Papers by Keyword: Waste Concrete

Abstract: This investigation is focused on possibility of partial cement replacement in concrete mixture and its environmental assessment. The cement in concrete mixture is replaced by recycled cement powder from modified construction and demolition (C&D) waste. Recycled cement powder were prepared in laboratory from C&D waste of high quality road concrete. The main goal of this investigation is optimize amount of recycled cement powder used as partial replacement of cement in concrete mixture according to mechanical, deformation and physical properties of concrete and environmental impact. The properties of the fine-aggregate concrete with partial replacement of cement by recycled cement powder were tested for this verification. The life cycle analysis was calculated for this optimization. The properties and environmental assessment of the fine-aggregate concrete with partial replacement of fine aggregate by fine recycled aggregate were examined for comparison.

Abstract: The recycled cement production, utilizing all components of the waste concrete without separation treatment as raw materials, provides an effective method for the high value-added resource recovery of waste concrete. However, as fine aggregate (sand) is the main siliceous component in the recycled cement raw materials prepared from waste concrete, its excessive high-crystalline silica content negatively impacts the burnability of raw meal and the property of clinker. By comparing and analyzing the results of burnability test, XRD patterns of clinker and compression strengths of cement paste, this paper attempts to explore the effect of F-S mineralizer on the calcination of recycled cement clinker produced from waste concrete. It could be concluded that F-S mineralizer has a significant improvement on the burnability of recycled cement raw meal, and the f-CaO content decreases with the mineralizer dosage rising. Moreover, in the case of calcination temperature at 1350°C, F-S mineralizer contributes to the enhancement of compression strength of recycled cement paste. Early high-strength minerals ( and C₁₁A₇⋅CaF₂) are prime motivator to early strength increment, while long-term strength benefits from mineralizer’s improving on hydration activity of silicate mineral in clinker.

Abstract: Utilizing construction waste, mainly waste concrete, to produce recycled cement, provides possibility for realizing the closed circulation between concrete and cement, which is an effective way for sustainable development of cement and concrete industry. Waste clay brick (WCB) and its surface-coated waste mortar are inevitably introduced into the raw meals while waste concrete is used in cement production. So on the basis of the composition characteristics of construction waste, considering of optimizing the performance of recycled cement and improving the adaptability of recycled cement to complex raw material, it's necessary to study the effect of raw meal mixing waste concrete and WCB on sintering process and property of recycled cement clinker. Mixing waste concrete and WCB in three different proportions, the burnability of raw meal, clinker mineral composition, clinker mineral morphology and hydration characteristics of recycled cement have been studied in this paper. The results indicate, the presence of WCB is beneficial for the generation and development of silicate minerals; with increasing proportion of WCB, the content of f-CaO in recycled cement clinker rises, the structure of C-S-H gel from hydration product presents higher densification and the compression strength of 3d and 28d curing period are enhanced.

Abstract: This paper test the strength intensity,water absorption property of 10 baking—free bricks using the matrix cementing component in waster concrete as the material,studies the effect of m~ing ratio and maintenance time on pmpe~y to get the best mKing ratio of this kind of brick.It also analyzes the intension resources of this brick.

Abstract: As an eco-material, the application of recycled aggregate concrete and rapid repair concrete has been deeply researched in recent years. But the application of recycled aggregate concrete with recycled fine aggregate and recycled powder in pavement rapid repair project is seldom. Combing with the related literatures and our own engineering practice, the state-of-the-art report of recycled aggregate concrete and rapid repair concrete is presented, and hope to supply a new way to solve the long-standing issue of waste cement concrete recycling and rapid opening traffic simultaneously.

Abstract: In the process of urban development, with the reconstruction of old city, a lot of waste concrete will be generated. At the same time, civil engineering construction, earthquakes and wars also can generate a large number of waste concrete. The existence of waste concrete will directly pollute environment and occupy the land resources. The recycling utilization of waste concrete is benefit to environmental protection and saving resources, and is also benefit to realize the sustainable development of building materials. Waste concrete research situations in China and abroad were introduced. The crushing and regeneration technology of waste concrete were studied. The material properties of recycled concrete were analyzed and some advices about development of recycled concrete in China were presented.

Abstract: In modern society, the development of urbanization process makes the increasing waste concrete and natural aggregate resource increasingly drying up. Recycled concrete research has become the inevitable development of society. This paper briefly introduces the research status of waste concrete recycling, and points out the current waste engineering application research status and existing problems of the concrete utilization. The industrialization of recycled concrete is in accordance with the needs of environmental protection and sustainable development strategy.

Abstract: The performance of recycled coarse aggregate has significant effects on recycled concrete. The performance of recycled coarse aggregate were tested according to Recycled coarse aggregate for concrete (GB/T 25177-2010). The Result showed that the recycled coarse aggregate grading in accordance with regulation requirements, and compared with the natural coarse aggregate: high powder content and water absorption, low needle and plate particle content, low apparent density, compression capability as low as soundness. And the property of recycled coarse aggregate after cleaning has the performance of guaranteeing the quality by using. Through the test results and consult the national regulation, the recycled coarse aggregate in Xinjiang can be preliminary division to the categories of I and II.

Abstract: this paper analyses the reutilization of waste concrete is feasible in technology, technical index, and its concrete recycling huge economic, environmental benefits.

Abstract: Waste concrete as the main object of the study, was proved to be capable of producing recycled-cement. The chemical composition of recycled-cement was analyzed by X-ray diffraction and compared with industrial clinker from Onoda Company. The result of comparison showed that the minerals in recycled-cement were almost the same as the industrial clinker, except a little MgO and CA. The amount of four main minerals in cement clinker was reasonable. The mechanical property of mortar produced with recycled-cement was measured. The results showed that the compressive strength of recycled-cement mortar can reach the standard of mortar with P.O 32.5. The excess MgO and the strength grade of waste concrete we used in the research were identified as the restriction of the strength development of recycled-cement.