concrete strength
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2022 ◽  
pp. 136943322110651
Author(s):  
Ruiming Cao ◽  
Bai Zhang ◽  
Luming Wang ◽  
Jianming Ding ◽  
Xianhua Chen

Alkali-activated materials (AAMs) are considered an eco-friendly alternative to ordinary Portland cement (OPC) for mitigating greenhouse-gas emissions and enabling efficient waste recycling. In this paper, an innovative seawater sea-sand concrete (SWSSC), that is, seawater sea-sand alkali-activated concrete (SWSSAAC), was developed using AAMs instead of OPC to explore the application of marine resources and to improve the durability of conventional SWSSC structures. Then, three types of fiber-reinforced polymer (FRP) bars, that is, basalt-FRP, glass-FRP, and carbon-FRP bars, were selected to investigate their bond behavior with SWSSAAC at different alkaline dosages (3%, 4%, and 6% Na2O contents). The experimental results manifested that the utilization of the alkali-activated binders can increase the splitting tensile strength ( ft) of the concrete due to the denser microstructures of AAMs than OPC pastes. This improved characteristic was helpful in enhancing the bond performance of FRP bars, especially the slope of bond-slip curves in the ascending section (i.e., bond stiffness). Approximately three times enhancement in terms of the initial bond rigidity was achieved with SWSSAAC compared to SWSSC at the same concrete strength. Furthermore, compared with the BFRP and GFRP bars, the specimens reinforced with the CFRP bars experienced higher bond strength and bond rigidity due to their relatively high tensile strength and elastic modulus. Additionally, significant improvements in initial bond stiffness and bond strength were also observed as the alkaline contents (i.e., concrete strength) of the SWSSAAC were aggrandized, demonstrating the integration of the FRP bars and SWSSAAC is achievable, which contributes to an innovative channel for the development of SWSSC pavements or structures.


2022 ◽  
Vol 2022 ◽  
pp. 1-10
Author(s):  
K. Thirumalai Raja ◽  
N. Jayanthi ◽  
Jule Leta Tesfaye ◽  
N. Nagaprasad ◽  
R. Krishnaraj ◽  
...  

SCC (self-compacting concrete) is a high-flowing concrete that blasts into structures. Many academics have been interested in using an artificial neural network (ANN) to forecast concrete strength in recent years. As a result, the goal of this study is to confirm the various possibilities of using an artificial neural network (ANN) to detect the features of SCC when Portland Pozzolana Cement (PPC) is partially substituted with biowaste such as Bagasse Ash (BA) and Rice Husk Ash (RHA) (RHA). Specialist systems based on the fully connected cascade (FCC) architecture in artificial neural networks (ANN) are used to estimate the compressive toughness of SCC. The research results are confirmed with the forecasting results of ANN utilizing 73 trial datasets of differentiation focus proposals of cement, BA, and RHA containing parameters such as initial setting time (IST), final setting time (FST), and standard consistency. Experiments to determine compressive strength for a wider range of mixed prepositions will result in higher project expenses and delays. So, an expert system ANN is used to find the standard consistency, setting time, and compressive strength for the intermediate mix propositions according to IS 10262:2009. The experimental results of compressive strength for 28 days are considered, in which 70% was used to train the ANN and 30% was utilized for testing the accuracy of the predicted compressive strength for the intermediate mix proposition. Using all of the datasets, the number of hidden layers used for compressive strength prediction for intermediate mix proposal is determined in the first step. The compressive strength for the intermediate mix preposition was identified in the second phase of the research, using the number of hidden layers determined in the first phase. The results were validated using the correlation coefficient (R) and root mean square error (RMSE) obtained from ANN, resulting in an acceptance range of 97 percent to 99 percent.


Materials ◽  
2022 ◽  
Vol 15 (1) ◽  
pp. 335
Author(s):  
Raju Sharma ◽  
Jeong-Gook Jang ◽  
Jong-Wan Hu

The use of phase-change materials (PCM) in concrete has revealed promising results in terms of clean energy storage. However, the negative impact of the interaction between PCM and concrete on the mechanical and durability properties limits field applications, leading to a shift of the research to incorporate PCM into concrete using different techniques to overcome these issues. The storage of clean energy via PCM significantly supports the UN SDG 7 target of affordable and clean energy. Therefore, the present study focuses on three aspects: PCM type, the effect of PCM on concrete properties, and connecting the outcome of PCM concrete composite to the United Nations sustainable development goals (UN SDGs). The compensation of reduction in strength of PCM-contained concrete is possible up to some extent with the use of nanomaterials and supplementary cementitious materials. As PCM-incorporated concrete is categorized a type of building material, the large-scale use of this material will affect the different stages associated with building lifetimes. Therefore, in the present study, the possible amendments of the different associated stages of building lifetimes after the use of PCM-incorporated concrete are discussed and mapped in consideration of the UN SDGs 7, 11, and 12. The current challenges in the widespread use of PCM are lower thermal conductivity, the trade-off between concrete strength and PCM, and absence of the link between the outcome of PCM-concrete composite and UN SDGs. The global prospects of PCM-incorporated concrete as part of the effort to attain the UN SDGs as studied here will motivate architects, designers, practicing engineers, and researchers to accelerate their efforts to promote the consideration of PCM-containing concrete ultimately to attain net zero carbon emissions from building infrastructure for a sustainable future.


