International Concrete Abstracts Portal

Showing 1-5 of 17 Abstracts search results

Document: 

23-036

Date: 

September 1, 2024

Author(s):

Jialuo He, Ayumi Manawadu, Yong Deng, Jie Zhao, and Xianming Shi

Publication:

Materials Journal

Volume:

121

Issue:

5

Abstract:

This laboratory study employed synthesized urea-formaldehyde (UF) microcapsules and polyvinyl alcohol (PVA) microfibers as a self-healing system to improve the durability of concrete in cold climates. The resistance of concrete specimens to rapid freezingand- thawing (F/T) cycles was evaluated by measuring the change of relative dynamic modulus of elasticity (RDM) with respect to the number of F/T cycles. The control specimens (either with or without PVA microfibers) approached the failure state with a reduction of 38% in RDM after being subjected to 54 F/T cycles, whereas the self-healing specimens (either with or without PVA microfibers) remained in a good state with a reduction of approximately 10 to 15% in RDM after 732 F/T cycles. A polynomial regression model was developed to establish the relationship between the RDM and number of F/T cycles, and a three-parameter Weibull distribution model was employed to conduct the probabilistic damage analysis and characterize the relationship between the number of F/T cycles (N) and the damage level (D) with various reliabilities. The results revealed that the benefits of UF microcapsules and PVA microfibers to the frost durability of concrete diminish once the damage level exceeds a certain high level. Based on the Weibull distribution model, the relationships were established and validated between N and D by comparing the experimental data, the predicted data based on the nonlinear polynomial regression model, and the predicted data based on N-D relationships. The field service life of the self-healing concrete was then predictable at any given reliability.

DOI:

10.14359/51742036


Document: 

22-221

Date: 

September 1, 2023

Author(s):

C. F. Hollmann, L. Zucchetti, D. C. C. Dal Molin, and A. B. Masuero

Publication:

Materials Journal

Volume:

120

Issue:

5

Abstract:

Self-healing is a process by which concrete is able to recover its properties after the appearance of cracks, which can improve mechanical properties and durability and reduce the permeability of concrete. Self-healing materials can be incorporated into concrete to contribute to crack closure. This study aims to evaluate the influence of crystalline admixtures and silica fume on the self-healing of concrete cracks. The rapid chloride penetration test was performed on cracked and uncracked samples, from which it was possible to estimate the service life of concretes. The concretes were characterized by tests of compressive strength and water absorption by capillarity. The use of crystalline admixtures did not have a negative influence on concrete properties, but did not favor the chloride penetration resistance. The concrete with silica fume showed the lowest charge passed and highest values of estimated service life.

DOI:

10.14359/51738892


Document: 

21-458

Date: 

January 1, 2023

Author(s):

Duo Zhang and Victor C. Li

Publication:

Materials Journal

Volume:

120

Issue:

1

Abstract:

The built environment is facing an increasing challenge of reducing emissions regarding both embodied and operational carbon. As an ultra-durable concrete, engineered cementitious composites (ECC) reduce the need for repair, thus resulting in a prominent reduction of life-cycle footprints. Herein, a new version of low-carbon ECC was developed for cast-in-place applications by sequestering CO2 through mineralization. Two waste streams were pre-carbonated and incorporated into ECC as fine aggregate and supplementary cementitious material, respectively. At 28 days, the CO2-sequestered ECC exhibited a compressive strength of 32.2 MPa (4670 psi), tensile strength of 3.5 MPa (508 psi), and strain capacity of 2.9%. Multiple fine cracks were distinctly identified, with a residual crack width of 38 μm (0.0015 in.) and a selfhealing behavior comparable to that of conventional ECC. The new ECC sequestered 97.7 kg/m3 (164.7 lb/yd3) CO2 (equivalent to 4.7 wt% of final mixture) and demonstrated a 42% reduction in cradle-to-gate emissions compared to conventional concrete at the same strength level. This study demonstrates the viability of turning waste CO2 gas into durable construction materials and proposes a potential path towards carbon neutrality.

DOI:

10.14359/51737331


Document: 

22-057

Date: 

January 1, 2023

Author(s):

N. P. Kannikachalam, D. di Summa, R. P. Borg, E. Cuenca, M. Parpanesi, N. De Belie, and L. Ferrara

Publication:

Materials Journal

Volume:

120

Issue:

1

Abstract:

This research focuses on the evaluation of the sustainability of recycled ultra-high-performance concrete (R-UHPC) in a life cycle analysis (LCA) perspective, and with reference to a case study example dealing with structures exposed to extremely aggressive environments. This involves the assessment of the self-healing capacity of R-UHPC, as guaranteed by the R-UHPC aggregates themselves. Recycled aggregates (RA) were created by crushing 4-month-old UHPC specimens with an average compressive strength of 150 MPa. Different fractions of recycled aggregates (0 to 2 mm) and two different percentages (50 and 100%) were used as a substitute for natural aggregates in the production of R-UHPC. Notched beam specimens were pre-cracked to 150 μm using a three-point flexural test. The autogenous self-healing potential of R-UHPC, stimulated by the addition of a crystalline admixture, was explored using water absorption tests and microscopic crack healing at a pre-determined time (0 days, 1 month, 3 months, and 6 months) following pre-cracking. Continuous wet/ dry healing conditions were maintained throughout the experimental campaign. The specimens using R-UHPC aggregates demonstrated improved self-healing properties to those containing natural aggregates, especially from the second to the sixth month. To address the potential environmental benefits of this novel material in comparison to the conventional ones, an LCA analysis was conducted adopting the 10 CML-IA baseline impact categories, together with a life cycle cost (LCC) analysis to determine the related economic viability. Both LCA and LCC methodologies are integrated into a holistic design approach to address not only the sustainability concerns but also to promote the spread of innovative solutions for the concrete construction industry. As a case study unit, a basin for collection and cooling of geothermal waters was selected. This is representative of both the possibility offered, in terms of structural design optimization and reduction of resource consumption, and of reduced maintenance guaranteed by the retained mechanical performance and durability realized by the self-healing capacity of R-UHPC.

DOI:

10.14359/51737336


Document: 

21-124

Date: 

March 1, 2022

Author(s):

Nurullah Öksüzer, Özgür Anıl, Gürkan Yıldırım, Alper Aldemir, and Mustafa Sahmaran

Publication:

Materials Journal

Volume:

119

Issue:

2

Abstract:

The main focus of the current research is the development of high-performance fiber-reinforced cementitious composites with large amounts of coarse aggregates without risking deflection-hardening response, and the evaluation of the autogenous self-healing capability of these composites at different scales. The structural performance of cementitious composites exhibiting strain hardening should be known to be used in large-scale specimens. In addition to the studies carried out in small sizes, there is a need to examine the self-healing performances of large-scale specimens. Composite mixtures included different design parameters—namely Class F fly ash-to-portland cement ratio (FA/PC = 0.20, 0.70), aggregate-cementitious materials ratio (A/CM = 1.0, 2.0), addition/type of different fibers (for example, polyvinyl alcohol [P], nylon [N], and hooked-end steel [S] fibers), addition/type of nanomaterials (for example, nanosilica [NS] and nanoalumina [NA]) and inclusion of steel reinforcing bar in tested beams. Small-scale (80 x 75 x 400 mm [3.15 x 2.96 x 15.76 in.]) and large-scale beams (100 x 150 x 1000 mm [3.94 x 5.91 x 39.4 in.]) were produced and considered for performance comparison. Four-point bending tests were performed on different-scale beams loaded by considering different shear span-effective depth ratios (a/d) ranging between 0.67 and 2.00 and 0.67 and 2.96 for small- and large-scale beams, respectively. Autogenous self-healing evaluation was made using different-scale beam specimens subjected to 30-day further cyclic wetting-and-drying curing in terms of changes in microcrack characteristics and recovery in flexural parameters of preloaded beams. Experimental results showed that it is possible to successfully produce concrete with large amounts of coarse aggregates without jeopardizing the deflection-hardening response both at small and large scale. Autogenous self-healing is valid for small- and large-scale beams in terms of crack characteristics/flexural parameters and is found to improve with the increased FA/PC, decreased A/CM, in the presence of nanomaterials, and with the increased fiber amount (regardless of the type). Outcomes of this research are thought to be important because they show the manufacturability of deflection-hardening concrete with large amounts of coarse aggregates at large scale and validate their autogenous self-healing capabilities, which are important for the real-time applicability of such mixtures in actual field conditions.

DOI:

10.14359/51734299


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