Review on the Study of Self Curing Concrete (original) (raw)
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Curing of concrete is maintaining satisfactory moisture content in concrete during its early stages in order to develop the desired properties. « However good curing is not always practical in many cases, therefore the need to develop self-curing agents attracted several researchers ». « The concept of several self-curing agents is to reduce water evaporation from concrete and hence increase the water retention capacity of concrete compared to conventional concrete, the use of self-curing agent is very important from the point view that water resources are getting valuable every day ». This project summarizes various aspects of self-curing of concrete which can be of valuable assistance in adopting good construction practices at site. M25 grade concrete cube specimens prepared based on the standards and availability of materials without and with 30% of flyash and quarry dust replaced as cement and fine aggregate and cubes cured by covering them with a external self-curing compound B...
A Review: Mechanism, Materials and Properties of Self-Curing Concrete
2018
Concrete is most widely used material in the construction industry, it also needs a lot of water for its production, so it is an urgent need of research to minimize the use water to produce concrete. This paper review about the materials used as self-curing agents, mechanism of self-curing and the properties of different type of concrete when subjected to selfcuring method. Self-curing technology is the process which hydrates the cement internally in concrete, no external source needed for curing such as water curing. Mostly concrete goes under extensive self-desiccation, autogenous shrinkage and other properties of concrete can be affected due to improper curing. Different researchers have used different materials such asporous lightweight aggregates, chemicals admixtures, polymers, natural fibers and pozzolanic as self-curing agents in different ways, which have ability to withstand high amount of water. Thesis self-curing agents used as replacement with aggregates and used as inf...
In today's world, concrete is most popular and widely used material in construction sector due to its good compressive strength and durability. Depending upon its usability the mix proportion (cement, fine aggregate, coarse aggregate and water) are prepared to produce plain concrete. Plain concrete needs ambient atmosphere for curing for a minimum period of 28 days in order to attain desired strength. Any laxity in curing will badly affect the strength and durability of concrete. Self-curing concrete is one of the special concretes in mitigating insufficient curing due to human negligence, paucity of water in arid areas, inaccessibility of structures in difficult terrains and in areas where the presence of fluorides in water will badly affect the characteristics of concrete. The present study involves the use of shrinkage reducing admixtures like POLYETHYLENE GLYCOL (PEG 400) as internal curing compound and CUREFREE-C as external curing compound. These curing compounds are used in concrete which helps in self curing and helps in better hydration and hence good compressive strength. They trap the moisture within the structure and prevent it from evaporation (by creating a thin film or by block the pores containing water) which normally occurs due to the hydration process .In the present study, the affect of curing compounds on compressive strength and flexural strength is studied. From the previous studies by various researchers, we vary the percentage of PEG by weight of cement from 0% to 2% as the dosage of internal curing compound and 0.25% of CUREFREE-C by weight of cement was fixed as the dosage of external curing compound The test results were studied both for M25 and M30 mixes .The results shows that PEG 400 and CUREFREE-C could help in self curing by giving strength on par with that of the conventional curing method.
Experimental Investigation of High – Strength Characteristics of Self Curing Concrete
In concrete structures exposed to the ambient air at early ages, the moisture content in concrete decreases due to moisture diffusion. In addition, self-desiccation due to hydration of cement causes an additional decrease of moisture content in concrete at early ages, especially for high-strength concrete. In this study, the internal relative humidity in drying concrete specimens was measured at early ages. Furthermore, the variation of relative humidity due to self-desiccation in sealed specimen was measured. The moisture distribution in low-strength concrete with high water/cement ratio was mostly influenced by moisture diffusion due to drying rather than self-desiccation. In high-strength concrete with low water/cement ratio, however, self-desiccation had a considerable influence on moisture distribution. The results obtained from the moisture diffusion theory were in good agreement with experimental results.
