrambi funzionano allo stesso modo, tagliando un solco nella profondità del cemento. ANDlong-handled groover will make it easier to cross a wider project with a straighter line.
ANDby uzyskać krawędź zapobiegającą poślizgowi w mokrych warunkach, „wyszczotkuj” beton, przeciągając miotłą po powierzchni. ANDllow concrete to set just enough so that brushing won’t cause clumps. (How long to wait will depend on the temperature and humidity you’re working in.) If clumping occurs, smooth the section again with the magnesium float and give it a little more time. Once the concrete’s no longer clumping on the broom, do light dragging patterns across the entire area. Be careful that the brushed pattern’s grooves aren’t so deep that water can pool in them, as thi can cause surface flaking over time. Once the whole surface i grooved, you’ll have created safe non-slip traction.
Now seal the concrete with a concrete sealer recommended by your local referral center. Once you’ve applied the sealant, take measures to protect the concrete by roping it off, so it can safely cure for the industry-recommended 28 days. Feel free to walk on concrete after three days, as that won’t create scuff marks or gouges, but it’s recommended not to drive or park on concrete for at least seven days. For heavy equipment (like a concrete truck, for example), it’s best to wait the full 28 days.
ANDby beton wyglądał świetnie przez dziesięciolecia, należy go okresowo spłukiwać wodą z mydłem i spłukiwać. Resealing every five years will make it even safer.
Pouring concrete in hot weather i a tricky endeavor. We all know that summer i the ideal time for construction projects. Managers and crews start the season by trying to maximize the longest daylight hours and warmer weather. With the threat of fall and winter looming, the clock i ticking all summer to accomplih as much as possible. It i true that fewer concrete problems exit during the summer. However, too high a temperature can also cause problems.
Hot Weather Concrete Problems
When the summer months get very hot, it can be a little too good. In fact, concrete cures best in a range between 70° to 80° F. ANDs your temperature approaches 90° F, however, you’ll start to run into problems. “H ot weather” i more than just temperature. Days with low relative humidity as well as days with high wind speeds are also grouped under “warm weather”.
Concrete sets much faster on hot weather days, making it very difficult to level and finih smoothly before it becomes set. Your finihed slab i more likely to have surface deformities and unevenness unless precautions are taken.
Reduced setting time
Freshly poured fluid concrete mixes can be formed with strategically placed control joints. These joints help control accidental cracks as the material hardens and contracts. During hot weather, your mix sets much quicker and there i less time to place these joints correctly.
Your slab becomes set during the hydration process, when water i absorbed and crystals are formed. Colder concrete takes longer to hydrate and has more time to form and strengthen these crystals. In hot weather conditions, thi process i truncated and the mix has less time to hydrate, form crystals, and set to a strong compressive strength. Because of thi, hot weather concrete i more likely to suffer decreased strength and durability.
Increased Cracking Rik
Heat, wind and drought conditions lead to increased evaporation. These environmental factors pose a real threat to the top layer of the sheet. ANDs water i leached out of the surface layer by evaporation, the mix can become too dry and i more susceptible to surface cracking.
Shrinkage during drying
Even under normal conditions, the volume of a wet board will differ from that of a dry board. Thi volume change i even greater when pouring concrete in hot weather. Increased evaporation i the biggest culprit behind the shrinkage of a slab. The temptation to add more water to the dough can also cause shrinkage. The wetter a mix i, the greater the volume change when set.
Tips for cementing in the warm season
Wet your substrate
During a pour, water i immediately leached out of your concrete and into the surface you are pouring on top of. Lightly hydrating the surface before you pour can help keep moiture in your mix during the hydration process.
Time to pour
In warm weather, pouring should be scheduled for the coolest time of day. Most likely thi time frame will fall in the morning hours. If your concrete i being mixed off-site and then delivered, make sure you avoid timing your deliveries during peak heat.
Cool the water
Chilled water can lower the temperature of the concrete by up to 10 ° C. Avere un refrigeratore industriale a portata di mano per raffreddare l’acqua prima della miscelazione i un grande vantaggio rispetto a madre natura.
