• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.695-702
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• 1998

The purpose of this study is to investigate the mechanical properties of precast concrete cured by accelerated curing methods such as, steam curing method and warm water curing method varing maximum temperature of curing along to the period of curing. Some specimens are cured by accelerated curing method(warm water curing method) and then deposited in the storehouse. The others are deposited in the storehouse directly. All of these are cured until being tested to compare these two group's mechanical characteristics for each period 3days, 7days, 28days. The goal of this comparison is to estimate the efficiency of accelerated curing method in the case of precast concrete stocked in the field or warehouse for a long term and to make guide line for factory manager to make a economical products of concrete of a good quality. We can conclude some guide lines 1) It is not efficient to cure concrete with accelerated method at higher than 80℃. 2) The continuing of curing period more than 36hr makes damage to concrete in using accelerated curing method. 3) The strength revelation of concrete cured by accelerated curing methods, added rice husk ash more delayed than OPC concrete done but the strength of maximum value is higher than OPC concrete. 4) It is not efficient to use accelerated curing method in the case of storing the products for more than 7days in the aspect of mechanical properties.

• Structural Engineering and Mechanics
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• v.58 no.6
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• pp.989-999
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• 2016

Moist curing of concrete is a time consuming procedure. It takes minimum 28 days of curing to obtain the characteristic strength of concrete. However, under certain situations such as shortage of time, weather conditions, on the spot changes in project and speedy construction, waiting for entire curing period becomes unaffordable. This situation demands early strength of concrete which can be met using accelerated curing methods. It becomes necessary to obtain early strength of concrete rather than waiting for entire period of curing which proves to be uneconomical. In India, accelerated curing methods are used to arrive upon the actual strength by resorting to the equations suggested by Bureau of Indian Standards' (BIS). However, it has been observed that the results obtained using above equations are exaggerated. In the present experimental investigations, the results of the accelerated compressive strength of the concrete are used to develop the regression models for predicting the short term and long term compressive strength of concrete. The proposed regression models show better agreement with the actual compressive strength than the existing model suggested by BIS specification.

• Magazine of the Korea Concrete Institute
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• v.8 no.4
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• pp.141-148
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• 1996

The pulished works on Accelerated Curing Effect were generally performed around from 1960 to 1970th century for 18 to 24 hours - total curing periods. It is not possible to define the effect of temperature rise because those results were obtaine mainly by using the manually operated steam-curing tank. Thus, it may not be available to apply those data immediately on the domestic PC wall production line. The testing specimens were made from the standard mix proportion according to those of domestic PC factories to establish a basic data for the Accelerated Curing Effect. The experimental tests were conducted according to the conditions of each sub-curing periods. By comparing the results of compression tests on de-molded and 28-day water-curing specimens, we find that the most effective curing condition to obtain more than the required design strength after 28 day of water curing may be as follows: the presteaming period does not affect seriously and less than$30^{circ}C/hr$- the rate of temperature rise andless than $82^{circ}C$ - maximum temperature are necessary. It seems that post-curing procedure is very important factor to increase the effect of accelerated curing.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.04a
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• pp.107-111
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• 1996

The testing specimens were made from the standard mix proportion according to those of domestic PC factories to establish a basic data for the Accelerated Curing Effect. The experimental tests were conducted according to the conditions of each sub-curing periods. By comparing the results of compression tests on de-molded and 28-day water-curing specimens, we find that the most effective curing condition to obtain more than the required design strength after 28 days of water curing may be as follwings; the presteaming period does not affect seriously and less than $30^{\circ}C$/hr-the rate of temperature rise and less than $82^{\circ}C$ - maximum temperature are necessary. It seems that post-curing procedure is very important factor to increase the effect of accelerated curing.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.4
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• pp.3931-3942
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• 1975

