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Aggregates for Concrete

mately 60 to 75% of the volume of concrete. Aggregate properties significantly affect the workability of plastic concrete and also the durability, strength, thermal properties, and density of hardened concrete. This Bulletin describes types of aggregates normally used in …


aggregate has no significant effect on mixture proportions or workability when compared with control mixtures made with conventional aggregates. Although there are limitations to using recycled fine aggregates, these drawbacks can be generally overcome by …


Properties of aggregate and comparison of recycled aggregate concrete against natural aggregate concrete is performed according to requirements as such for its workability, compressive strength ...


The use of recycled aggregates (RA) for concrete production usually involves a reduction of the workability as measured by slump. This reduction is mainly due to higher absorption rates, rough-textured surfaces and particles with quite irregular shape from RA. Besides that, the slump test is a static test, whose result is influenced by its own weight and by internal friction between …


One study found that in order to produce similar workability as VA concrete 5% more mixing water was required when using just the coarse fraction of recycled concrete aggregates (coarse RCA) and up to 15% more mixing water when using both the coarse and fine fractions of RCA8-11. Issues of


This paper presents the results on workability testing as well as strength testing of self-compacting concrete containing partial/full coarse recycled concrete aggregates and ternary blended cement using ultrafine recycled powder (RP) and silica fume (SF).


Recycled concrete will have a higher absorption and lower specific gravity than conventional aggregates. To produce good quality, durable concrete containing a portion of recycled concrete aggregate often requires trial concrete mixes and close monitoring of the properties of the old recycled concrete, with mix adjustments made, as needed.


In practice it is difficult to separate recycled aggregates made of concrete of varying strengths in a reliable manner for re-use. In order to examine the properties of fresh and hardened concrete, tests were conducted on two concrete compositions. Recycled aggregates made of mature concrete of two compressive strengths, B = 20 and 55 N/mm2, as well as recycled aggregates …


This study presents the effects of recycled concrete aggregate (RCA) on the key fresh and hardened properties of concrete. RCA was used to produce high-workability concrete substituting 0- natural coarse aggregate (NCA) by weight. The slump and


recycled concrete as aggregate in new Portland cement concrete pavements. The dwindling supplies of high-quality natural aggregate, increasingly limited landfill space, swelling disposal costs, emphasis on the conservation of natural resources, and reduced construction costs are important reasons to consider the using recycled concrete ...


The recycled concrete aggregates have a significant water absorption capacity in a concrete mix. The simple volume replacement of NA by RA affects concrete workability and performance. For the mixing period of 10 minutes suggested by Evangelista and de Brito it was ...


Recycled concrete, or recycled aggregate concrete, is the concrete generated by mixing a certain proportion of cement and sand with waste concrete after being mechanically crushed, cleaned and screened. The workability of the concrete is determined by the rheological property of the mixture; the fluidity and workability of the fresh cement


The improvement in the workability of concrete mixtures can be ascribed to steric hindrance and ball-bearing effects from well dispersed O/W emulsion. The enhancement in the compressive strength can be attributed to the filler effect of the well-dispersed microscale particles of UEO. ... Utilizing recycled aggregate concrete in sustainable ...


Concrete (FRHSC) which use recycled aggregates that have originated from demolished construction wastes.The workability of FRHSC was measured in terms of compaction factor and V-B time in fresh state of concrete.


Recycling of concrete is a simple process. It involves breaking, removing, and crushing existing concrete into a material with a specified size and quality. As per study about 75 to 80% of total construction material consist coarse aggregate portion. When the structure is demolished, the waste concrete in a large quantity is produced.


Recycling of construction and demolition waste is a central point of discussion throughout the world. The application of recycled concrete as partial replacement of mineral aggregates in concrete mixes is one of the alternatives in the reduction of pollution and savings in carbon emissions. The combined influence of the recycled crushed concrete, lime, and natural pozzolana on the mechanical ...


