Mechanical performance and environmental impacts of self-compacting concrete with recycled demolished concrete blocks

2021 ◽  
Vol 293 ◽  
pp. 126129
Author(s):  
Jing Li ◽  
Jun Zhang ◽  
Shuna Ni ◽  
Libo Liu ◽  
Lubinda F. Walubita
Author(s):  
Youcef Ghernouti ◽  
Bahia Rabehi ◽  
Sabria Malika Mansour

In this paper, influence of heat treatment on evolution of mechanical strengths at early age, less than 24hours of self-compacting concretes containing limestone powder and silica fume as fine materials was investigated experimentally. Two compositions of self-compacting concrete have been studied; the first is elaborated with silica fume addition and the second with limestone powder, each mixture were prepared with a constant water/binder ratio of 0.39. Concrete samples were either cured in water at (23±1°C), or steam cured at 65°C maximum temperature over six hours (6h) curing period. Tests of mechanical strengths were performed on specimens cooled down slowly to room temperature after heating.The obtained results show that all self-compacting mixtures exhibited satisfying fresh properties and check EFNARC specifications of self-compacting concrete (slump flow diameter higher than 650mm, L-box ratio higher than 80% and sieve stability less than 17%).Mechanical strengths of concrete containing limestone addition are slightly lower than those of concrete based on silica fume at all ages. Moreover, heat treatment generates an improvement of compressive and flexural strength. Interesting compressive strengths are obtained. At 24 hours, after heat treatment, the strengths are already greater than 35 MPa. The values ​​are 37 MPa and 40 MPa for self-compacting concrete containing limestone powder and silica fume respectively compared to 40 MPa and 46 MPa obtained at 7 days for the corresponding non-heat treated concretes. Compressive strength gain of SCCs mixtures with limestone powder and with silica fume, undergoing heat treatment at the age of 24hours is 85% and 75% respectively compared to SCCs mixtures cured in water.


2021 ◽  
Vol 894 ◽  
pp. 95-101
Author(s):  
Sepehr Ghafari ◽  
Fereidoon Moghadas Nejad ◽  
Ofelia Corbu

In this research, a sustainable approach is followed to develop efficient mixtures incorporating recycled fine aggregate (RFA) remained from structure demolition as well as limestone filler (LF) from production of hot mix asphalt (HMA). The LF is a byproduct of the drying process in HMA production plant which is not entirely consumed in the production of the HMA and must be hauled and disposed in landfills. The maximum particle size of the LF is approximately 40 µm. Self-Compacting Concrete (SCC) mixtures were designed replacing 5% and 10% of the cement with LF. Incorporation of 50%, and 100% RFA with the fines in the mixtures were considered with and without addition of the LF. Due to the formwork and prefabrication restrictions, the paste volume and the high range water reducer content were tuned in such a way that the slump flow of the mixtures remained between 660 mm to 700 mm without segregation. Durability and mechanical performance of the mixtures were evaluated by resistance against freeze-thaw scaling exposed to deicing agents and compressive strength. It was observed that the SCC mixtures containing 10% LF outperformed those without the use of LF while 5% SCC mixtures did not exhibit tangible superiority. Incorporation of RFA as the fine fraction degraded the durability of all the mixtures. While replacing all the fine fraction with RFA significantly impaired durability and compressive strength, 50% RF mixtures could be designed containing 10% LF that remained in the allowable limits.


2011 ◽  
Vol 306-307 ◽  
pp. 1084-1087 ◽  
Author(s):  
Jing Li ◽  
Xian Feng Qu ◽  
Lin Fu Wang ◽  
Chong Qing Zhu ◽  
Juan Li

In order to study cubic compressive strength of recycled coarse aggregates-filled concrete systematically, recycled coarse aggregates with the particle size from 50 to150mm are made from waste solid contents, which are artificially broken from abandoned rubble and concrete blocks. Based on the mix proportion design method of ordinary concrete and test code for hydraulic concrete, 3 groups of recycled coarse aggregates-filled concrete cubic specimens were prepared and the compressive strength of the specimens were tested. The results showed that basic failure pattern of recycled coarse aggregates-filled concrete are longitudinal splitting failure, and that cubic compressive strength is higher than that of self-compacting concrete.


2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Chengzhi Wang ◽  
Xin Liu ◽  
Wei Liu ◽  
Zhiming Li

In the water resources allocation project in Pearl River Delta, in order to optimize the structural design, the deep buried tunnel adopts the composite lining structure. However, the weakest link in a complex structure is the connection between two different interfaces. This paper reports the findings of an experimental study that was undertaken to investigate the interface mechanical performance of steel self-compacting concrete composite structure subjected to cyclic loads. In this study, different shear connectors are considered, and six different specimens were designed and tested, respectively. The test is used to research the effect of the different shear connectors on the bearing capacity and interface mechanical properties of composite structure in an experimental study. According to these test results, a detailed analysis was carried out on the relationships, such as the stress-strain and load-displacement relationships for the specimen. These tests show that the shear connectors will significantly enhance the bearing capacity and interface mechanical properties of the composite structure. Among them, the comprehensive performance of the specimens using the stud-longitudinal ribs shear connectors is the best. Additionally, a finite element analysis (FEA) model was developed. The comparison of the simulation results with the experimental results shows that this FEA is applicable for this type of experiment.


2016 ◽  
Vol 78 (11) ◽  
Author(s):  
Juli Asni Lamide ◽  
Roslli Noor Mohamed ◽  
Ahmad Baharuddin Abd Rahman

This paper presents an experimental test program that was carried out to investigate the shear performance of steel fibre self-compacting concrete (SFSCC) beams. In this paper, the mechanical performance of results from all mixtures used to cast normal concrete (NC), self-compacting concrete (SCC) and steel fibre self-compacting concrete (SFSCC) were also investigated. In total, 27 cubes, 9 cylinders, 9 prisms and 9 beams were prepared for the assessment of mechanical properties of three different mixtures. Four beams (125 mm x 250 mm x 2200 mm) were tested and cast using three different concrete mixtures, having two different spacing of stirrups as a result of 50% reduction of the stirrups amount. Three beams with different mixtures having similar stirrups spacing 125mm while the fourth beam with SFSCC mixes having 250mm stirrups spacing. The results show that the mechanical properties were positively affected with steel fibres inclusion. The addition of steel fibres showed an increment up to 40% in the shear load capacity for B-SFSCC125 compared to B-NC125 and B-SCC125.  In addition, the crack pattern of B-SFSCC was found better than B-NC and B-SCC.   


2014 ◽  
Vol 51 ◽  
pp. 179-186 ◽  
Author(s):  
Alireza Khaloo ◽  
Elias Molaei Raisi ◽  
Payam Hosseini ◽  
Hamidreza Tahsiri

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