Strength criterion of recycled aggregate concrete under triaxial Compression: Model calibration

In recent years, recycled aggregate concrete (RAC) has become a research hotspot in the field of urban construction because of its resource utilization of construction waste. However, compared with original concrete, its strength is still low, which requires additional nano-SiO2 (NS) and fiber. In order to study the mechanism of strength improvement of RAC, this paper takes NS and polyvinyl alcohol (PVA) fiber as variable parameters; uniaxial and triaxial compression tests were carried out on RAC with PVA fiber and NS, and the mechanical properties of RAC were investigated The result shows that within the range of 3% NS content, an increase in the NS substitution rate causes the mechanical properties of RAC to improve significantly. The compressive strength of RAC increases again after adding PVA fiber; through a SEM (scanning electron microscopy) analysis of the specimen, it was found that the NS filled the micro-pores and micro-cracks in the RAC, and the PVA fiber changed the contact range between recycled aggregate and mortar, so the microstructure of the material was more compact. The mechanism of RAC strength improvement is explained in the microcosmic view.

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Analysis of Stress - Strain Curve on Recycled Aggregate Concrete under Uniaxial and Conventional Triaxial Compression

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.168-170.900 ◽

2010 ◽

Vol 168-170 ◽

pp. 900-905 ◽

Cited By ~ 2

Author(s):

Hai Feng Yang ◽

Zhi Heng Deng ◽

Ying Huang

Keyword(s):

Lateral Pressure ◽

Triaxial Compression ◽

Strain Curve ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Peak Strain ◽

Stress Strain Curve ◽

Stress Strain ◽

Aggregate Concrete ◽

Confining Pressures

43 Φ50mm × 100mm column stress - strain curve tests are completed through RMT-201, which studied the compressive stress - strain curves of recycled aggregate concretes at distinct confining pressures under conventional triaxial stress state. This article, has analyzed the influence of different water-cement ratios, confining pressures on the curves, and raised constitutive equations of triaxial compression stress - strain curves for the different strength of recycled aggregate concretes.The brittleness indexes for recycled aggregate concrete under distinct confining pressures were analyzed contrastively. The result showed that: the failure modes of recycled aggregate concrete specimens are similar to those of ordinary concretes, but the final failure patterns of recycled aggregate and ordinary aggregate are quite different; with the increase of lateral pressure, the peak stress and peak strain of recycled aggregate concrete show linear growth; recycled aggregate concrete compressive stress - strain curves under the uniaxial and triaxial stress states are similar to ordinary aggregate concrete, yet peak strain shows signs of larger growth; with the increase of lateral pressure, the brittleness of recycled aggregate concrete reduces. The brittleness index of high-strength recycled aggregate concrete is larger wholly than that of ordinary recycled aggregate concrete and with confining pressure reaching a certain value, the brittleness index remains stable.

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