2022 ◽  
pp. 136943322110523
Author(s):  
Sarwar Hasan Mohmmad ◽  
Mehmet Eren Gülşan ◽  
Abdulkadir Çevik

This study examines the punching shear and deflection performance of 16 Geopolymer concrete (GC) two-way slabs subjected to monotonic and cyclic loading by considering the reinforcement material, percentage of reinforcement, type of concrete and the concrete grade. The tested specimens indicated that the crack patterns at the failure and failure modes were almost similar regardless of the type of reinforcement or their ratio. Moreover, the slabs reinforced by fibre-reinforced polymer (FRP) bars exhibited a lower punching capacity than those strengthened by steel bars, even for similar reinforcement ratios. In addition, the results showed that upon increasing the concrete strength and reinforcement ratio, a higher punching shear capacity and lower deflections were obtained under cyclic and monotonic loading. In addition, the punching shear performance of GC slabs was found to be better than that of ordinary concrete (OC), even though both were reinforced by the basalt FRP (BFRP) bar. However, the ultimate load capacity of the slabs was reduced as a result of cyclic loading according to the capacity of the same specimen, resulting from static loading. However, the reduction is very low for slabs reinforced with FRP slabs. Further, the slabs reinforced by FRP had a better fatigue performance compared with slabs reinforced by steel bars with respect to cyclic loading. The results of the tests were also used to evaluate the accuracy of the available punching shear capacity equations.


PCI Journal ◽  
2022 ◽  
Vol 67 (1) ◽  
Author(s):  
Isabella Zapata ◽  
John Corven ◽  
Seung Jae Lee ◽  
David Garber

This paper presents the results of analytical studies on the connection between piles and pile caps or footings. Two nonlinear finite element analysis software packages were used to investigate the behavior of the connection itself and the impact of connection assumptions on the overall behavior of different sensitive structures such as simple spans with uneven span lengths, segmental box girders with fixed pier tables, and straddle bents with temperature loading. Results show that the behavior of the connection is affected by variables such as pile size, pile embedment length, pile cap concrete strength, interface reinforcement, and distance between the edge of the pile and the edge of the pile cap. The study also demonstrated that significant moment can develop even with shallow pile embedment lengths. The assumed level of fixity between the pile and pile cap was found to significantly influence the behavior of some of the bridges investigated in this study.


Author(s):  
Carla Cavalcante Araújo ◽  
Gibson Rocha Meira

abstract: Periodic inspections in reinforced concrete structures are important to be carried out to assess their state of conservation. In this scenario, non-destructive tests can be a suitable option since destructive tests are invasive and may be difficult to be performed in some cases. Considering this option, correlations between non-destructive test parameters and the concrete properties to be analyzed are useful tools that make easier the structure inspection. In the present work, correlations between the compressive strength (fc) and splitting tensile strength (ft) and surface electrical resistivity (ρ) of concretes were studied. Brazilian concretes of six different mixtures were analyzed at five different ages and correlation curves between strength properties and surface electrical resistivity of concrete were obtained, which are represented by the general relationships fc= 14.18·ln(ρ) + 18.43 and ft = 0.69·ln(ρ) + 2.15 for compressive strength and splitting tensile strength, respectively. In addition, a general curve considering literature data and results from this work was proposed to represent the relationship between compressive strength and surface electrical resistivity - fc = 11.89·ln(ρ) + 18.90.


2022 ◽  
Vol 2148 (1) ◽  
pp. 012039
Author(s):  
Junlong Yang ◽  
Ziru Wang ◽  
Jizhong Wang

Abstract This article presents a durability study of carbon fiber-reinforced polymer (CFRP) partially wrapped seawater sea-sand concrete (SSC) columns exposed to natural seawater to explore the effect of exposure duration on the long-term performance of the specimens. Thirty-two cylinders were wrapped with CFRP jackets and exposed to different times of wet-dry cycles (up to 360 days) in an outdoor simulated marine environment. Test results indicate that exposure has no obvious influence on the failure process and ultimate strains of specimens, but the compressive strengths of confined columns (fcc) increase with the increment of exposure time, especially for the partially confined concrete specimens. Moreover, due to the significant variation of unconfined concrete strength fco*), the retentions of fcc and fcc/fco * exhibit an opposite trend. Therefore, the increase of fco* should be considered when using the parameter of the confined-to-unconfined ratio of strength to evaluate the long-term performance of the specimens.


2022 ◽  
pp. 104047
Author(s):  
Eman Saleh ◽  
Ahmad Tarawneh ◽  
Hazim Dwairi ◽  
Mohammad AlHamaydeh

2021 ◽  
Author(s):  
Greg White ◽  
Mitch Sterling ◽  
Matt Duggan ◽  
Jordan Sterling

FAARFIELD is a common mechanistic-empirical software that uses a combination of layered elastic and finite element methods for the determination of rigid aircraft pavement thickness. The primary input parameters are the aircraft type, mass and departures, concrete flexural strength, sub-base material and thickness, as well as subgrade support characteristic. A parametric sensitivity analysis, including three common commercial aircraft and four subgrade conditions, determined that concrete thickness was most sensitive to concrete strength and aircraft mass. The concrete thickness was least sensitive to the sub-base material and thickness and was moderately sensitive to the subgrade condition and aircraft departures. These relative sensitivities were consistent when the results were analysed based on average percentage change in concrete thickness, the average slope of lines of best fit for normalised parameter values and the coefficients of a numeric linear regression for concrete thickness. It is recommended that designers focus their attention on accurately estimating realistic concrete strength and aircraft mass values, as these parameters had the greatest influence on concrete thickness.


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