This study was conducted to investigate the strength of soil cement for varied curing temperatures (0,10,20,30,40,50,60$^{\circ}C$) and cement content (3,6,9,12%) in four cement-stabilized soils (KY: sand, MH: sand, SS: sandy loam, JJ:loam). The experimental results obtained from unconfined compressive strength tests were as follows: 1. According to increase of curing temperature as 30,40,50, and 60$^{\circ}C$, the unconfiened compressive strength of soil cement increased, the rate of increase in the early curing period was large, and around 120 hours was suifficient curing time to complete hardening. 2. The strength at 10$^{\circ}C$ decreased to the rate of 30 to 40 percent than that of 20$^{\circ}C$ while the strength at 0$^{\circ}C$ was very small, strength of soil cement increased in cold weather unless that the temperature was below 0$^{\circ}C$ 3. The average maximum temperature, about 30$^{\circ}C$ during July and August in Korea may be recommended for a optimum construction period to increase the strength of soil cement. 4. Accelerated curing time that strength was equivalent to 28-Day norma1 curing decreased in accordance with the increase of curing temperature, and also accelerated curing decreased the effect of cement content. Accelerated curing that strength was equivalent to 28-day normal curing for soil cement of cement content 9% and temperature 60$^{\circ}C$ was 45 hours; KY, 50 hours: MH, 40 hours; SS, 34 hours; JJ. 5. According to the increase of the percent passing of No. 200 sieve, accelerated curing times became shorter to become the required stength. 6. Relation between accelerated curing times and normal curing days was showeda linear of which slope decreased in accordance with the increase of curing temperature, it may be expressed as follows: (1). 30$^{\circ}C$ t=3.6d+6(r=0.97) (2). 40$^{\circ}C$ t=3.2d-5.1(r=0.95) (3). 50$^{\circ}C$ t=2.1d-4.0(r=0.93) (4). 60$^{\circ}C$ t=1.4d+4.0(r=0.90) in which t=accelerate curing time. d=normal curing day. 7. Accelerated curing time that the strength was equivalent to 35kg/$\textrm{cm}^2$ which was the strength of cement brick was 96 hours at temperature 30$^{\circ}C$ to SS 9%, and 120 hours at temperature 50$^{\circ}C$ to JJ 9%, Consequently, a economic soil cement brick may be made in future.

• Magazine of the Korean Society of Agricultural Engineers
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• v.19 no.1
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• pp.4312-4322
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• 1977

In order to investigate the effect of the water content and the accelerated curing on the strength of the soil-cement mixtures, laboratory test of soil cement mixtures was performed at five levels of water content, four levels of accelerated curing temperatures, three levels of normal curing periods, and six levels of accelerated curing time. Also this study was carried out to investigate the effect of grain size distribution of 21 types of soils on the strength of soil-cement mixtures at four levels of cement content and three levels of curing time. The results are summarized as follows: 1. Optimum moisture content increased with increase of the cement content, but maximum dry density was changed ununiformly with cement content. Water content corresponding to the maximum strength was a little higher than the optimum moisture content along the increase of cement content. 2. In molding the specimens with the optimum moisture content, the maximum strength appeared at the wet side of the optimum moisture content. 3. According to increase of curing temperature as 30, 40, 50, and 60$^{\circ}C$, unconiiend compressive strength of soil-cement mixtures increased, the rate of increase at the early curing period was large, and approximately 120 hours was suifficient to harden soil-cement mixtures completely. 4. The strength of soil-cement mixtures at the curing temperature of 10$^{\circ}C$ decreased at the rate of 30 to 50 percent than at the curing temperature of 20$^{\circ}C$, and the strength of soil-cement mixtures at the curing temperature of 0$^{\circ}C$ increased a little with increase of curing time. 5. Although the strength of soil-cement mixtures seemed to be a little affected by the temperature difference between day time and night, it was recommended that reasonable working period was the duration from July to August of which average maximum temperature of Korea was approximately 30$^{\circ}C$. 6. Accelerated curing time corresponding to the normal curing time of 28-day was shorten with increase of curing temperature, also it was a little affected by the cement. Accelerated curing time that the strength of soil-cement mixtures for the cement of 9 percent and the curing temperature of 60was shorten with increase of curing temperature, also it was a little affected by the cement. Accelerated curing time that the strength of soil-cement mix- tures for the cement of 9 percent and the curing temperature of 60$^{\circ}C$ was 45 hours at the KY sample, 50 hours at the MH, 40 hours at the SS, and 34 hours at the JJ respectively. 7. Accelerated curing time was depended upon the grain size distribution of soil, it decreased with increase the percent passing of No. 200 sieve. 8. Relationship between the normal curing times and the accelerated curing times showed that there was a linear relationship between them, its slope decreased with increase of curing temperature. 9. The most reasonable soil of the soil-cement mixtures was the sandy loam which was a well graded soil. Assuming the base of road requiring 7-day strength of 21 kg/$\textrm{cm}^2$ being used, the soil-cement mixtures could be obtained with adding 6 percent of cement in such a sails S-7, S-8, S-9, S-10, S-11, S-12, S-13. 10. The regression equation between the 28-day and the 7-day strength was obtained as follow; q28=1.12q7,+6.5(r=0.96).

