• Advances in concrete construction
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• v.9 no.1
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• pp.33-41
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• 2020

In this study, polyethylene glycol (PEG) and polyacrylamide (PAM) have been used as self-curing agents to produce self-curing concrete (SC). Compressive strength, ultrasonic pulse velocity (UPV), bulk electrical resistivity, chloride ion penetrability, water permeability, and main microstructural characteristics were examined under different curing regimes, and compared to those of the control concrete mixture with no self-curing agents. One batch of a control mixture and one batch of a SC mixture were air-cured in the lab to act as non-water-cured samples. The water curing regimes for the control mixture included continuous water curing for 3, 7, and 28 days and periodical moist curing using wetted burlap for 3 and 7 days. Curing regimes for the SC mixtures included 3 days of water curing and periodical moist curing for 3 and 7 days. SC mixtures showed better microstructure development and durability performance than those of the air-cured control mixture. A short water curing period of 3 days significantly improved the performance of the SC mixtures similar to that of the control mixture that was water cured for 28 days. SC concrete represents a step towards sustainable construction due to its lower water demand needed for curing and hence can preserve the limited water resources in many parts of the world.

• Advances in concrete construction
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• v.5 no.3
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• pp.271-288
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• 2017

This paper aims to investigate the effects of replacing cement with ground granulated blast furnace slag (GGBFS) in self compacting concrete in the fresh and hardened state. The performance of SCC in moderate climate is well investigated but few studies are available on the effect of hot environment. In this paper, the effect of initial water-curing period and curing conditions on the performance of SCC is reported. Cement was substituted by GGBFS by weight at two different levels of substitution (15% and 25%). Concrete specimens were stored either in a standard environment (T=$20^{\circ}C$, RH=100%) or in the open air in North Africa during the summer period (T=35 to $40^{\circ}C$; R.H=50 to 60%) after an initial humid curing period of 0, 3, 7 or 28 days. Compressive strength at 28 and 90 days, capillary absorption, sorptivity, water permeability, porosity and chloride ion penetration were investigated. The results show that the viscosity and yield stress are decreased with increasing dosage of GGBFS. The importance of humid curing in hot climates in particular when GGBFS is used is also proved. The substitution of cement by GGBFS improves SCC durability at long term. The best performances were observed in concrete specimens with 25% GGBFS and for 28 days water curing.

• Computers and Concrete
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• v.33 no.2
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• pp.205-216
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• 2024

Self-Curing Self Compacting Concrete (SCSCC), is a special concrete in contemporary construction practice aimed at enhancing the performance of structural concrete. Its primary function is to ensure a sufficient moisture supply that facilitates hydration along with flow, particularly in the context of high-rise buildings and tall structures. This innovative concrete addresses the challenges of maintaining adequate curing conditions in large-scale projects, maintaining requisite workability, contributing to the overall durability and longevity of concrete structures. For implementing such a versatile material in construction, it is imperative to understand the stress-strain (S-S) behaviour. The primary aim of this study is to develop the S-S curves for TCSCSCC and compare through experimental results. Finite element (FE) analysis based ATENA-GiD was employed for the numerical simulation and develop the analytical stress-strain curves by introducing parameters viz., grade of concrete, tie diameter, tie spacing and yield strength. The stress ratio and the strain ratios are evaluated and compared with experimental values. The mean error is 1.2% with respect to stresses and 2.2% in case of strain. Finally, the stress block parameters for tie confined SCSCC are evaluated and equations are proposed for the same in terms of confinement index.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.573-578
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• 2002

We carried out the feasibility study of super early self compacting concrete having the characteristics of 1 day demoulding without steam curing, high flowable concrete with self compacting, high strength and high durability etc. Here, We test and selected by several methods using high early cement with and without admixtures for the condition of super early strength self compacting concrete's manufacture (SSCC). We sucessed to meet at the goal of SSCC with 30∼35N/㎟ in 1 day, without steam curing and with slump flow about 60-65cm and suggest various concrete products to apply the developed SSCC for practical use in factory and in site place

• Advances in concrete construction
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• v.7 no.4
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• pp.277-288
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• 2019

The formulation of self-compacting concretes (SCC) and the study of their properties at the laboratory level were currently well mastered. The aim of this work is to characterize SCC under hot climatic conditions and their effects on the properties of fresh and hardened SCC. Particularly, the effect of the initial wet curing time on the mechanical behavior such as the compressive strength and the durability of the SCCs (acid and sulfate attack) as well as the microstructure of SCCs mixtures. In this study, we used two types of cement, Portland cement and slag cement, three water/binder (W/B) ratio (0.32, 0.38 and 0.44) and five curing modes. The obtained results shows that the compressive strength is strongly influenced by the curing methods, 7-days of curing in the water and then followed by a maturing in a hot climate was the optimal duration for the development of a better compressive strength, regardless of the type of binder and the W/B ratio.

