scholarly journals A comparative analysis of elasticity modulus of recycled aggregate concrete with silica fume

2018 ◽  
Vol 24 (6) ◽  
pp. 1069-1078
Author(s):  
Özgür Çakır ◽  
Hasan Dilbas
Keyword(s):  
Comparative Analysis ◽  
Silica Fume ◽  
Elasticity Modulus ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Aggregate Concrete

scholarly journals Combined effects of nano-silica and silica fume on the mechanical behavior of recycled aggregate concrete

2021 ◽  
Vol 10 (1) ◽  
pp. 819-838
Author(s):  
Tang Yunchao ◽  
Chen Zheng ◽  
Feng Wanhui ◽  
Nong Yumei ◽  
Li Cong ◽  
...  
Keyword(s):  
Silica Fume ◽  
Structural Engineering ◽  
Tensile Tests ◽  
Cementitious Materials ◽  
Recycled Aggregate Concrete ◽  
Supplementary Cementitious Materials ◽  
Recycled Aggregate ◽  
Hydration Reaction ◽  
Nano Silica ◽  
Aggregate Concrete

Abstract Recycled aggregate concrete (RAC) is an environmentally friendly material. However, owing to inherent characteristics of the recycled aggregate (RA), it is difficult to promote and apply it in structural engineering. Silica fume (SF) and nano-silica (NS) have different characteristics as additives for RAC. It has been proven that adding SF only enhances the strength of RAC at a later stage, and NS can improve the early strength of RAC owing to its high pozzolanic activity. In this study, to further improve the properties of RAC, two types of additives were combined into RAC, which was named SF-NS-modified RAC (SSRAC). Compression and split tensile tests were conducted to analyze the mechanical properties of SSRAC at different curing ages. The results indicated that the combined addition of NS and SF improved the performance of RAC at early and later curing ages. Scanning electron microscopy and X-ray diffraction analyses were performed to explore the NS and SF mechanism. The results indicated that SF and NS in SSRAC had a good pozzolanic effect and underwent a secondary hydration reaction with calcium hydroxide to increase the production of calcium silicate hydrate, resulting in an increase in the properties of the interface transition zone. Finally, 6% SF and 2 or 3% NS are recommended as supplementary cementitious materials for RAC.

The Influence of Mineral Admixtures on the Wear-Resisting Property of Recycled Aggregate Concrete

2013 ◽  
Vol 639-640 ◽  
pp. 417-422
Author(s):  
Wei Dong Chen ◽  
Jian Yin ◽  
Wei Min Song ◽  
Yi Chi
Keyword(s):  
Fly Ash ◽  
Flexural Strength ◽  
Silica Fume ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mineral Admixtures ◽  
Aggregate Concrete

It was tested the strength and wear value of recycled aggregate concrete mixing fly ash, slag, silica fume and double-mixture or three-mixture in deferent age. The results show that the wear value of recycled aggregate concrete mixing 30% fly ash is more than reference concrete at 3days, but can improve final wear-resisting property significantly. The wear value of recycled aggregate concrete mixing 30% double-mixture of fly ash and silica fume is much lower than reference concrete at 3days, and improve early wear-resisting property significantly. The flexural strength of the concrete is 4.26MPa at 3days, which can satisfy the traffic requirement. The wear value of recycled aggregate concrete mixing 30% three-mixture of fly ash, slag and silica fume is lower than reference concrete at 3days, but the declining rate is not significant. It investigates mechanics of double-mixture technique which improves wear-resisting property at the same time.

scholarly journals Evaluating the durability of recycled concrete made of coarse recycled aggregate concrete containing silica-fume and natural zeolite

2020 ◽  
Vol 19 (3) ◽  
pp. 457-473
Author(s):  
Hasan Jalilifar ◽  
◽  
Fathollah Sajedi ◽  
Vahid Razavi Toosi ◽  
◽  
...  
Keyword(s):  
Water Absorption ◽  
Silica Fume ◽  
Natural Zeolite ◽  
Full Scale ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Conventional Concrete ◽  
Aggregate Concrete ◽  
Four Levels

This experimental study evaluates the durability of recycled aggregate concrete (RAC) containing silica-fume (SF) and natural zeolite (NZ). For this purpose, four levels of recycled coarse concrete aggregates (RCA) were replaced with natural coarse aggregates (NCA). To compare the effect of pozzolans, three levels of SF (5%, 10%, and 15%) and three levels of NZ (10%, 20%, and 30%) were replaced with cement. To evaluate the durability of RAC, 28 mixed designs were made and the following were measured: compressive strength (CS), water absorption by immersion (WA by immersion), water absorption by capillary (WA by capillary), electrical resistance (ER), electrical conductivity (EC) and rapid chloride penetration test (RCPT). The results indicated that WA by immersion and WA by capillary of RAC increased with enhanced RCA incorporation. On the other hand, the pozzolanic reaction of 10% of SF and 10% of NZ decreased capillary pores and structural weakness of full-scale RAC. However, due to the internal chemical changes of RAC, contrary to the WA by immersion and WA by capillary, compared to conventional concrete (CC), a lower EC and unchanged ER values of RC100 containing pozzolans were seen. The scanning electron microscopy (SEM) revealed that compared to NZ, a 10% of SF significantly improved the microstructure of full scale RAC.

scholarly journals Water-glass Module on Mechanical Properties of Geopolymer Recycled Aggregate Concrete

2022 ◽  
Vol 2148 (1) ◽  
pp. 012060
Author(s):  
Zhaoyang Ding ◽  
Qun Su ◽  
Hongguan Bian ◽  
Qing Wang ◽  
Jinghai Zhou
Keyword(s):  
Mechanical Properties ◽  
Water Glass ◽  
Elasticity Modulus ◽  
Peak Stress ◽  
Hydration Product ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
National Standard ◽  
Peak Strain ◽  
Aggregate Concrete

Abstract Geopolymer recycled aggregate concrete (GRAC) was prepared by replacing cement with geopolymer and natural aggregate with wast concrete. The effect of water-glass modules on mechanical properties of GRAC was studied. It was found that there are tow kind of binding structures in geopolymer hydration product: C-A-S-H and N-A-S-H, they both contribute to the strength of GRAC. The value of size conversion coefficient of current national standard is inapplicable for GRAC, the calculation method of which is given in this paper. Elasticity modulus and peak stress of GRAC is proportional to water-glass modulus, and peak strain is inversely proportional and its constitutive equation was established.

Experimental Study on the Chloride Diffusivity of Recycled Aggregate Concrete

2010 ◽  
Vol 168-170 ◽  
pp. 1404-1408
Author(s):  
He Ying Qin ◽  
Yan Lin Zhao ◽  
Bo Guang Luo ◽  
Yi Hu Chen
Keyword(s):  
Diffusion Coefficient ◽  
Fly Ash ◽  
Silica Fume ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Chloride Diffusion ◽  
Partial Replacement ◽  
Chloride Diffusion Coefficient ◽  
Aggregate Concrete ◽  
Chloride Diffusivity

The study presented herein has been carried out in order to investigate the chloride diffusivity of recycled aggregate concrete (RAC). Meanwhile, the effect of the binder type, involving cement replacement materials such as, fly ash, slag and silica fume on the chloride diffusivity has also been investigated. For this purpose, RAC and concrete containing the different type of binders with w/b ratios of 0.35, 0.40, 0.45, 0.50, 0.55, and 0.60 were used. As a result, the chloride diffusion coefficient of RAC is higher than that of natural concrete and the partial replacement of cement with fly ash, slag and silica fume is effective in decrease in the chloride diffusion coefficient, measured by a rapid chloride conductivity test.

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