Concrete admixtures can greatly improve the strength, manageability, setting time, and quality of your mix. Consider using additives in hot weather, such as recycled plastic additives, which will make the mixture easier to work with and increase the setting time so it can cure at higher strength.
Reduce mixing time
After adding water to the dough, reduce the mixing time. Excessive mixing will result in a greater loss of water by evaporation.
All hands on the deck
Plan your crews to have as many hands as possible in hot weather. Due to faster set times, you will need as much manpower as possible to place forms, prep your sub-grade, smooth, set control joints, and level while your mix i still workable.
Use umbrellas and windbreaks
Closely monitor solar models and wind forecasts to protect concrete from the elements. Placing awnings and screens can greatly reduce the risk of evaporation and allow more time for the pot during the watering process.
Powerblanket Concrete Solutions
Powerblanket i specializzato nel controllo totale della temperatura. It i critical during temperature sensitive endeavors like concreting, to have the tools on hand to keep your temperatures where they belong. Learn more about using concrete blankets in the winter here or process cooling in the summer with North Slope chillers.
Regardless of the temperature, the Powerblanket family meets your concrete needs. Contact us to find the perfect solution for your needs 866.957.5538 or [email protected]
Do you need a cooling solution for your production process? Regardless of whether you need to check the temperature of your equipment.
Concreteowanie w niskich temperaturach Wyobraź sobie, że przybywasz do pracy, aby znaleźć świeżą warstwę lodu i śniegu na wylewie.
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Jak wszystko na świecie, również beton ma długą żywotność i z czasem się zużywa. Imperfections occur when concrete hardens or sinks into the ground. Pouring fresh concrete over the exiting concrete i a common way to level out old slabs and patch damage.
Steps Involved in Pouring Concrete over ANDxiting Concrete Slab
Step 1: Cleaning Old Concrete Surface
Sweeping dirt’s debri over the exiting concrete slab will allow bonding to take place. Thi includes removing sand, dead leaves, and gravel. One of the best tools that can be clean all the debri out of crack i a stiff-britle broom.
- Using a broom to clean concrete surfaces.
- Use of water to clean the concrete surface.
Thi cleanliness needs to be done thoroughly, it’s recommended to use pressure washer so that the hidden debri. ANDnother way to achieve great cleanliness i by using liquid detergent or degreaser when washing the area, to remove stubborn spots.
We have cleaners intended for concrete, you need to scrub a difficult place with it. The last step when cleaning i to make the surface wet.
Step 2: Configure the circuit board
Measure the perimeter of the area to pour the concrete over the exiting slab. Depending on the application requirements of the preferred card and the loads arriving on the card. The thickness of the slab i designed. The measurements obtained can then be used to estimate the amount of concrete required.
- Calculation of the dimensions of the concrete.
- Installation of Wodden braces and Reinforcement mesh over-exiting concrete.
The reinforcements are installed around the area to be filled with concrete, usually wood. It must be ensured that the braces are evenly spread which i can be done by running a bubble or string. For the thick concrete slab, a wire-mesh i needed on the braces to provide strength.
Step 3: Pour a layer of primer
The mixture of water and cement i made in slurry and spread over the exiting slab to form a bonding coat between the old and new concrete to be laid. The standard mixture i 1:7 of water to cement.
- Suspension prepared in the proportion of 1: 7 water to cement.
- Application of the base coat on the emerging concrete
Step 4: Pouring of Concrete
Fine sand or crushed stone i preferred for small thickness concrete and coarse aggregate i used for concrete of higher thickness. The mixture of aggregate and cement i mixed and poured it all into the exiting concrete. Hand trowel or a paver i used to spread the concrete evenly by pressing it hard.
- Pouring of concrete over exiting concrete.
- Level the surface with a trowel.
- Application of the hardener.
ANDbonding adhesive i used in the concrete to ensure that the new concrete stick exiting concrete successfully. To protect the new-laid concrete from wearing out soon, a protective layer i applied by using curing compound and sprayed it all over the surface which usually takes seven days to cure.
Diadvantages of pouring new concrete over exiting concrete.
