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Home > Publications > International Concrete Abstracts Portal
The International Concrete Abstracts Portal is an ACI led collaboration with leading technical organizations from within the international concrete industry and offers the most comprehensive collection of published concrete abstracts.
Showing 1-5 of 30154 Abstracts search results
December 1, 2023
Stephen Wright and Laura Redmond
Exposure to high temperature is well known to cause concrete
degradation and lead to compressive strength loss. However, most
research focuses on concrete exposed to high temperatures for more
than 1 hour, and the available predictive equations for concrete
strength loss due to heat exposure do not consider the effects of
concrete thermal mass or account for variation in concrete thermal
properties. This work proposes a methodology to create a predictive
equation for the compressive strength loss in concrete exposed
to heat. The proposed method leverages concrete temperature data
from transient thermal analyses of concrete specimens correlated
to results from experimental testing. The resulting equation from
the analyzed data set predicted compressive strength loss with a
root-mean-square error (RMSE) of 1.35% absolute error of the
measured strength loss, and the maximum absolute underprediction
in strength loss was 12.4% across all 26 cases examined.
Ben Wang, Abdeldjelil Belarbi, Mina Dawood, and Bora Gencturk
This paper presents the findings of an experimental study on
the corrosion performance of both conventional and corrosionresistant steel reinforcements in normal-strength concrete (NC), high-performance concrete (HPC), and ultra-high-performance concrete (UHPC) columns in an accelerated corrosion-inducing environment for up to 24 months. Half-cell potential (HCP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) methods were used to assess the corrosion activities and corrosion rates. The reinforcement mass losses were directly measured from the specimens and compared to the results from electrochemical corrosion rate measurements. It was concluded that UHPC completely prevents corrosion of reinforcement embedded inside, while HPC offers higher protection than NC in the experimental period. Based on electrochemical measurements, the average corrosion rate of mild steel and high-chromium steel reinforcement in NC in 24 months were, respectively, 6.6 and 2.8 times that of the same reinforcements in HPC. In addition, corrosion-resistant steel reinforcements including epoxycoated reinforcing bar, high-chromium steel reinforcing bar, and stainless-steel reinforcing bar showed excellent resistance to corrosion compared to conventional mild steel reinforcement. There was no active corrosion observed for epoxy-coated and stainless steel
reinforcements during the 24 months of the accelerated aging; the
average corrosion rateS of high-chromium steel was 50% of that of
mild steel in NC based on the electrochemical corrosion measurements; and the average mass loss of high-chromium steel was 47% and 75% of that of mild steel in NC and HPC, respectively. The results also showed that the LPR method might slightly overestimate the corrosion rate. Finally, pitting corrosion was found to be the dominant type of corrosion in both mild and high-chromium steel reinforcements in NC and HPC columns.
Othman AlShareedah and Somayeh Nassiri
Pervious concrete is a stormwater management practice used in the
United States, Europe, China, Japan, and many other countries. Yet
the design of pervious concrete mixtures to balance strength and
permeability requires more research. Sphere packing models of
pervious concrete were used in compressive strength testing simulations using the discrete element method with a cohesive contact law. First, three mixtures with varied water-cement ratios (w/c) and porosities were used for model development and validation. Next, an extensive database of simulated compressive strength and tested permeability was created, including 21 porosities at three w/c. Analysis of the database showed that for pavement applications where high permeability and strength are required, the advised porosity is 0.26 to 0.30, producing average strengths of 14.4, 11.1, and 7.7 MPa for w/c of 0.25, 0.30, and 0.35. The model can guide the mixture design to meet target performance metrics, save materials and maintenance costs, and extend the pavement life.
Hongbo Zhu, Yilu Zhang, Hongxiang Gou, Liang Ren, and Qing Chen
To improve the added application value of an industrial waste stone
powder (SP), the optimizing mechanism of SP for the structure and
composition of hydrothermal synthetic hardened cement stone was
investigated in this paper. Cement was partially replaced by SP,
silica fume (SF), or ground-granulated blast-furnace slag (GGBS),
and then the microstructure with different SP content was tested
through X-ray diffraction, thermogravimetric analysis (TG-DTG),
mercury intrusion porosimetry (MIP), and scanning electronic
microscopy. The findings indicate that the incorporation of SP in
autoclaved products significantly enhanced compressive and flexural
strengths. As the proportion of SP in cement was increased, a
corresponding increase in the content of tobermorite within autoclaved cement mortar was observed. This increase in tobermorite concentration results in an initial rise followed by a subsequent decline in both compressive and flexural strengths. The maximum compressive and flexural strengths were achieved at an SP content of 15%. In addition, the mechanical strength was further improved by adding SP+GGBS or SP+SF. The strengthening mechanism of SP reveals that the change in the ratio of calcium and silicon ions (C/S) caused by SP in the sample was conducive to the formation of tobermorite and strength increase. Meanwhile, an increase in the quantity and a decrease in the crystal size of tobermorite were observed with an increase in the content of stone powder, resulting in a more compact microstructure of the sample. Moreover, the mechanical strength of cement composites doping SP+GGBS or SP+SF was further improved through superposition effects of SP and GGBS or SF with high activity. Currently, it is mainly applied to pipe pile products, and the strengthening effect of SP increases its use value. Meanwhile, the study of SP strengthening mechanism has laid a theoretical foundation for its application in high-strength autoclave and improved the relevant theory.
J. F. Munoz, C. Balachandran, A. Shastry, R. Mulcahy, J. M. Robertson, and T. S. Arnold
The periodic evaluation of the alkali-silica reaction (ASR) susceptibility of aggregates is a key strategy to eliminate the risk of ASR development in transportation infrastructure. A reliable and practical accelerated ASR test is paramount to improve the frequency and efficiency of the aggregate evaluation campaign. This paper assesses the suitability of the new Turner-Fairbank Highway
Research Center ASR susceptibility test (T-FAST) as a costeffective
tool to evaluate aggregates. Thirty-eight aggregates of varying mineralogies, including carbonates, were characterized using the T-FAST and AASHTO T 380. The results were compared with historic AASHTO T 303 data. The T-FAST accurately classified the reactivity of the aggregates and was identified as the most sensitive among the three accelerated tests. Additionally, the combination of the T-FAST results with the possibility of accurately determining the alkali thresholds of the aggregates provided a broader understanding of the conditions conducive to triggering ASR in the field.
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