Early age strains and self-stresses of expansive concrete members under uniaxial restraint conditions

Semianiuk, Volha; Tur, Viktar; Herrador, Manuel F.

doi:10.1016/j.conbuildmat.2016.11.008

Cited by 33 publications

(29 citation statements)

References 3 publications

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“…Для реализации всех потенциальных позитивных свойств МЗБ с РД, необходимо не только полное связывание алюминатов кальция [16,17] в период, когда структура матрицы находится в упруго-пластичном состоянии [18] и способна деформироваться без образования трещин [19], но и создание оптимальных температурно-влажностных условий твердения [20], исключающих развитие градиента собственных напряжений по сечению твердеющего бетона [21].…”

Section: результатыunclassified

Structure and properties of fine concretes based on composite binders

et al. 2019

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Introduction. Wide introduction of fine concretes in the practice of monolithic building construction is limited by their low crack resistance due to considerable shrinkage. To reduce the shrinkage adverse effect on structure and properties of the fine concretes, it is suggested to use for their preparation composite binders, including expanding sulphoaluminate-based cements. Using the fine concrete with enhanced physical and technical properties improves produceability of construction, reduces labor input of concrete casting and allows building installations of complicated architectural forms. Material and methods. To study processes of fine concrete structure formation and properties, concrete mixes were prepared on the base of medium silica sand, dispersed ash entrainment and expanding additive. Activity of the ash entrainment increased at the expense of mechanical and chemical activation. Dispersity of the particles was monitored by means of laser granulometry. The composite binder was prepared by means of thorough homogenization of the basic CEM 42.5 Portland cement and different sorts of mineral aggregates, including an expanding additive based on calcium sulphoaluminate. Maturing conditions at a certain moisture content were simulated for every composition with subsequent evaluation of concrete performance. Results. Results of the study include effect of different mineral additives distinguishing in mineral composition, dispersivity and degree of hydraulic activity on shrinkage amount and kinetics, fine concrete porous structure parameters and strength. It is understood that amount of expansion has an effect on porous structure characteristics of the fine concrete and its strength performance. The study assessed an influence of maturing conditions on the various-composition fine concrete. A considerable influence of maintaining optimal moisture content during hydration on fine concrete technical properties is committed. Conclusions. It is understood that introduction of up to 10 % of expanding sulphoaluminate-based component in basic Portland cement allows to obtain fine concrete with enhanced crack resistance, impenetrability and longevity.

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Section: результатыunclassified

Structure and properties of fine concretes based on composite binders

et al. 2019

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“…At the same time so-called beam initial «elastic» curvature (that is determined from the accumulated concrete elastic compressive strains distribution) only have an influence on the self-stressed member behaviour under the applied static load in terms of traditional decompression. In contrast with traditional prestressed members in the selfstressed members the values of the beam initial «elastic» curvature are not possible to establish based on the direct strains measurement, but it can be obtained in accordance with the proposed MSDM concept [1,2].…”

Section: Restrained Strains [%]mentioning

confidence: 99%

“…The actual problem for self-stressed concrete members practical design is consisted in the development both of the adequate and universal analytical model for the prediction of the initial stress-strain state obtained at the early age concrete expansion stage and resistance models described such a members behavior subjected to the bending (with and without axial force), shear, etc. Modified strains development model (MSDM) for self-stressed concrete members restrained expansion strains assessment at the anytime interval of the early age selfstressing concrete expansion stage was proposed by the authors [1,2]. The proposed model is extended on the different ratio of the any reinforcement type, and different reinforcement arrangement in the concrete cross-section as well as it allows to calculate early age induced strains for different types of the expansive concretes (shrinkage-compensating, self-stressing).…”

Section: Introductionmentioning

confidence: 99%

Influence of the initial prestressing on the crack resistance of the self-stressed members reinforced with steel and FRP bars

2019

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Fiber reinforced polymer(FRP) bars are widely utilized in the civil engineering practice and characterized by the number of advantages, among them are the following: high strength-to-density ratio; absence of corrosion; resistance to the negative influence of the different aggressive mediums. Nevertheless, a wide practical application of such a bars finds an embarrassment because of the law modulus of elasticity (in the diapason from 30 GPa to 60 GPa), that in its turn lead to the development of the excessive crack opening as well as deflections under the loading. To enhance structural performance of the FRP reinforced concrete members, pretensioning of FRP bars can be considered as a good option. Opposite to the concrete members mechanical pretensioning, physico-chemical method of bars pretensioning based on the self-stressing concrete utilizing is considered. Influence of the controlled initial stress-strain state obtained during early age concrete expansion on the mechanical resistance of the self-stressed concrete members reinforced with both steel and FRP bars was studied. Comparison of the prestressing effectiveness of the self-stressing concrete members with steel and FRP bars was performed. Proposition for effective utilizing of the FRP bars in the self-stressed concrete members was formulated based on results of the presented investigation.

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“…Moreover, several specific high-performance additives have been developed to improve the volume stability of concrete such as expansive agents [2,3], fibres [4,5] and shrinkage reducing admixtures (SRAs) [6]. The shrinkage compensating mechanisms of ettringite (alumina, ferric oxide and tri-sulphate (AFt) phase), a commonly used expansive agent, have not been entirely clarified yet, and there are no guarantees that the manufacturing and subsequent expansion of concrete would ever be desirably controlled even if adequate curing was performed early on [2,[7][8][9]. Nevertheless, the addition of AFt increases the cost and deadweight of concrete.…”

Section: Introductionmentioning

confidence: 99%

Monitoring the Whole Cycle Length Change of Cement Mortar Incorporated with SRA by CMOS Image Sensor

Hao

Yao

Wang

et al. 2020

Sensors

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This paper introduces a new method to measure whole cycle length change non-destructively and continuously using a digital image analysis system. The macroscale length changes of mortars containing different shrinkage-reducing admixture (SRA) dosages (0%, 1%, 2% and 5% by cement weight) were first determined using a complementary metal oxide semiconductor (CMOS) image sensor under alternating dry and wet curing conditions. After that, the length change was calculated using developed digital image processing technology (DIPT) software. After that, several significant conclusions could be drawn by combining with the results of systematic tests of the macroscopic and microscale physical properties of the cement mortar using X-ray diffraction, scanning electron microscopy, mercury intrusion porosimetry (MIP) and nuclear magnetic resonance (NMR) methods. The test results indicated that SRAs exhibited significant effects on the shrinkage inhibition of cement mortars, whereas the shrinkage reduction behaviour was also affected by varying the curing conditions. The MIP and NMR analyses demonstrated that SRAs reduced the irreversible shrinkage of the cement mortars by decreasing the volume percentage of the 3–50 nm pores and promoting the conversion of calcium silicate hydrate gel from an oligomeric to a high polymerization state thereby improving the volume stability of cement mortars.

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Early age strains and self-stresses of expansive concrete members under uniaxial restraint conditions

Cited by 33 publications

References 3 publications

Structure and properties of fine concretes based on composite binders

Structure and properties of fine concretes based on composite binders

Influence of the initial prestressing on the crack resistance of the self-stressed members reinforced with steel and FRP bars

Monitoring the Whole Cycle Length Change of Cement Mortar Incorporated with SRA by CMOS Image Sensor

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