Experimental study on recycled steel fiber concrete
Some basic properties of recycled steel fiber aggregate were tested, such as surface features, water absorption, apparent ensity, crushing index, cube compressive strength and so on. Recycled steel fiber aggregate were used to replace the natural aggregate by 0%, 25%, 50% and 100% proportion to make concrete. Afterward, compressive strength, splitting tensile strength and flexural strength were investigated at ages 3, 7 and 28 days. The results showed that thorn appearance of recycled steel fiber aggregate makes packing density decrease, crushing value and absorption increase. The compressive strength, splitting tensile strength and flexural strength of the recycled concrete depend on the mix proportions. Generally, the strength of recycled concrete can be 15–25% lower than that of concrete made with virgin aggregate.
Recycling and reuse of waste concrete in China: Part I. Material behaviour of recycled aggregate concrete
Abstract From the viewpoint of environmental preservation and effective utilization of resources, it is beneficial and necessary to reuse waste concrete as recycled concrete aggregate (RCA) for new concrete, often referred to as recycled aggregate concrete (RAC). In the recent years, intensive researches on this topic have been carried out in China and several successful applications of RAC in practical engineering were also performed. This paper provides an introduction of the background information for the recycling of waste concrete in China and a critical review of the related studies and achievements on the material behaviour of RAC. The following aspects are mainly focused on: the production of RCA, the mechanical behaviour of RAC (both strength and deformation characteristics) and the durability aspects of RAC. Furthermore, a brief introduction to the provisions for RCA and material behaviour of RAC specified in the first standard for RAC in China—Technical Code for Application of Recycled Aggregate Concrete (DG/TJ07-008), issued in 2007, was also presented.
Study on Compressive Strength of Recycled Aggregate Concrete
Experimental work for the compressive strength of recycled aggregate concrete was designed and performed with 264 cubes. The results indicated that the recycled coarse aggregate (RCA) replacement ratio has a remarkable influence on the compressive strength of recycled aggregate concrete,the relationships between the compressive strength and the m w/m c ratio are also different for different RCA replacement ratios and the developments for the compressive strength of recycled aggregate concrete are not exactly the same as that of normal concrete.Nevertheless, the compressive strength of recycled aggregate concrete can achieve the target compressive strength by adjusting the m w/m c ratio. Finally, based on the test results, the m w/m c ratio for achieving a target strength of 30 MPa for concrete with different RCA replacement ratios is presented.