Concrete is an integral material in any and every construction and home improvement project. However, if concrete sets too quickly, it can cause problems like reduced strength and cracks. Therefore, you should order the right concrete mix delivery and follow the rules when pouring concrete. Follow below to know the causes and fixes for concrete that is setting too quickly.
Causes Of Concrete Setting Quickly
Warm Weather
Temperature affects the concrete curing process. Warm weather leads to faster evaporation, so concrete sets quickly. On the other hand, cold temperatures cause slower setting of concrete. Therefore, it’s critical to control the temperature when pouring, setting, and curing concrete because it directly impacts the strength of the structure.
Sunlight
As temperature affects the setting time of concrete, sunlight also does because it increases the temperature and quickens the rate of water evaporation from the concrete. This leads to concrete setting more quickly than expected. So, if sunlight brings extreme temperature changes in the region you’re working, then schedule your project at night, create a shade, and order a concrete mix that’s right for the weather conditions.
Low Humidity
Another weather condition that speeds up concrete setting time is low humidity. It also makes the evaporation process rapid, and makes the concrete lose water content more quickly.
Wind
Wind also accelerates the evaporation process, so if you’re pouring concrete in windy conditions, prepare the concrete mix accordingly to avoid it from setting prematurely and cracking.
The Concrete Mix’s Temperature
The ideal temperature for a concrete mix is 50°F to 90°F. However, in hot weather conditions, the concrete mix may become hotter, and when hot concrete is poured, it may set more quickly than you would want. To avoid this problem, store the concrete mix in a temperature-controlled environment.
If you’re ordering ready-mix concrete, you can choose suppliers who have insulated trucks. If not, make sure that the plant is near you so the transit time is reduced.
Low Water-Cement Ratio
If you’re using a low water-cement ratio intentionally, you want the structure to be strong and durable. However, this practice also reduces the workability of concrete because it sets quickly. So, plan your project accordingly and use superplasticizers to increase the workability of concrete without affecting its water-cement ratio if you’re using a low water-cement ratio on purpose.
However, if the water-cement ratio is low by mistake, you can try ways to fix this:
Add water gradually but ensure that the consistency of the concrete is optimum and the water-cement ratio doesn’t exceed your ideal figure. For normal concrete, a water-cement ratio between 0.4 to 0.6 is considered ideal.
Moreover, if you’re going to site-mixed concrete, make sure that you mix the concrete properly. Many concrete problems occur due to poor mixing, so ensure proper mixing.
If you ordered ready-mix concrete and it had a lower water-cement ratio, check if you ordered the right mix design and consult the supplier. For future projects, choose a reputable concrete supplier.
Accelerating Admixtures
As the name suggests, accelerating admixtures are used for reducing the setting time of concrete. If used improperly, they will make concrete set too quickly, which will lead to poor finishing, strength issues, and cracks.
Using accelerators is helpful in many conditions, like in winter, but in the wrong weather conditions, they will only create problems. So, use accelerators according to the weather and your requirements.
Overmixing Concrete
Overmixing concrete is a known poor concrete mixing practice that can cause various issues, such as segregation, faster setting time, reduced strength, and the concrete becoming difficult to work with.
On-site concrete mixing can lead to overmixing sometimes, so if you want a perfect concrete mix for your project, a better option is to order ready mix concrete delivery Potomac.
How To Fix Concrete That Is Setting Too Quickly?
Add Retardants
One of the best ways to fix concrete that has reduced workability is by adding retardants. They are the opposite of accelerators as they increase the setting time of concrete, helping you pour and finish concrete before it becomes difficult to do so.
Retarding admixtures are commonly used in hot and windy weather conditions to keep the heat and wind from affecting the setting time of concrete and attain the desired results. They are also preferred because they usually don’t affect the strength of concrete, whereas other methods like adding water or cement can be difficult and can alter the concrete’s strength.
Change Your Schedule
If the concrete setting issues are due to the weather conditions like hot and dry weather, you can change your schedule to a cooler time of the day, such as the morning or late night.
Adjust The Water-Cement Ratio
If the cause of the problem is a low water-cement ratio, you can simply add more water. However, be careful not to overdo it, otherwise, the concrete will become too thin, leading to pores and reduced compressive strength. Make sure to keep the water-cement ratio between 0.4 to 0.6.
Avoid Overmixing Concrete
Overmixing not only reduces the setting time of concrete, but it also reduces the strength and durability of concrete. To avoid overmixing, you should mix for the required duration only, which is usually 3 to 5 minutes. Moreover, use the right mixer and tools for proper mixing. Also, look for visual clues to know when to stop. So, keep an eye out for uniform color and texture.
Pre-Pour Concrete Techniques
You can dampen the surface on which you will pour concrete (sub-grade) to keep the concrete from hydrating quickly. This is recommended if you’re hot weather concreting.
Post-Pour Concrete Techniques
If you don’t want to change the concrete mix, and the cause of concrete’s premature setting is low humidity and warm weather, you can try post-pour concrete techniques like misting the surface regularly, using wet coverings, applying curing sheets, and rescheduling the project to morning or night.
Use Cement With Standard Gypsum Content
Gypsum is a small but integral part of cement. Cement has tricalcium aluminate (C3A). It is what makes the cement set quickly. Because of this, gypsum is added to cement as a retardant to keep the cement from setting prematurely.
Various cement manufacturers add gypsum in various percentages. To avoid problems, use cement with a standard gypsum content of 3-5%. Lower gypsum content will lead to rapid setting of concrete, while higher gypsum in cement will cause the concrete to take more than the required time for setting and curing.
Use Fly Ash Or Slag Cement
This is a prevention tip as adding fly ash or slag to an already prepared concrete mix can be difficult. Fly ash and slag are added with cement to slow down the hydration process of concrete in windy or hot weather. You can replace 15-35% of structural concrete with fly ash to increase the workability of concrete and keep it from setting too quickly. A benefit of using fly ash is that it, in fact, increases the strength of concrete.
Conclusion
Premature setting of concrete reduces its strength and causes flaking and cracks. You should determine the cause of your concrete setting quickly to apply the right solution. Plus, hire a trusted ready-mix concrete supplier Rockville who ensures on-time delivery of properly mixed concrete according to the industry standards and your requirements.