Papers by Keyword: Concrete Waste

Abstract: River sand, one of the ingredients for concrete when harvested uncontrollably from the river would cause destruction to the river environment. At the same time, the increasing concrete waste disposed at dumpsite after generated from construction and demolition activity causes environmental pollution. The approach of recycling concrete waste for use as a mixing component in concrete production would lessen the heavy reliance on natural sand supplies and lower the amount of concrete waste disposed. The current study investigates the effect of recycled fine aggregate obtained from concrete waste as sand replacement on concrete's workability, compressive strength, and water absorption. Five mixtures were made using varying amounts of recycled fine aggregate (0, 10, 20, 30 and 40% by weight of sand). All specimens were subjected to water curing. Three types test were conducted namely slump test, compressive strength test and water absorption test. Findings show that the integration of recycled fine aggregate up to 20% produces concrete with the targeted strength of 40MPa. Furthermore, the water absorption of the mixes is less than 3%, allowing it to be classified as good quality. Success in blending recycled fine aggregate in concrete production would contribute to saving river sand consumption and lesser concrete waste for a cleaner environment.

Abstract: Owing to the inability of waste concrete to be recycled, unlike aluminium or glass, it is one of the most harmful substances to the environment. Thus, most of the waste concrete was poured in every available space, resulting in environmental contamination due to the chemical content of the waste concrete. This involves the fabrication and characterization of cement bricks’ compressive strength made from concrete sludge waste in order to investigate the feasibility of re using waste concrete. The concrete waste was to substitute the cement composition within the bricks. The composition of cement and waste concrete is varied to investigate effect of its compressive strength and its microstructure. In general, the optimal formulation is 100 wt % cement and 0 wt % waste, with a compressive strength of up to 12 MPa on average. Increasing the waste composition by 50% reduces the compressive strength of the concrete bricks to 2MPa which limiting the range of application suitable with its properties.

Abstract: Recently, the construction industry uses the Recycled Concrete Aggregates (RCA)resulting from construction and demolition waste (CDW) to achieve sustainable requirements andeconomic benefits. In this paper, asphalt paving mixes were prepared with RCA instead of naturalaggregates for the base course in flexible road pavements and walking areas used by pedestrians andcyclists. Different asphalt mixes samples were prepared with different asphalt contents to meet therequired specifications. Additionally, several laboratory tests were carried out to assess mixturebehavior including the Marshall test. The results indicated that the mixture made with aggregates ofCDW have met all the requirements of Iraqi specifications of roads and bridges (SORB/R9). Thisinvestigation could be a useful guide for road engineers in designing asphalt mixtures from RCA.

Abstract: Materials play a fundamental role in any branch of civil engineering. From ancient times to the present day, society has required enormous amounts of construction materials, which implies an excessive exploitation of materials that come directly from nature. This paper explains the main differences, similarities, benefits and characteristics of the 2 designs of asphalt mixtures by means Marshall methodology. The first design is for control mixture, which was elaborated with a conventional asphalt AC-20 and 100% of natural aggregate (NA). The second design is for asphalt mixture with 30% of recycled concrete aggregate (RCA) and 70% of NA. Finally, it was determined that both designs have similar characteristics, which indicates that the use of 30% RCA in asphalt mixtures is adequate. In addition, it represents economic and environmental savings.

Abstract: The highway pavement quality and lifetime depend on its different layers such as subgrade, sub-base and base courses. It is of great importance for subgrade soil layer to have the excellent properties as it is the one to lower or increase the project cost. This paper discusses the utilization of lime and fines from concrete waste to enhance the strength of silty sand soil. California Bearing Ratio (CBR) and shear strength were evaluated. The content such as 0%, 2%, 4%, 6%, 8% and 10% were used. The CBR and shear strength of soil increased with the increase of lime or concrete content. The optimum lime and concrete content which maximized CBR were 6% and 8% respectively. The shear strength improvement was also noticed. No optimum content from both stabilizers which gave maximum shear strength.

Abstract: We live in an era where people should be more aware of pollution and its consequences. The present paper reveals a way protecting the environment while producing high quality concrete. What make this type of concrete environmentally friendly are the recycled aggregates in the concrete composition amongst with eliminating the ecological impact by saving large amounts of natural aggregates resources. Recycling concrete comes with many other advantages that lead to waste reduction, economy in waste transportation and storage taxes, which are becoming increasingly expensive. This research is based on mix design and experimental tests carried out on C20/25 strength class concrete with uncontaminated leftover concrete aggregates (LCAgg). It reveals favorable results in order to militate for recycled concrete aggregate uses in regular concrete strength classes respectively for common structural elements, mainly for slabs. River sand (0/4 mm) and coarse aggregates (4/8 mm and 8/16 mm): natural sources or recycled concrete type-alternatively used in several mixes-were utilized in concrete mixes.

Abstract: The quality of RCA is influenced by the processing method and quality of original concrete. The general character of RCA, RCA and TR A 0006-2000(concrete using recycled aggregate) are introduced. The execution of RAC work, examples of real constructions with RAC, recycling of concrete powder originated from production of RAC and barriers of using RAC are discussed.