Review on Self Curing Concrete
Now a days water is becoming a scarce material, so there is an urgent need to do research work for reducing the use of water in making concrete and its constructions. Curing of concrete is maintaining satisfactory moisture content in concrete during its early stages in order to develop the desired properties. However good curing is not always practical due to many reasons such as difficult terrain, human negligence and fluorides Therefore the need to develop self-curing agents attracted several researchers. It can perform by several methods such as using lightweight aggregate, super absorbent polymers, chemical agents or shrinkage reducing admixtures.
Self-curing concrete types; water retention and durability
Alexandria Engineering Journal, 2015
Internal curing of concrete by the use of pre-saturated lightweight aggregates or polyethylene-glycol is well established method of counteracting self-desiccation and autogenous shrinkage. This study was carried out to compare among concretes without or with silica fume (SF) along with chemical type of shrinkage reducing admixture, polyethylene-glycol (Ch), and leca as self-curing agents for water retention even at elevated temperature (50°C) and their durability. The cement content of 400 kg/m 3 , silica fume of 15% by weight of cement, polyethylene-glycol of 2% by weight of cement, pre-saturated lightweight aggregate (leca) 15% by volume of sand and water with Ch/ binder ratio of 0.4 were selected in this study. Some of the physical and mechanical properties were determined periodically up to 28 days in case of exposure to air curing in temperature of (25°C) and (50°C) while up to 6 months of exposure to 5% of carbon dioxide and wet/dry cycles in 8% of sodium chloride for durability study. The concrete mass loss and the volumetric water absorption were measured, to evaluate the water retention of the investigated concretes. Silica fume concrete either without or with Ch gave the best results under all curing regimes; significant water retention and good durability properties.
Curing is the name given to the procedure used for promoting the hydration of the cement and consist a control of temperature and moisture movement from the concrete. Curing allows continuous hydration of cement and consequently continuous gain in the strength, once curing stops strength gain of the concrete also stops. Proper moisture conditions are critical because the hydration of the cement virtually ceases when the relative humidity within the capillaries drops below 80%. Proper curing of concrete structures is important to meet performance and durability requirements. In conventional curing this is achieved by external curing applied after mixing, placing and finishing. Self-curing or internal curing is a technique that can be used to provide additional moisture in concrete for more effective hydration of cement and reduced self-desiccation. When concrete is exposed to the environment evaporation of water takes place and loss of moisture will reduce the initial water cement ratio which will result in the incomplete hydration of the cement and hence lowering the quality of the concrete. An experimental study carried out an investigated the use of water-soluble polyethylene glycol (PEG 6000) as self-curing agent. In this study compressive, tensile and flexural strength of self-curing concrete for 7 and 28 days and compared the use of different coarse aggregate (i.e. M35, M45 of normal coarse aggregate and recycled aggregate) and found out optimum strength.
Self Curing Concrete and Its Inherentproperties
Today concrete is most widely used construction material due to its good compressive strength and durability. It is estimated that the present consumption of concrete in the world is of the order of 10 billion tonnes (12 billion tons) every year. Depending upon the nature of work, the cement, fine aggregate, coarse aggregate and water are mixed in specific proportions to produce plain and fresh concrete. The strength and durability of concrete will be fully developed only if it is cured. No action to this end is required, however, when ambient conditions of moisture, humidity, and temperature are sufficiently favorable to curing. Concrete is needed to be provided with moisture for a minimum period of 28 days for good hydration and to attain desired strength. Any laxity in curing will badly affect the strength and durability of concrete. A water/cement ratio of about 0.38 would be required to hydrate all the particles of cement and also to occupy the space in gel pores.