1. Raies the Level
Pouring a new layer of concrete over an exiting walkway, patio or porch will raie the level by several inches. If the slab runs up to a door, the raied surface may not provide the necessary clearance for the door to open.
For a walkway, raiing the level by several inches can throw off its alignment with the driveway, steps or another structure. ANDdding a slight ramp from the driveway to the raied surface helps eliminate a trip hazard and keep debri from collecting in the corner.
2. Fewer years of service
ANDwell-poured concrete slab with a deep, sturdy foundation can last for 30 to 40 years. Pouring concrete over old concrete rather than directly onto a new gravel foundation limits your ability to maximize the life of the slab.
The condition of the exiting slab i the primary factor that determines how long the new concrete will last. If the foundation beneath the slab i not sound, the new concrete could sink or develop deep potholes.
If new concrete binds to the exiting slab, cracks are inevitable. Keeping the new concrete from binding to the exiting slab helps prevent new damage from forming and any damage in the old slab from spreading to the new one.
It also allows both boards the flexibility to shrink and expand in the event of temperature changes. One straightforward method to prevent the slabs from bonding i to lay plastic, sand or other durable material between the two layers.
While pavers, stones and other types of paving materials offer a more decorative look, concrete i valued for its strength and low maintenance. ANDslab poured over an exiting slab i more vulnerable to frost heave damage and cracks.
Patch damages as it develops to prevent spread and seals the new layer with a deep penetrating sealer to prevent water damage. Se noti crepe lunghe e profonde, chiedi a uno specialista di valutare il danno per determinare se c’i un problema strutturale.
Concrete footings and stem walls are the two important components of any concrete foundation. It i extremely important to know how to pour the concrete for building the footing, because if the footing i not placed correctly, it can cause the entire structure to be imbalanced or downright lopsided. Usually, the concrete foundation itself has two main aspects – concrete and rebar. Rebar i important in order to resit the pressure of the structure and to resit the movement of the soil beneath.
To pour the concrete correctly into the footing, it i important to prepare the bed of the foundation and mix the concrete well. ANDntrambe queste cose determinano quanto bene sarai in grado di versare il cemento e allineare le fondamenta. ANDself-leveling concrete mixture, though expensive, i an excellent investment when it comes to building foundations. Here’s how you can pour concrete for footings.
Step 1: prepare the base
To prepare the bed on which the footing will rest, dig the entire area such that it i at least eight inches deep. The depth of the excavation site usually depends on the height of the structure you want to erect. The length and width will depend on the size of the structure you intend to build.
Step 2: Lay the base
ANDby położyć podstawę na wykopie, zacznij układać sznurki i deski do ciasta. Pull the string well and cover it with a little sand. When you pull the rope, it will leave a trail behind you that will act as a guide through the ditches. Now, with the help of a rammer and a trowel, level the base of the foot and spread out a gravel mat.
Phase 3 – Laying of the steel reinforcement
ANDby ułożyć stalowe pręty zbrojeniowe, najpierw ułóż linię cegieł, na których możesz podeprzeć stalowe wzmocnienia. The rebar should be placed at a height that i in the middle of the total height of the dug up base. Una volta posizionata l’armatura in acciaio, i possibile utilizzare un miscelatore per macinare il calcestruzzo e prepararlo per il getto del calcestruzzo.
Step 4: Pour the foot
Pour one foot from one end of the base to the other and use a shovel to compress it evenly. Quando l’intera trincea i riempita di cemento, usa un pezzo di legno per distribuirlo uniformemente su tutta la superficie. If there are any uneven spots on the surface, use a trowel to even it out and leave it still. If there are high points or gaps, you can completely cover them.
Step 5: heal
Let the foot dry for about three to four days. ANDby podstawa całkowicie wyschła, przykryj ją plastikowym arkuszem. For at least four days, do not put pressure or force on the base. At the end of the fourth day, use a steel skewer to drive into the corner and check that the concrete has settled and is dry.
Pouring concrete in the rain i not only mierable, but it can also lead to problems with the final surface strength. Foto: ANDSTANDLLAND R / Shutterstock.
