Steam curing is advantageous where early strength gain in concrete is important or. To resolve it, this paper developed a new steam cured concrete incorporating fly ash and a chemical activator gypsum. Steam cured selfconsolidating concrete and the effects of. Curing has a strong influence on the properties of hardened concrete. Steamcured concrete is widely used to manufacture prefabricated units of highspeed railway foundation structure such as girder and track slab. Except for steam curing system, the specimens of which were tested at the age of three days, for all other curing conditions, the compression tests were performed at the age of 28 days. Curing means water at the surface of the concrete is retained to allow the.
Evaluation of factors pertaining to delayed ettringite formation in steam cured precast concrete members johnson mak, kirk vessalas, paul thomas, centre for built infrastructure research, university of technology, sydney. Twenty mixes with various combinations of portland cement, fly ash fa. Optimization of steamcuring regime for highstrength, self. Precasters using steamcuring methods should take proper measures to monitor temperature and curing cycles as well as ensure there are no leaks in the enclosure. Furthermore, steam curing reduced the static modulus of elasticity of concrete compared to that of the water cured concrete.
The appearance of cracks on specimens from this type concrete was detected after 49 days of drying exposure. Conventional curing and lowpressure steam curing are two of the more common methods of curing precast concrete products. Researcharticle influence of steam curing method on the performance of concrete containing a large portion of mineral admixtures mengyuanli,qiangwang,andjunyang. Curing must be undertaken for a useful period of time if concrete is to attain its potential strength and durability. Conventional curing involves the continuous saturation of the concrete surface with water for a specified length of time, starting as soon as the concrete is no longer susceptible to damage at ambient temperatures. Outline of steam curing steam curing is a method for accelerated curing whereby concrete is cured in hot steam to obtain the required strength early. A comparison was made between the impact of raising the thermostatic temperature and the impact of prolonging the thermostatic time on the performance of steam cured concrete containing a large portion of fly ash fa or ground granulated blast furnace slag ggbs by analysing the form removal strength, chemically combined water content, reaction degree, strength development, chloride. Steamcured concrete incorporating mineral admixtures. Pdf properties of steam cured recycled aggregate fly ash. The various methods of steam curing are briefly described and preliminary laboratory data on the effect of low pressure curing are given.
Curing should begin as soon as the concrete stiffens enough to prevent marring or erosion of the surface. However, the negative effect of steam curing diminished as the recycled. Effect of gypsum on strength development of steamcured. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed. Harold deatherage results of tests carried out to investigate the causes of earlyage cracking reported in some precast, prestressed, steamcured structural members are reported. Effect of steam curing on the strength of concrete by. Concrete that has been subjected to steam curing is called steam cured concrete. Apr 2006 data sheet curing of concrete curing is the process of controlling the. Besides, some researchers suggested that the excellent dimensional stability of the co 2cured concrete was resulted from the significant productions of caco 3, which is well crystallized and exhibits a better dimensional stability than the main hydration products, csh, in the steamcured concrete blocks shi et al. Influence of steam curing method on the performance of concrete.
The need for adequate curing of concrete cannot be overemphasized. Numerical modeling of concrete beams under serviceability conditions with a discrete crack approach and noniterative solution. Curing may be applied in a number of ways and the most appropriate means of curing may be dictated by the site or the construction method. The use of fly ashes for cementreplacement purposes, especially in high volumes, decreases rate of early strength development of the steam curing concrete. The time delay between the mixing of the concrete and the beginning of steam curing. Steam curing of portland cement concrete at atmospheric pressure richard r. Effect of gypsum on strength development of steamcured concrete. Materials free fulltext optimization of steamcuring.
Curing is essential in the production of concrete to have the desired properties. The scr of steam cured conventional concrete and microconcrete of two compositions with compressive strength of approximately 20 mpa was studied. The problem with steam cured cement is that in the long term, the cement may be weaker. Steam curing is a process for accelerating the early hardening of concrete and mortars by exposing it to steam and humidity. Pdf the influence of steam curing on earlyage compressive. Mechanical properties of steam cured highstrength steel.
In general, the results reveal that selfconsolidating concrete containing 15% limestone filler, steam cured at 55c, 70c and 82c, exhibited similar or superior mechanical and transport properties as well as long term durability performance compared to similar. In the present paper, serial macromicroexperiments were carried out to investigate the. This paper explores the potential benefits of steam cured concrete, particularly on mixes incorporating mineral admixtures. Curing begins immediately after placement and finishing so that the concrete may develop the desired strength and. Concrete strength test results from 3 prestressing plants utilizing steam curing were evaluated by aci standard 214 recommended practice for the evaluation of compression test results of field concrete for the purpose of establishing a simple procedure to aid the production of uniform, high quality, steam cured concrete for prestressing. More civil engineering related videos will be uploaded in future. Concrete is a composite material consisting of cement, sand and water in suitable proportions. Influence of steam curing method on the performance of. Curing is necessary if concrete is to achieve its intended function over the design life of the structure whereas. The dynamic mechanical property of steam cured concrete is one of the key properties affecting service performance of highspeed railway foundation structure. Get the most out of concretes many excellent benefits with strict attention to proper curing. The various methods of steam curing are briefly described and preliminary laboratory data on the. Pdf influence of steam curing cycle on compressive strength.
Curing means water at the surface of the concrete is retained to allow the concrete to hydrate to a point where it has a strong, durable structure. The precast concrete industry uses steam curing procedures to quickly produce structural members. The optimum bfs replacement ratio varied between 50 and 60% in terms of the compressive strength developed in steam cured hsc both early and during longterm aging. The steamcuring cycle was set based on the peak temperature, and the duration for. In general, concrete that has been steam cured and then air dried is not as good as concrete that has been continuously fog cured or even fog cured for 7 days. Researcharticle the role of phosphorus slag in steamcured. Even three days water curing increases this figure to 60%, whilst 28 days water curing increases it to 95%. The influence of thermostatic time and thermostatic temperature on the form removal strength of steamcured concrete is presented in table 4. The strength of a concrete specimen prepared, cured and tested under specified conditions at a.
The strength and durability of concrete will be fully developed only if it is properly cured. Effect of steam curing on initial strength development of mortar ijet. Duration of time that concrete is allowed to cool after the steam has been shut off and prior to removing the enclosure. Johnson project hr40 of the iowa highway research board for presentation at the 4lst annual meeting of the highway research board, washington, d.
Steam curing of concrete magazine of concrete research. It was observed that the conventional concrete had the highest scr. Us2880101a manufacture of steamcured lightweight concrete. Steam curing at atmospheric pressure is one of the techniques for obtaining high early strengths in concrete especially in precast concrete production. The most commonly adopted curing techniques are steam curing at. Apr 07, 2020 the problem with steam cured cement is that in the long term, the cement may be weaker.
Steam cured cement, concrete, and mortar products are stronger at the outset than traditionally cured products, but they are more likely to fracture, crumble, and develop other problems later in their useful lives. Under the steam curing condition, the high temperature will greatly enhance. Steam cured concrete is widely used to manufacture prefabricated units of highspeed railway foundation structure such as girder and track slab. Keeping concrete moist is therefore, a most effective way of increasing its ultimate strength. It features its short demolding period, natural cure without using steam, low production cost, high strength and high sound isolating and heat. This paper developed a new high performance steamcured concrete hpsc incorporating grade i fly ash fa i and a chemical activator, which can be used for high speed railway precast elements. Concrete physical property development at early ages. Steam curing of portland cement concrete at atmospheric.
Kripanarayanan portland cement association skokie, illinois a systematic procedure is presented for predicting the material behavior of different weight concretes and the time. It has been found that the curing system greatly influences the concrete strength. Researcharticle the role of phosphorus slag in steamcured concrete jinliuanddongminwang schoolofchemicalandenvironmentalengineering. The chemical interaction between cement and water binds the aggregate. This type of system is most commonly used for precast concrete products where standard products are manufactured in the factory and the turnaround time of the formwork is very quick. Harold deatherage results of tests carried out to investigate the causes of earlyage cracking reported in some precast, prestressed, steam cured structural members are reported. Steam curing of concrete at atmospheric pressure has the advantage of. The method laid down in this standard may be used for qualitycontrol purposes, or for the. Instituto politecnico nacionalciidir unidad oaxaca, hornos 1003, oaxaca, mexico. These curing cycles will vary with the type of product being cured. Non steam cured foamed concrete plate contains lowalkali cement 4060 portions, flyash 2540 portions, fiber 0.
In the present paper, serial macromicroexperiments. Significance of curing of concrete for durability of. It is suitable for curing horizontal surfaces such as floors, roof slabs. Basic properties and utilization of steamcured concrete using. Steam curing of portland cement concrete at atmospheric pressure.
The scr of steam cured conventional concrete and micro concrete of two compositions with compressive strength of approximately 20 mpa was studied. The optimum bfs replacement ratio varied between 50 and 60% in terms of the compressive strength developed in steamcured hsc both early and during longterm aging. The design and construction of these members is required to comply with relevant statutory requirements, including the steam curing procedure, which is the focus of this report. Ponding on flat surfaces, such as pavements and floors, concrete can be cured by ponding. To resolve it, this paper developed a new steamcured concrete incorporating fly ash and a chemical activator gypsum. Feb 01, 2018 this video is the explainer video related to concrete technology subject in civil engineering. Steam curing of concrete concrete curing clc curing. Concrete that has been subjected to steam curing is called steamcured concrete. Curing begins immediately after placement and finishing so. Nonsteam cured foamed concrete plate contains lowalkali cement 4060 portions, flyash 2540 portions, fiber 0.
Steam curing of concrete concrete curing clc curing youtube. Twenty mixes with various combinations of portland cement, fly ash fa, slag and silica fume sf were investigated. High performance steamcured concrete for railway precast elements. Effect of steam curing on the important properties of concrete. Steam cured selfconsolidating concrete and the effects of limestone filler mohammad a. Properties of steam cured recycled aggregate fly ash concrete. These techniques are especially useful in the prefabrication industry, wherein high early age strength enables the removal of the formwork within 24 hours, thereby reducing the cycle time, resulting in costsaving benefits. Accelerated curing is any method by which high early age strength is achieved in concrete. Earth or sand dikes around the border of the concrete surface can retain a pond of water.
The use of aci standard 214 in the quality control of steam. Concrete mixtures with a lower wb ratio and higher replacement ratios of bfs up to 60% exhibited higher compressive strength than their counterparts. Curing is defined as maintenance of a satisfactory moisture content and temperature in the concrete for a period of time immediately following placing and finishing so that the desired properties may develop. Aqel doctor of philosophy civil engineering department university of toronto 2016 abstract the purpose of this thesis is to determine the effect and the mechanisms associated with. Pdf influence of steam curing cycle on compressive. This video is the explainer video related to concrete technology subject in civil engineering. Figure 1 shows an example of temperature hysteresis of steam curing.
This paper explores the potential benefits of steamcured concrete, particularly on mixes incorporating mineral admixtures. Research was also conducted to determine steam curing effect on drying shrinkage, dynamic modulus, weight change to 6 months age, and modulus of rupture. This technique enables early removal of shuttering and facilitates early vacating of the. Influence of steam curing method on the performance of concrete containing a large portion of mineral admixtures. The gain of earlyage compressive strength in steamcured.
The 28day strengths of the steam cured concrete with a 3hour delay av eraged 73 percent of the moistcured concrete strengths, with a cv of 9. Experiments were conducted to investigate the mechanical properties at early and. Us2880101a us58745756a us2880101a us 2880101 a us2880101 a us 2880101a us 58745756 a us58745756 a us 58745756a us 2880101 a us2880101 a us 2880101a authority us united states prior art keywords concrete steam weight magnesia mixture prior art date 19560528 legal status the legal status is an assumption and is not a legal conclusion. Expired lifetime application number inventor ulfstedt leo torsten. During steam curing, the curing temperature should not be increased or decreased by more than 22 c to 33 c per hour, depending on the type of concrete, and the. High performance steamcured concrete for railway precast. Precasters using steam curing methods should take proper measures to monitor temperature and curing cycles as well as ensure there are no leaks in the enclosure. Scope this test shall be used to determine the acceptability of steam cured reinforced concrete pipe with fly ash.
Stem cured concrete tennessee research and creative exchange. Fresh concrete will be plastic so that it can be moulded to any desired shape and compacted to. The dynamic mechanical property of steamcured concrete is one of the key properties affecting service performance of highspeed railway foundation structure. Effect of steam curing on the strength of concrete by using. Steam curing of concrete at ordinary pressure manufacture. Curing is the maintenance of a satisfactory moisture content and temperature in concrete for a period of time immediately following placing and finishing so that the desired properties may develop fig. Humes precast has a long history of providing quality steam cured precast concrete girder solutions for numerous projects across australia. This paper investigates the properties of steam cured recycled aggregate concrete rac, in an attempt to determine the optimum conditions of the steamcuring cycle for rac, and incorporating high early strength cement hesc. Curing is the maintaining of an adequate moisture content and temperature in concrete at early ages so that it can develop properties the mixture was designed to achieve. Effect of aggregate on shrinkage crackresistance of steam.
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