• KCI Concrete Journal
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• v.12 no.1
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• pp.79-89
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• 2000

This research developed an accelerated curing processe for cellulose fiber reinforced cement composites using vigorous reaction between carbon dioxide and cement paste. A wet-processed cellulose fiber reinforced cement system was considered. Carbonation curing was used to complement conventional accelerated curing. The parametric study followed by optimization investigation indicated that the carbonation curing can enhance the productivity and energy efficiency of manufacturing cellulose fiber reinforced cement composites. This also adds environmental benefits to the technical and economical advantages of the technology.

• International Journal of Concrete Structures and Materials
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• v.4 no.1
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• pp.9-15
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• 2010

Silica fume is a common addition to high performance concrete mix designs. The use of silica fume in concrete leads to increased water demand. For this reason, Florida Department of Transportation (FDOT) allows only a 72-hour continuous moist cure process for concrete containing silica fume. Accelerated curing has been shown to be effective in producing high-performance characteristics at early ages in silica-fume concrete. However, the heat greatly increases the moisture loss from exposed surfaces, which may cause shrinkage problems. An experimental study was undertaken to determine the feasibility of steam curing of FDOT concrete with silica fume in order to reduce precast turnaround time. Various steam curing durations were utilized with full-scale precast prestressed pile specimens. The concrete compressive strength and shrinkage were determined for various durations of steam curing. Results indicate that steam cured silica fume concrete met all FDOT requirements for the 12, 18 and 24 hours of curing periods. No shrinkage cracking was observed in any samples up to one year age. It was recommended that FDOT allow the 12 hour steam curing for concrete with silica fume.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.10a
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• pp.119-123
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• 1995

This paper presents an accelerated-curing method by the war water method and discusses how these methods can be adapted for regular quality control and quality assurance of concret. Accelerated strength test data can be used for estimating the furture stength, e.g. the 28-day strength. An accelerated-curing method to predict the 28-day strength of concrete from 1-day warm water-cured test results was evaluated in the laboratory and the field. For these evaluations test are performed for 1845 standard specimens from 123 different batches of concrete. The results of this study the equation applicable universally with resonable accuracy are presented for estimating the potential strength of concrete by the warm water-curing method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2020.11a
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• pp.33-34
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• 2020

𝛾-dicalcium silicate (𝛾-C₂S) is characterized by its strong carbonation reactivity and has the prospect to be utilized as a building material with the added benefit of CO₂ capture. This paper aims to point out the impact of 𝛾-C₂S on the microstructure characteristics and mechanical properties of GGBFS paste, and mortar samples. The compressive strength of 𝛾-C₂S added GGBFS cement mortar is higher compared to without 𝛾-C₂S in accelerated carbonation (AC) up to 14 days of curing but once the curing duration is increased, there is no significant improvement in compressive strength. This study suggests that 𝛾-C₂S can capture the atmospheric CO₂ (mostly generated from cement and metallurgy industries) and utilized in construction.