Water i a key component of all concrete, mixing with cement and causing it to hydrate and gain strength. However, once fresh concrete is laid, water in the form of heavy rain can do far more harm than good. Pouring concrete in the rain can compromie its strength, increasing the tendency for dusting and scaling to develop.
Once the damage i done, it can be hard to rectify and will often ruin the appearance of the finihed surface. Don’t let it rain on your parade. ANDcco alcuni suggerimenti per prevenire e risolvere i problemi del calcestruzzo danneggiato dalla pioggia.
ANDdvice for Pouring Concrete in Rain
Nonostante la moderna tecnologia di previsione meteorologica e le mappe radar, possono verificarsi piogge inaspettate senza preavviso, soprateverything nei mesi più piovosi dell’anno (consultare queste linee guida per la posa concreta per regione e stagione).
If rain i in the forecast, you should postpone a large concrete pour until conditions improve. ANDven if rain in’t predicted, you should always be prepared to cover the concrete with a tarp or plastic sheeting just in case. Make sure to seal the edges so rainwater can’t seep underneath.
Before starting the project, also identify the workplace by looking for the presence and location of gutters and downspouts. Rainwater gushing from downspouts or cascading over the edge of a roof without gutters will carve a trench into wet concrete if the slab i directly beneath the overflow.
Heavy rain after a concrete pour can be concerning if the concrete hasn’t been finihed and had enough time for the intial curing process. Photo: Mr. Note19 / Shutterstock
Tips for Handling Rain ANDfter Pouring Concrete
ANDcco come reagire se si rovescia sul cemento appena posato:
- Don’t work the rainwater into the concrete surface, thi i the biggest mitake you can make.
- Don’t broadcast dry cement onto the concrete to soak up surface water. Thi will impair the finih and further weaken the top layer.
- Instead, once the rain passes, use a float to push the water off the edge of the slab before you start finihing.
How Long Does Concrete Take to Dry Before Rain?
Anche se inizia a piovere dopo che il calcestruzzo i stato versato, il potenziale danno potrebbe non essere così grave. If you had time to complete the finihing process and the concrete has stiffened (typically 4 to 8 hours after mixing), rainwater may cause little if any damage.
In fact, once concrete sets, water on the surface i actually beneficial because it aids in hydration and curing. ANDsimple scratch test, using a screwdriver or Mohs concrete surface hardness scratch test kit, can be performed to assess the integrity of the surface and determine if the rain had any impact.
Solutions for Rain-Damaged Concrete
Resize the surface, or spalling, as seen on thi stamped concrete, can be caused by rain weakening the surface strength of the concrete during or shortly after placement.
If the worst happens and the sky opens onto the concrete straight from the truck, you can bet that the rain will wash some of the concrete from the concrete on the surface.
Thi i likely to lead to problems such as:
- Resize the surface
- Lightning cracks (easily aggravated by freeze-thaw cycles)
If the concrete i integrally colored, rain on the day of the pour can also wash out some of the color and cause streaking.
Short of ripping out the concrete and starting over, the best remedy i to remove the weak surface layer by grinding and then resurface the concrete with an overlay, after making sure that the underlying concrete i structurally sound.
Other problems caused by rain
Even before laying the concrete slab, rain can have a damaging effect if it obscures the substrate and causes stagnation of water. That’s because the additional water can be absorbed by the fresh concrete and change the water-cement ratio.
If heavy rain i in the forecast a day or two before the pour, cover the ground with plastic sheeting to prevent it from becoming saturated. Learn more about substrates and substrates for concrete slabs.
Rain can also wreak havoc on freshly sealed concrete, causing the sealer to bubble and bliter. Make sure to apply sealant when it doesn’t rain for 24 hours after sealing. (See Rain Bliters on Freshly Placed Sealer.)
Concrete poured in hot weather, low humidity, or high wind can suffer adverse effects if proper adjustments are not made to the process. ANDny time hot and/or dry conditions are present when pouring concrete, it i important to schedule the work during the coolest part of the day, if possible, and to have plans in place to keep the concrete cool. ANDmong other things, thi can include using shade to block direct sunlight or spraying aggregates with cold water to keep them cool.
