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International Concrete Abstracts Portal

Showing 1-5 of 97 Abstracts search results

Document: 

21-008

Date: 

September 1, 2021

Author(s):

Yifeng Ling and Peter Taylor

Publication:

Materials Journal

Volume:

118

Issue:

5

Abstract:

Although internal vibration has been widely implemented in concrete pavements, reports about concrete deterioration caused by improper vibration have been emerging. This study investigates the transmission of vibration energy, water movement, and air movement in concrete under vibration to provide the experimental basis for a better understanding of vibration in different concrete mixtures. An innovative experimental method was developed to measure energy transmission in concrete. The mixtures varied by air content, slump, and water-reducing admixture addition and were prepared to test the vibration energy, water absorption, and the air-void system for a range of vibrator frequencies. The vibration energy transferred through the mixture generally displayed a linear rise, then a slight drop, and, finally, stability, indicated by both measurements of transferred energy and voltage demand of the vibrator. The magnitude of vibration energy transferred through the mixtures increased with an increasing slump. For all samples tested, water appeared to move away from the vibrator, most markedly with an increasing frequency. There is a clear indication of air movement to the surface of the concrete in all tested samples.

DOI:

10.14359/51732981


Document: 

20-219

Date: 

July 1, 2021

Author(s):

R. V. M. Toffolo, T. K. Moro, D. H. Santos, L. C. B. Costa, J. C. Mendes, and R. A. F. Peixoto

Publication:

Materials Journal

Volume:

118

Issue:

4

Abstract:

This work evaluates the technical feasibility of a roller-compacted concrete (RCC) pavement with complete replacement of natural aggregates by electric arc furnace slag (EAFS) or basic oxygen furnace slag (BOFS). The methodology includes, initially, the processing of the slags, and physical, chemical, and environmental characterization of the natural and slag aggregates. Subsequently, concrete mixtures were designed, and the compaction at optimum moisture was performed. Finally, the behavior of specimens under service and their mechanical performance were evaluated. Results show that both EAFS and BOFS enhance the RCC’s compressive strength and modulus of elasticity. The RCC produced with BOFS aggregates presented some expansibility due to its high contents of chemically active finer-than-75-µm materials and higher porosity. The EAFS aggregate was stable in durability analysis. In conclusion, through optimal mixture proportions and using compatible energy compression, it is viable to produce pavements with EAFS steelmaking slag in efficient, economical, and environmentally friendly manners. BOFS also showed promising results but requires further investigation.

DOI:

10.14359/51732791


Document: 

20-140

Date: 

March 1, 2021

Author(s):

Quang Tran and Jeffery Roesler

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

The concrete final set time (tf) is influenced by the concrete mixture and ambient conditions. Rapid measurement in the laboratory or field is difficult because of wet sieving or access and device coupling limitations. A non-contact, one-sided ultrasonic testing system (UTS) has been developed to monitor leaky Rayleigh wave (LR-wave) signals emitting from the specimen surface with an array of non-contract microelectromechanical systems (MEMS) receivers. A new ultrasonic set time (tUS) parameter was defined based on the initiation time of the LR-wave energy curve. The UTS technique implemented in the laboratory determined the tUS of multiple mortar mixtures to be between 270 and 1335 minutes. The tUS for the mortars were consistent with tf by ASTM C403 penetration resistance when the transmitter’s incident angle was set at 12 degrees. Different incident angles (12 to 60 degrees) influence the signal quality and tUS. The non-contact UTS was deployed on three concrete pavement sections and produced tf of 210, 266, and 289 minutes.

DOI:

10.14359/51729328


Document: 

20-098

Date: 

March 1, 2021

Author(s):

Mengesha A. Beyene and Richard C. Meininger

Publication:

Materials Journal

Volume:

118

Issue:

2

Abstract:

The mechanism of alkali-carbonate reaction (ACR) is still controversial. ACR distress in concrete has been described as an increase in volume caused by the crystallization of brucite following dedolomitization. In this study, the cause of concrete distress in reported ACR-damaged concrete pavements was investigated, and it was determined that alkali-silica reaction (ASR) was the cause of the damage. Optical microscopy and scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS) analyses identified ASR gel extending from reactive aggregates into the paste, X-ray elemental mapping confirmed the composition of the gel, and EDS determined the amount of each element in the ASR gel spectra. Silica in the form of cryptocrystalline-microcrystalline quartz was found in the matrix of reactive aggregates and was the source of reactive silica. The test results confirmed that ASR caused the damage to the primary concrete pavements and present the first case ever reported in the United States in which ASR is the main cause of concrete damage in concrete made from carbonate aggregate exhibiting a classic texture and composition cited for ACR.

DOI:

10.14359/51729327


Document: 

19-477

Date: 

January 1, 2021

Author(s):

Solomon Debbarma and G. D. Ransinchung R. N.

Publication:

Materials Journal

Volume:

118

Issue:

1

Abstract:

The paper aims to address the use of natrojarosite, an industrial waste material, as a partial replacement to portland cement in roller-compacted concrete pavement (RCCP) mixtures. Natrojarosite particles were used in proportions of 0%, 5%, 15%, 20%, and 25%, by weight of cement, respectively. It was observed that the optimum moisture content increases as the natrojarosite replacement level increases but were still lower than that of the control mixture. Meanwhile, the maximum dry density was found to be enhanced until 15% of natrojarosite replacement level, and subsequently, the strength and transport properties were also found to be improved. Scanning electron microscope images confirmed that the natrojarosite particles acted as a filler material which improved the transition zone and pore structure of the hydrated matrix. Contrarily, higher replacement levels showed reduction in the concrete strength and higher susceptibility to acid attack primarily due to the high sulfur trioxide content in the natrojarosite particles. Nevertheless, natrojarosite of up to 15% could be used to improve the strength and durability of RCCP. Moreover, the use of natrojarosite particles would lower the consumption of portland cement and eliminate the disposal issue of the harmful natrojarosite waste.

DOI:

10.14359/51728281


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