Fresh, Mechanical, and Durability Characteristics of Self-Consolidating Concrete Incorporating Recycled Concrete Aggregate and Recycled Asphalt Pavement.

摘要

In this world, with any industry in general and construction industry in particular, it is quite difficult to manage Nature and Construction with harmony. This can be achieved or on the other hand, the nature can be saved from the noxious effects by means of using Eco-friendly materials in construction. The recent years saw tremendous construction and demolition phases, living an awful lot of waste are putting a huge pressure on the environment. This encourages the construction industry to put its hands on waste materials, which will help in life cycle of natural resources and also leads to sustainable development. In this study recycled concrete aggregate and recycled asphalt pavement (RCARAP) are used in the production of self-consolidating concrete (SCC) with varying percentage replacements of natural coarse aggregate (NCA). Using sustainable technologies such as supplementary cementitious materials (SCMs), combined with the recycled aggregates, is expected to enhance the concrete efficiency and performance. However, to qualify such mixtures to be used for the intended cause, detailed study should be carried out for mixtures to bring them into practice. A total of 16 concrete mixtures were prepared and tested. Mixtures were divided into four different groups, with constant water to cementitious material ratio of 0.4, based on the RCARAP content: 0, 25, 50, and 75% of coarse aggregate (CA) replaced by RCARAP. Design mixtures were used so as to get the slump flow higher than 500 mm (19.7 in). The control mixture for each group was prepared with 100% Portland cement while all other mixtures were designed with different combinations of Portland cement, fly ash and slag. For replacing fly ash and slag separately, 70% of cement was replaced with fly ash and slag, whereas for the combination of fly ash and slag, 50% of Portland cement was replaced by both the constituents (25% each). Fresh properties such as flow ability, deformability; filling capacity, and resistance to segregation of concrete at the time of casting, were investigated. Moreover, the compressive strength, tensile strength, permeability and the unrestrained shrinkage test were investigated. Partial replacement of the cement using Fly ash and Slag resulted in smaller 28-days-compressive strength as compared with the control mixes. The study further suggested that though the partial replacement of Fly ash and Slag had adverse effect of 28-days compressive strength, number of mixes have exceeded the minimum SCC requirements, even with 75% RCARAP. Finally, several mix designs from the study have met the minimum Illinois Department of Transportation (IDOT) compressive strength requirements for many engineering applications such as pavements and bridges. This gives an idea that in future the practical applications of results from the research are feasible.