• Advances in concrete construction
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• v.5 no.4
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• pp.359-375
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• 2017

This paper presents a study of the properties and behavior of self-compacting concretes (SCC) in the hot climate. The effect of curing environment and the initial water curing period on the properties and behavior of SCC such as compressive strength, ultrasonic pulse velocity (UPV) and sorptivity of the SCC specimens were investigated. Three Water/Binder (W/B) ratios (0.32, 0.38 and 0.44) have been used to obtain three ranges of compressive strength. Five curing methods have been applied on the SCC by varying the duration and the conservation condition of SCC. The results obtained on the compressive strength show that the period of initial water curing of seven days followed by maturation in the hot climate is better in comparison with the four other curing methods. The coefficient of sorptivity is influenced by W/B ratio and the curing methods. It is also shown that the sorptivity coefficient of SCC specimens is very sensitive to the curing condition. The SCC specimens cured in water present a low coefficient of sorptivity regardless of the ratio W/B. Furthermore, the results show that there is a good correlation between ultrasonic pulse velocity and the compressive strength.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.05a
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• pp.79-84
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• 2002

We carried out the feasibility study of super early self compacting concrete having the characteristics of 1 day demoulding without steam curing, high flowable concrete with self compacting, high strength and high durability etc. Here, We test and selected by several methods using high early cement with and without admixtures for the condition of super early strength self compacting concrete's manufacture (SSCC). we sucessed to meet at the goal of SSCC with 20-35N/mm$^2$ at 1 day, without steam curing and with slump flow about 60-65cm. We continue to search the effectual conditions of SSCC's manufacture by changing mix designs, several of admixture (superplasticizer, stabilising agent), slag, fly ash, high early cement and apply the products for practical use.

• International Journal of Highway Engineering
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• v.19 no.1
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• pp.11-19
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• 2017

PURPOSES : The purpose of this study is to verify the property of self-healing, and to propose an appropriate duration for wet curing of bridge deck concrete overlays. METHODS : In this study, reinforced bars were inserted into concrete molds in order to prevent brittle fracture and induced cracks in the concrete resulting from indirect tension mode. The induced time of concrete cracking was 3 to 7 days, following which the concrete specimens were cured in water. The resulting concrete crack width was measured using image analysis equipment. Additionally, the self-healing tests were performed using the following three mixtures: OPC, SFC, and LMC. RESULTS : Concrete mixtures with crack widths of $150{\mu}m$ or lower were completely healed by Day 28. Hydrates of crack fills were found to be the calcium carbonate. CONCLUSIONS : The cement-based mixtures exhibit properties of self-healing. Considering these properties, it is necessary to increase the curing duration of concrete overlays for bridge decks.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.763-766
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• 1999

The objective of this study was to investigate the influence of low temperature curing on resistance of freezing and thawing of self-compacting concrete placed in cold weather regions. The experimental study results indicated that the self-compacting concrete incorporating ground granulated blast-furnace slag showed good resistance to freezing and thawing, and the self-compacting concrete cellulose viscous agent had relatively poor resistance to freezing and thawing.

• Journal of the Korea Concrete Institute
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• v.23 no.2
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• pp.219-224
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• 2011

In this study, a piezoelectric smart sensor that can be embedded inside of concrete structures is developed to investigate the early stage of concrete curing. A waterproof coating is used to protect the piezoelectric sensor from moistures of concrete mixture. Also, a mortar case is utilized to encapsulate the sensor to protect it from impact loads. To estimate the strength of concrete, a self-sense guided-wave actuated sensing technique is applied. In the guided wave, its velocity is varied according to the mechanical properties of concrete such as modulus of elasticity. Because modulus of elasticity directly affects the strength of concrete, the guidedwave's velocity also affects the concrete strength development. To verify the feasibility of using the proposed approach, the smart sensor was embedded into a 100MPa concrete cylinder and the self-sense guided wave is continuously measured throughout the curing process. The measurements showed that the propagation time (TOF) of the measured guided waves gradually decreased as the curing age increased. Especially, at the early age of the curing process, the variation of the TOF was very significant. Furthermore, the results showed that there is a linear relationship between the TOF of the self-sense guided waves and the strength of concrete existed. It is safe to conclude that the proposed approach can be used very effectively in monitoring of the strength development of high strength concrete structures.