Proper Curing Way To increase concrete strength very quickly for 3-7 days. The concrete structure is moist cured for 7days is about 50% stronger than uncured concrete. as we know curing plays an important role in strength developments and durability of concrete.
Curing with water takes place immediately after concrete placing and finishing, and it involving maintenance of desired moisture and temperature climate conditions. Properly cured concrete has an adequate amount of moisture for continued hydration and developments of strength, volume stability, and resistance power, scaling resistance.
The main components which need to be taken care of are moisture, heat and time during the curing process. Curing mistakes may reason for concrete failures. to cracks many reasons right from concrete mix designs, properties of the material used, mixing, placing and compaction, curing procedure and many more.
Concrete Curing Methods, Uses
There are many misconceptions about concrete curing. on many occasions, curing period of concrete elements, plinth beams, plasters, brickwork proper curing is considered as one of the significant reasons for concrete failures in columns, beams, slabs, pavements. Evident in the form of racks that are easily noticeable. process of maintaining a satisfactory moisture content and a favorable temperature in concrete during the period immediately following placement, so that hydration of cement may continue until the desired properties are developed to a sufficient degree to meet the requirement of service.
Curing can be described as keeping the concrete moist and warm enough so that the hydration of cement can continue. many ways available for curing concrete. The chemical interaction between cement and water binds the aggregate. Fresh concrete will be plastic so that it can be molded to any desired shape and compacted to form a dense mass. 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. as one experimental case, on a tight schedule water cure for 3 days as this achieves approximately 80% of the benefit of water curing for 7 days. so better to cure 3-7 days for the better curing process.
Benefits of Curing Concrete:
To prevent the concrete to dry out prematurely due to solar radiation, thermal reaction, climate conditions, and wind. This prevents plastic shrinkage of concrete. This helps the development of impermeable, crack free and durable concrete.
It helps to maintain the concrete temperature by allowing the hydration process. safe zone temperature from inside. The hydration process requires water to carry on and releases heat from all corners. Curing helps the concrete to harden and bond with internal materials and reinforcement. It helps to prevent damage to the bond between concrete and reinforcement due to vibration and impact.
The vertical member like a column, in particular, is one of the most victimized RCC elements which must be carefully cured, as the entire load from the slabs and beams are supported by columns and transferred to the foundations.
Definition of Curing: Curing is the process in which the concrete is kept moist to protect it from loss of moisture due to atmospheric temperature and hydration reaction.
When to start curing of concrete for better strength?:
The best time to start the curing of concrete depends upon the material used in the site, evaporation rate of moisture from the concrete.Water is to be applied for a few days over the concrete surface soon after its setting because the hydration reactions between cement and water continue for a more extended period due to which hardening of the concrete takes place. curing is classified as three main steps. initial curing, Intermediate curing, and Final curing process.
On the day concrete is placed and compacted, bleeding of water occurs and rises through the surface of concrete due to the settlement of concrete. The concrete rate curing time depends upon many factors including concrete mix properties, admixtures use, depth or thickness of concrete, methods of compaction of concrete. Drying state of concrete stats, then initial curing of concrete is required to minimize the moisture loss and prevent plastic shrinkage cracks to the concrete before and during finishing operations.
Intermediate curing is done when the concrete surface finishing operations have carried out before the final set of concrete. Curing of concrete must begin as soon as possible after placement & finishing and must continue for a reasonable period as per the relevant standards. Curing also ensures to maintain an adequate temperature of concrete at an early age. Maintaining the proper temperature also plays an important role in concrete as mentioned, it should not be cooler than 50C. It is recommended to keep concrete moist for 28 days. Nowadays Due to lack of time, the curing can be achieved by following modern techniques in 14-20 Days. But it is always recommended to keep concrete moist for at least 14 days.
The curing process is designed primarily to keep the concrete moist by controlling the loss of moisture from the body of concrete. curing duration depends upon the size of the concrete structural member and the temperature and moisture conditions of surroundings. The duration of the curing of concrete depends on the grade & type of cement, mix proportion, desired concrete strength, shape, and size of the concrete member and environmental & exposure conditions. The duration may vary from a few days to a month. at least 7 days from the date of placing, in case of Ordinary Portland Cement (OPC) and at least 10 days when mineral admixtures or blended cement are used.
Main functions of curing
Maintaining mixing water in concrete during the early hardening process
Reducing the loss of mixing water from the surface of the concrete
Accelerating strength gain using heat and additional moisture
Water curing is done by spraying or sprinkling water over the concrete surface to ensure that the concrete surface remains continuously moist. Plinth beam, column, slab, wall whatever cover it. This prevents the moisture from the body of concrete from evaporating and contributes to the strength gain of concrete. in many places ponding, sprinkling, fogging, wet coverings most common and inexpensive methods for curing flat surfaces such as floor slabs, flat roofs, pavements, and other horizontal surfaces.
Wet coverings such as burpless, gunny bags, mats, rugs, etc. may be used to maintain water on the concrete surface by completely covering the surface immediately after the concrete as a set. Straw sprinkled with water regularly can be used to cure concrete. Care must be taken when using a straw, as dry straw can fly away if the wind velocity is very high Fogging minimizes moisture loss during and after placing and finishing of concrete. Prevent the loss of the mixing water from concrete by sealing its surface.
The precast concrete items are normally immersed in curing tanks for a certain duration. Pavement slabs, roof slab, etc. are covered underwater by making small ponds. cured by spraying water. In some cases, wet coverings such as wet gunny bags, hessian cloth, jute matting, straw, etc., are wrapped to a vertical surface for keeping the concrete wet. Due to the chemical reaction between cement and water in concrete releases heat which requires water to complete hydration. In summer 50% of water is evaporated. Plastic sheet may be transparent or colored depending upon the ambient temperature prevailing during that particular season.
Concrete blankets also available for better curing. Concrete insulation blankets are used to cover and insulate concrete surfaces subjected to freezing temperatures during the curing period. One of the best methods to cure. The concrete should be hard enough to prevent surface damage when covering with concrete blankets.
Time – 3-7 Days
Temperature – 50-100 F
Moisture – Saturated at all times
What is the reason behind the curing of concrete?
What is the minimum curing time for cement concrete?
What are the methods of concrete curing?
What methods to ensure sufficient moisture for curing concrete?
Concrete is kept moist by providing water through
Continuous water sprinkling
Covering with wet gunnybags
Covering with specially polyethylene bags or other plastic sheeting special made papers
Spraying with a liquid membrane forming curing compound.
Wax emulsions also helps.
What should be the period of curing?
Wet condition for at least 7 days from the date of placing concrete in case of ordinary Portland cement OPC Grade 53 cement mix and at least 10 days where mineral admixtures or blended cements are used.
The period of curing shall not be less than 10 days for concrete exposed to dry and hot weather conditions.