STRENGTH CHARACTERISTICS OF SELF-CURING CONCRETE USING POLYETHYLENE GLYCOL (PEG
Today concrete is most widely used construction material due to its good compressive strength and durability. Depending upon the nature of work the cement, fine aggregate, coarse aggregate and water are mixed in specific proportions to produce plain concrete. Plain concrete needs congenial atmosphere by providing moisture for a minimum period of 28 days for good hydration and to attain desired strength. Any laxity in curing will badly affect the strength and durability of concrete. Self-curing concrete is one of the special concretes in mitigating insufficient curing due to human negligence paucity of water in arid areas, inaccessibility of structures in difficult terrains and in areas where the presence of fluorides in water will badly affect the characteristics of concrete. The present study involves the use of shrinkage reducing admixture polyethylene glycol (PEG 400) in concrete which helps in self curing and helps in better hydration and hence strength. In the present study, the affect of admixture (PEG 400) on compressive strength, split tensile strength and modulus of rupture by varying the percentage of PEG by weight of cement from 0% to 2% were studied both for M20 and M40 mixes. It was found that PEG 400 could help in self curing by giving strength on par with conventional curing. It was also found that 1% of PEG 400 by weight of cement was optimum for M20, while 0.5 % was optimum for M40 grade concretes for achieving maximum strength without compromising workability. Water permeability 2. INTRODUCTION Adequate curing is essential for concrete to obtain structural and durability properties and therefore is one of the most important requirements for optimum concrete performance. Curing of concrete is the process of maintaining the proper moisture conditions to promote optimum cement hydration immediately after placement. With insufficient water, the hydration will not proceed and the resulting concrete may not possess the desirable strength and impermeability. The near surface region of concrete is particularly affected, failing to provide a protective barrier against ingress of harmful agents. Proper curing of concrete structures is important to meet performance and durability requirements. Enough water needs to be present in a concrete mix for the hydration of cement to take place. However, even mix contains enough water, any loss of moisture from the concrete will reduce the initial water cement ratio and result in incomplete hydration of cement especially with the mixes having low water cement ratio. This results in very poor quality of concrete. Proper curing of concrete structures is impotant to meet performance and durability requirements.inconventional curing this is achieved by external curing applied after mixing,placing and finishing. self-curing or internal curing is a technique that can be used to provide additional moisture in concrete for more effective hydration of cement and reduced self-desiccation 2.1 Methods of Conventional Curing Methods of curing concrete fall broadly into the following categories: Ponding or spraying By using covering of wet hessian. Reducing the rate of evaporation of water from concrete surface by covering with a relatively impermeable membrane. Delaying the removal of formwork can also be used to retain some water. Steam curing. 2.2 Difficulties in conventional curing methods For the vertical member it is not possible to keep the surface moist as in case of the flat surfaces. In the places where there is scarcity of water. In the places where manual curing is not possible. A human error may lead to the formation of crack in the member and hence affects strength and durability. 3. Self-curing The ACI-308 Code states that "internal curing refers to the process by which the hydration of cement occurs because of the availability of additional internal water that is not part of the mixing Water." Conventionally, curing concrete means creating conditions such that water is not lost from the surface i.e., curing is taken to happen "from the outside to inside". In contrast, "internal curing" is allowing for curing "from the inside to outside" through the internal reservoirs (in the form of saturated lightweight fine
Effect of Self Curing Agents on Mechanical Properties of Concrete
International Journal of Engineering Research and, 2016
Curing of concrete is the process involved in maintaining satisfactory moisture content and maintain favourable temperature for hydration in concrete so as to develop the desired properties of concrete. However, perfect curing is not always possible in all cases. Self-curing concrete is the type of concrete that can cure itself with its retained moisture content. It is prepared with the addition of certain chemicals as self curing agents. Earlier works conducted on self curing concrete have indicated that these types of concretes have better strength, reduces rate of evaporation from surface, thermal properties, fire resistance, skid-resistance property improves, reduction in autogenous shrinkage, reduced chloride ion penetrability, improvement in freezing and thawing durability as well as the contact zone between aggregate and cement matrix and reduction in micro-cracking which results in better elastic compatibility compared to conventionally cured concretes. In this research paper, the individual effect of curing agents like PEG 4000 & PVA on strength properties by varying the percentage of PEG4000 and PVA by weight of cement 1.0%, 2% and 3% were studied. The study shows that PEG4000 and PVA could help in gaining the strength of conventional curing. It was found that 1% of both PEG4000 and PVA by weight of cement was optimum for M30 grade concrete for achieving maximum strength without compromising workability. The test results showed that self curing concrete is best option in places where water scarcity exists.