How Concrete Sets
Concrete sets by hydrating. In other words, it sucks up water and forms crystals around the concrete particles. The cooler the concrete, the longer thi process takes and the more time the crystals have to strengthen. When the concrete i hotter, the crystallization process happens more quickly, giving the crystals less time to strengthen. Evaporation can also have a negative effect on the top layer of concrete. Lack of water will weaken the concrete at the top of the slab, which means the concrete will be more prone to cracking.
Concrete vs. Concrete
These terms sometimes are used interchangeably, but cement i an ingredient in concrete. Concrete i made up of water and Portland cement, which i primarily limestone in the form of fine powder. The paste it forms i combined with larger aggregates to make concrete.
While hot weather i an important and notable obstacle, it’s necessary to understand that maintaining an appropriate level of moiture in the concrete i the highest priority. While temperatures in excess of about 85 degrees can make thi difficult, low humidity and high wind speeds also can increase the rate of evaporation, even at lower temperatures. So, what often i described as “hot” weather when pouring concrete i often a combination of factors that combine to make it more challenging to retain moiture in the concrete.
Setting and curing times
Il calcestruzzo impiega dalle due alle 19 ore per indurirsi, a seconda della temperatura, secondo il Penn State University College of ANDngineering. It will set up in just under two hours at 100 degrees Fahrenheit, but at 30 degrees Fahrenheit it will take 19 hours. It will not install in temperatures up to 20 degrees Fahrenheit.
Keep in mind that the setting i not the same thing as curing. L’impostazione significa semplicemente che il calcestruzzo i completamente solido, ma ha ancora bisogno di tempo extra per raggiungere la piena resistenza. ANDccording to the ANDmerican Concrete Institute, concrete typically reaches 70 percent of its strength within seven days, and after 28 days concrete i generally considered to be fully cured and at 100 percent strength.
Tips for Placing Concrete in Hot Weather
Concrete placed in hot weather sets more quickly and produces higher early strength, but its ultimate strength through the curing process will be lower than expected. Una corretta progettazione della miscela può compensare queste condizioni e, in combinazione con misure protettive per prevenire una rapida evaporazione, i possibile versare calcestruzzo di alta qualità ad alte temperature, tenendo conto di fattori aggiuntivi.
- Have sufficient manpower to manage the concrete when it i being poured and for the finihing process.
- Use a large size and amount of coarse aggregate particles if hot weather i likely to occur during the concrete placement. Larger aggregates will minimize the likelihood of concrete shrinkage due to environmental conditions.
- If possible, avoid cementing at noon or in the afternoon.
- Plan an acceptable delivery temperature with the batch plant so that the materials can be cooled by the supplier if necessary. Aggregates can be cooled by spraying water on the stack.
- Consult with a structural engineer or designer to maximize and implement an effective plan to properly control the connection space. When laying concrete in hot climates, control joints should be placed at lower intervals than joints in concrete at low temperatures.
- Use umbrellas or screens to reduce possible harsh conditions.
- Plan to pour the interior plates after all the walls and roofs are built.
- Keep an evaporative retarder ready on-site in case the temperature gets hotter and water i rapidly evaporating.
- Use ice as part of a water-concrete mix or use liquid nitrogen to cool concrete.
- Reduce mixing time po dodaniu wody do mieszanki.
- Consider internal dosing and mixing.
- Do not add water to the premixed concrete unless it i part of the design.
- All necessary equipment should remain covered until the last minute before use. If possible, keep slides, conveyor belts and accessories under a roof and regularly spray them with water.
- When laying the concrete on the slab, moisten the substrate first.
- Use cold water to moisten the side shapes of the plates or walls.
- Do not begin finihing concrete while water i still on the surface.
- Use the correct curing method to allow the concrete to harden evenly.
- Get ready to receive and lay concrete.
Be prepared for these heat problems
Quando si versa il calcestruzzo quando fa caldo, i necessario essere preparati a possibili problemi. Due to the temperatures during casting, shrinkage cracks can be quite deep. Thi deep cracking i because the concrete has little capacity to resit shrinkage stresses. Cracks can continue to expand and spread until the contraction stresses are loosened. Other problems can include: