The durability decreases due to higher permeability. The frost and weathering resistances are decreased. The rate of carbonation increases. The surfaces are coated with sand and dust and it leads to lower the abrasion resistance. Methods of curing Following two factors are considered while selecting any mode of method of curing: The temperature should be kept minimum for dissipation of heat of hydration.
The water loss should be prevented. Several specialized curing techniques are employed in the modern construction work, but the most commonly employed methods of curing are as follows: Ponding with water.
Covering concrete with wet jute bags. Covering concrete with water-proof paper of polythelene sheets and holding it in position. Intermittent spraying with water and continuous sprinkling of water. Applying curing compounds. Related Post. There are three ways to cure concrete: either we add water to the surface to replace the water that is evaporating or we seal the concrete to prevent the water from evaporating in the first place or we do both.
Note that adding water to the surface is NOT adding water that will be worked into the concrete mix--that would increase the water-cement ratio of the surface concrete and weaken it, ruining all our curing efforts.
You need to think about initial curing when the bleed water is evaporating too rapidly to keep the surface wet prior to initial set. Traditionally that has been specified at greater than 0. Many mixes today bleed at much lower rates than this, so if there is less bleed water then the evaporation limit needs to be set lower-more like 0.
The best approach for decorative concrete is to try to alter conditions so you don't need to do initial curing: block the wind, keep the sun off the concrete, get cooler concrete.
If that's not possible, fogging just enough to keep the surface damp is possible, but the simplest approach is to use evaporation retardant.
This chemical can be sprayed on to form a thin membrane on the surface that prevents the water from evaporating. It completely dissipates during finishing operations. Keep some of this around for dry windy conditions. After concrete is placed, the concrete increases in strength very quickly for a period of days. Water curing can be done after the slab pour by building dams with soil around the house and flooding the slab. The enclosed area is continually flooded with water.
Ideally, the slab could be water cured for 7 days. Consider planning your job to pour at the end of the week, build berms, then flood over the weekend.
You get the benefit of water curing without losing too much time in the schedule. Get Job Leads Today! About Us Free Newsletters. Scofield Co. Great for interior and exterior. Leaves no topical residue. Industra-Seal A Protects and fortifies concrete against moisture damage. Easily applied with spray equipment. Copyright ConcreteNetwork. Forms provide the adequate protection against moisture loss. It inform us in which place the Curing Compound suitable.
Giridhar, this answer is from our technical department. Thank you for contacting NPCA with your inquiry. It is recommended that you contact the design engineer for the project to determine the specified compressive stripping strength minimum at 12 hours. We have changed our release oil and checked our raw materials, this isnt happening with all the pieces, our rubber molds seem to be ok, but our Hdo wood molds seem to have the issue.
I have experienced this before and after asking around one of the guys told me it was due to over vibration ie leaving the vibrator in one spot for too long. We are applying steam curing in precast panels in Iraq. We have started this procedure back in June and continuing until now. Are these two factors the reason for getting so low strength?
What can we do to improve this condition? My friend noticed some big cracks in his concrete and wants to have it replaced. You mentioned that concrete cures to maturity over time but the rate of curing depends on the mix design and the curing environment. Do all companies use the same type of mix? It seems beneficial for him to contact a concrete company to see what his best options are.
Thank you Derek for the comment. I agree it would be beneficial for your friend to contact a company near him for advice.
Guys, we are setting up a factory in Nigeria producing interlocking paving stones, our hottest temperature is 84 degree.
What sort of curing solution would you advice we get? Thank you for your question. They will be able to help you with purchasing the right curing compounds or connect you with someone closer to your factory. We would recommend also contacting the Standards Organisation of Nigeria. They should have more information about what types of curing compounds are permitted in your area. Please feel free to contact us if you have any further questions and we will try our best to answer them or direct you to someone who can.
Ceramics bigger than recommended size should not be used Pay attention about mixing ratios of epoxy resin based adhesives. Your email address will not be published. Save my name, email, and website in this browser for the next time I comment.
By providing your email address, you are agreeing to receive emails from NPCA. By Evan Gurley To cure or not to cure?
Fogging or spraying involves the use of a relatively inexpensive nozzle that atomizes the water into a fog-like mist, increasing the humidity of the air above the concrete surface and reducing the rate of evaporation of the concrete surface. Concrete must be kept continually moist. Fogging is very effective when the ambient temperature is well above freezing and humidity is relatively low.
Water from fogging should not be worked into the surface and should be removed or allowed to evaporate before finishing. Fogging or spraying is an effective way to minimize plastic shrinkage cracking but obviously requires a good source of water and close attention. Natural coverings. When burlap, cotton, straw or other moisture-retaining fabrics are used, they should be kept saturated at all times and free of deleterious oil, excessive dirt, abrasive metals substances.
As soon as the freshly placed concrete has hardened adequately, wet coverings may be applied. Coverings should be kept consistently moist to avoid cycles of wetting and drying that can lead to surface crazing or cracking.
While a seemingly simple procedure, coverings are said to be one of the most effective curing methods. Reducing the loss of mixing water from the freshly placed exposed concrete surfaces plastic or polyethylene sheeting, membrane-forming curing compounds, internal moist curing with forms left in place Plastic sheeting. Polyethylene sheeting is an effective way to cure concrete by retaining moisture and heat on freshly cast concrete.
Plastic film used as a moisture barrier for curing concrete should comply with ASTM C, 3 which specifies the minimum thickness of the film to be 0. Polyethylene sheeting should also be applied to the concrete as soon as it has hardened sufficiently.
The sheeting should be overlapped approximately 18 in.
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