However, the bulk density of IOT as aggregate is too large, which seriously affects the concrete properties. Therefore, in this paper, the effect of hydroxypropyl methylcellulose (HPMC) on the workability, mechanical properties, and durability of concrete …


The basic engineering properties of Recycled Concrete Aggregate (RCA) is evaluated and it is compared with the Normal Aggregate (NA). Similarly, the basic concrete properties like, compressive strength, workability etc. are studied for the different combinations of RCA with NA.


The recycled concrete waste aggregate (RCWA) was tested for grading, specific gravity, percent absorption and impact and crushing (% crushed). For the fresh concrete mix, slump and compaction factor test were carried out. Concrete samples are wet cured and tested at 7 and 28 days for compressive strength. Results show that the workability of ...


workability of the concrete using recycled aggregate. 2. Evaluation of Recycled Aggregate Properties Recycled aggregate can be generated from demolished construction structure which comprises of broken members or components likes the slab, beam, brick wall and others. Since the quality data of these broken materials are often


This study examines the workability, strength, and microstructure of high strength eco-concrete incorporating recycled clay brick aggregate and calcined clay. The study adopted a design mixes proportioning of 1:1:2 by weight at a constant water/binder ratio of 0.25.


showed that the workability of recycled aggregate is lower than the workability of natural aggregate concrete,the slump test was about 1.0cm slump for 60 % coarse recycled aggregate concrete and increases as the percent of recycled aggregate decreases . The compressive strength of recycled aggregate concrete with 60 % recycled aggregate, is


The use of recycled concrete aggregates as an alternative aggregate material in concrete has been studied over the past two decades. It is now recognized that the recycled aggregate concrete (RAC), where natural aggregates are replaced with recycled concrete aggregates, is a promising technology for conserving natural resources and reducing the environmental impact of concrete.


Keywords: hardened properties, natural coarse aggregate, recycled concrete aggregate, workability. 1. Introduction. Construction developments are on its peak in the 21 st century around the globe. There are numerous sky-scrapers, bridges, roads, underground tunnels, …


This paper discusses the suitability of producing concrete with 100 % recycled aggregate to meet durability and strength requirements for different applications. Aggregate strength, gradation, absorption, specific gravity, shape and texture are some of the physical and mechanical characteristics that contribute to the strength and durability of concrete.


The outcome of the study shows that the recycled aggregates are more heterogeneous and have a high capacity of water absorption, but which still respects the current standards of concrete. The need for additional water has been observed for recycled aggregates-based concrete so …


This is the case with CDW, which is mainly composed of these minerals. These can also include recycled concrete aggregates, especially the fine fraction rich in old, hydrated cement paste and other waste coming from cementitious products . Another field of application of RA is the alkali-activated cement, so-called geopolymers.


2.2.Experimental mix design method applied to the recycled concretes. The recycled concrete experimental mix design in this research was performed according to the method described by Monteiro et al., except for the adaptation made to determine the workability of the mixtures evaluated.Instead of using slump test, as described by the mix design method, in the present work …


Concrete Workability Definition. The workability of concrete refers to how easily freshly mixed concrete can be placed, consolidated and finished with minimal loss of homogeneity. In other words, it refers to how 'workable' the concrete is, how easily it can be manipulated without its strength being compromised.


Therefore, in this paper, the effect of hydroxypropyl methylcellulose (HPMC) on the workability, mechanical properties, and durability of concrete …


Recycled concrete, or crushed waste concrete, is a feasible source of aggregates and an economic reality, especially where good aggregates are scarce. Conven-tional stone crushing equipment can be used, and new equipment has been developed to reduce noise and dust. Aggregates must conform to certain standards for


tensile strengths of concrete made with recycled concrete aggregates (RCA). The target concrete compressive strengths were 30, 45, and 60 MPa, whereas the basalt fibers had a length of either 20 or 43 mm. The addition of BF significantly decreased the workability, slightly improved the compressive strength, and


The second study examines how the workability and compressive strength characteristics of concrete mixes are affected when varying amount of recycled concrete fines are used as cement replacement. Experimental procedures for both studies involved the breaking and crushing of cast concrete blocks to produce recycled materials.