scholarly journals The Effect of Curing Conditions on Selected Properties of Recycled Aggregate Concrete

2020 ◽  
Vol 10 (13) ◽  
pp. 4441 ◽  
Author(s):  
Anna M. Grabiec ◽  
Daniel Zawal ◽  
Waheed Adewale Rasaq
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Water Evaporation ◽  
Concrete Aggregate ◽  
Slag Cement ◽  
Curing Conditions ◽  
Furnace Slag

The paper presents the influence of different curing conditions—wet, dry, and protection against water evaporation (PEV)—on selected properties of concretes with different amounts of recycled concrete aggregate (RCA) previously subjected to atmospheric CO2 sequestration. Two types of cement were used, Portland cement and blast-furnace slag cement. The study was performed in laboratory conditions (at the temperature of 20 ± 1 °C and relative humidity of about 60%), according to currently applicable test procedures for most of the measured characteristics of concrete. Additionally, the eco-efficiency indexes (bi and ci) as well as the eco-durability S-CO2 index were calculated. It was found that dry conditions cause the properties of concrete to deteriorate, especially concrete made of blast-furnace slag cement, while PEV allows the achievement of results comparable to wet conditions. Moreover, for series with the highest amounts of coarse recycled aggregate and after longer periods of curing, the difference between the effects of wet curing and protection against water evaporation disappears. The eco-efficiency and eco-durability indexes approach confirms the beneficial effect of blast-furnace slag cement used as a binder, but on the condition of using a proper way of curing.

scholarly journals The Effect of Curing Conditions on Selected Properties of Recycled Aggregate Concrete

2020 ◽  
Author(s):  
Anna M. Grabiec ◽  
Daniel Zawal ◽  
Waheed Adewale Rasaq
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Water Evaporation ◽  
Concrete Aggregate ◽  
Slag Cement ◽  
Curing Conditions ◽  
Furnace Slag

The paper presents the influence of different curing conditions – wet, dry and protection against water evaporation on selected properties of concretes with different amount of recycled concrete aggregate previously subjected to atmospheric CO2 sequestration. Additionally, the eco-efficiency bi and ci indexes as well as eco-durability S-CO2 index were calculated. It was found that dry conditions deteriorate the properties of concrete, especially made of blast furnace slag cement, while protection against evaporation allows to achieve results comparable to wet conditions. Moreover, for series with the highest amount of coarse recycled aggregate and after longer period of curing, the difference between the effects of wet curing and protection against water evaporation disappears. The eco-efficiency and eco-durability indexes approach confirms the beneficial effect of blast-furnace slag cement used as a binder but on condition of proper way of curing.

scholarly journals Effect of Mineral Admixtures on the Performance of Low-Quality Recycled Aggregate Concrete

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 596
Author(s):  
Yasuhiro Dosho
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mineral Admixtures ◽  
Structural Concrete ◽  
Aggregate Concrete ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

To improve the application of low-quality aggregates in structural concrete, this study investigated the effect of multi-purpose mineral admixtures, such as fly ash and ground granulated blast-furnace slag, on the performance of concrete. Accordingly, the primary performance of low-quality recycled aggregate concrete could be improved by varying the replacement ratio of the recycled aggregate and using appropriate mineral admixtures such as fly ash and ground granulated blast-furnace slag. The results show the potential for the use of low-quality aggregate in structural concrete.

scholarly journals Properties of Concrete Using Treated Low-Class Recycled Coarse Aggregate and Blast Furnace Slag Sand

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 843
Author(s):  
Yuji Miyazaki ◽  
Takeshi Watanabe ◽  
Yuji Yamada ◽  
Chikanori Hashimoto
Keyword(s):  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Coarse Aggregate ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Hardened Concrete ◽  
Freezing And Thawing ◽  
Aggregate Concrete ◽  
Recycled Coarse Aggregate ◽  
Furnace Slag

Since high quality natural aggregates are becoming scarce, it is important that industrial recycled products and by-products are used as aggregates for concrete. In Japan, the use of recycled aggregate (RG) is encouraged. Since, strength and durability of recycled aggregate concrete is lower than that of normal aggregate concrete, the use of recycled aggregate has not been significant. In order to improve physical properties of concrete using recycled coarse aggregate, blast furnace slag sand has been proposed. Recently, blast furnace slag sand is expected to improve durability, freezing, and thawing damage of concrete in Japan. Properties of fresh and hardened concrete bleeding, compressive strength, and resistance to freezing and thawing which are caused by the rapid freezing and thawing test using liquid nitrogen is a high loader than the JIS A 1148 A method that were investigated. As a result, concrete using treated low-class recycled coarse aggregate and 50% or 30% replacement of crushed sand with blast furnace slag sand showed the best results, in terms of bleeding, resistance to freezing and thawing.

Mechanical Properties of Concrete Using Treated Recycled Concrete Aggregate in Marine Environment

2020 ◽  
Vol 841 ◽  
pp. 138-143
Author(s):  
Sallehan Ismail ◽  
Mahyuddin Ramli
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Marine Environment ◽  
Impact Resistance ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Recycled Concrete Aggregate ◽  
Curing Conditions

This study also investigates the effectiveness of multiple surface modification of recycled concrete aggregate (RCA) with respect to mechanical properties of the resultant recycled aggregate concrete (RAC) when exposed to various curing conditions, namely, normal water (Nw) and seawater (Sw). The properties included compressive and flexural strength and impact resistance. Findings show that effect inclusion of the treated coarse RCA is significant in enhancing the mechanical properties of RAC. The exposure to Sw appears to affect the degradation of the compressive strength of RAC remarkably in a marine environment. In this case, however, using of treated RCA is found beneficial in decreasing the deterioration in the compressive strength of RAC.

Compressive Strength Tests of Recycled Green Concrete Containing Ground Granulated Blast-Furnace Slag

2014 ◽  
Vol 496-500 ◽  
pp. 2486-2490 ◽  
Author(s):  
Jia Guo Sun ◽  
Yan Ling Gu
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Blast Furnace Slag ◽  
Coarse Aggregate ◽  
Physical And Mechanical Properties ◽  
Recycled Concrete ◽  
Recycled Aggregate ◽  
Green Concrete ◽  
Recycled Coarse Aggregate ◽  
Furnace Slag

This study used waste concrete as a recycled coarse aggregate and added an appropriate proportion of groundgranulated blast-furnace slag (GGBFS) to formulate recycled concrete. Based on the recycled coarse aggregate and GGBFS content, 24different mixture ratios were formulated, and then an experimental study of the slumpand compressive strength of the mixtures was conducted. The results showed that because slag can improve the physical and mechanical properties and performances of ordinary concreteand can compensate for certain natural deficiencies occurring in recycled coarse aggregate,GGBFS and recycled coarse aggregate can form recycled aggregate green concrete with a slump of 170mm and a 28-day compressive strengthof 50MPa.

Use of Coarse Recycled Concrete Aggregate in Ternary Blended Portland Cement Concrete

2020 ◽  
Vol 2674 (10) ◽  
pp. 705-714
Author(s):  
Seth Wagner ◽  
Gabrielle Wickizer ◽  
Douglas Cleary ◽  
Gilson R. Lomboy ◽  
Danielle Kennedy ◽  
...  
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Mechanical Performance ◽  
Recycled Concrete ◽  
Recycled Aggregates ◽  
Concrete Aggregate ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates ◽  
Furnace Slag

The purposes of this study were to (a) investigate concrete pavement mixtures with recycled concrete aggregates using ternary blended cementitious binders, (b) measure the fresh and hardened properties of the concrete mixtures, and (c) assess the durability of concrete implementing the use of recycled coarse aggregates with ternary binders. Mixtures had recycled concrete aggregates at varying replacement rates. The binders were combinations of Portland cement, Class C and F fly ashes, and ground granulated blast furnace slag. At 50% replacement of virgin aggregates, some specimens showed comparable mechanical performance to the control mix. Performance is heavily tied to quality of recycled aggregates. The combined use of fly ash and blast furnace slag showed improvements in results for drying shrinkage, freeze–thaw durability, resistivity, and alkali–silica reaction mitigation.

scholarly journals Pore Structure and Influence of Recycled Aggregate Concrete on Drying Shrinkage

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yuanchen Guo ◽  
Jueshi Qian ◽  
Xue Wang
Keyword(s):  
Fractal Dimension ◽  
Pore Structure ◽  
Drying Shrinkage ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Water Evaporation ◽  
Concrete Aggregate ◽  
Aggregate Concrete ◽  
Mercury Intrusion

Pore structure plays an important role in the drying shrinkage of recycled aggregate concrete (RAC). High-precision mercury intrusion and water evaporation were utilized to study the pore structure of RAC, which has a different replacement rate of recycled concrete aggregate (RCA), and to analyze its influence on drying shrinkage. Finally, a fractal-dimension calculation model was established based on the principles of mercury intrusion and fractal-geometry theory. Calculations were performed to study the pore-structure fractal dimension of RAC. Results show the following. (1) With the increase in RCA content, the drying shrinkage values increase gradually. (2) Pores with the greatest impact on concrete shrinkage are those whose sizes ranging from 2.5 nm to 50 nm and from 50 nm to 100 nm. In the above two ranges, the proportions of RAC are greater than those of RC0 (natural aggregate concrete, NAC), which is the main reason the shrinkage values of RAC are greater than those of NAC. (3) The pore structure of RAC has good fractal feature, and the addition of RCA increases the complexity of the pore surface of concrete.

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