🕑 Reading time: 1 minute Alkali aggregate reactions (AAR) occur when aggregates in concrete react with the alkali hydroxides in concrete producing a hygroscopic gel which, in the presence of moisture, absorbs water and causes expansion and cracking over a period of many years. This alkali-aggregate reaction has two forms, namely: Alkali-silica …
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A concrete mixture available in the literature (Poon et al., 2004) is chosen and natural fine aggregate, natural coarse aggregate and both natural fine and coarse aggregate are replaced with recycled fine aggregate, recycled coarse aggregate and recycled fine and coarse aggregate, respectively in a range of 0–90% with the step of …
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The effect of pumping on the prepacked aggregate concrete (PAC) with a w/c ratio of 0.5 was studied, ... Another crucial mechanical property, whose variation due to pumping is of high interest, is the elastic modulus. Regardless of the material compositions or pumping distances, all the samples lose some of their elastic moduli after horizontal ...
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The durability of steel slag coarse aggregate concrete limits the application of steel slag in construction engineering. This study carried out the erosion test, material mechanics test, and microscopic test of steel slag coarse aggregate concrete under the action of different mass fractions of sulfate solution to investigate the effect law and …
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The pervious concrete mixture consists of 15%, 20%, and 25% of fine aggregate variations and standard rodding, proctor Hammer, and concrete vibrator as the compacting methods used. The amount of cement used on each mixture is 360 kg/m 3, w/c = 0.3, and admixture as much as 2.8% of the cement used. The slump, compressive …
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This paper investigates the effect of cement by type and source on strength as a function of supplementary cementitious material (SCM) replacement and aggregate type. This was accomplished by ...
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This may be due to the fact that 30 % of coarse aggregates are replaced by RCA, enabling the HPC to store more water for internal curing, thus resulting in more cement hydration products. Swelling may produce cracks on HPC surface, which can potentially damage the concrete structural integrity.
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6.2—Definition of lightweight-aggregate concrete 6.3—Low-density concretes and associated aggregates 6.3.1—Structural lightweight concrete and associated aggregates 6.3.2—Moderate-strength lightweight concrete and associated aggregates …
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Although, much research has been conducted on the use of recycled aggregates in structural concrete, a large amount of these materials are used in non-structural concretes or used as road bases [22].Due to the wide variation in the properties of concrete containing recycled aggregate, engineers still prefer the use of …
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Natural aggregates replaced partially or fully with recycled concrete aggregates (RCA) in preparing concrete has emerged as a sustainable construction technique and investigating the properties of such concrete has already been the focus of number of published studies. However, limited data are available for the case of recycled …
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1. Introduction. Lightweight concrete (LC) has been progressively used in structures such as large-span bridges, high-rise buildings and offshore oil platforms, owing to its superior characteristics in density, specific strength and durability [1,2].Partially or entirely replacing normal weight concrete (NWC) with LC produces considerable …
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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 …
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Notably, due to the variation in aggregate sizes, the compressive strengths exceeded those of the 12 mm aggregate size. Figure 8 Effect of laterite soil ratios on …
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Regarding FPZ features of RCAC, it was found that the utilization of RCA has a definite impact on FPZ of concrete due to the existence of loose old mortar, that is, more and ... Fig. 5 depicts the recorded load-CMOD curves of concrete with various aggregate combinations. The variation of load and CMOD shows typical quasi-brittle fracture ...
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1.1. Aggregate Shape. Ueno, A. investigated [] the influence of the particle shape of coarse aggregates on two optimal fine to total aggregate ratio values based …
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Due to the presence of attached old mortar in recycled concrete aggregate (RCA), the elastic modulus of the prepared recycled aggregate concrete (RAC) is generally lower than that of normal ...
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HSC experiences a rapid loss of tensile strength at higher temperatures due to development of pore pressure in dense microstructured HSC [].The addition of steel fibers to concrete enhances its tensile strength and the increase can be up to 50% higher at room temperature [67, 68].Further, the tensile strength of steel fiber-reinforced concrete …
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After demolition of old roads and buildings, the removed concrete is often considered worthless and disposed of as demolition waste. By collecting the used concrete and breaking it up, recycled concrete aggregate (RCA) is created (Fig. 1).This paper focuses on coarse RCA which is the coarse aggregate from the original concrete that is …
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Concrete materials. Table 1 depicts the properties of 53-grade ordinary Portland cement (OPC) used in the study (IS 269:1989) [].River sand and river gravel confirming zone II were used as fine natural aggregate (NFA) and NCA. The 30-year-old building demolished at the institution was chosen as the study site; concrete fractions at …
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While the normal aggregate concrete has a 28-day compressive strength of 41.9 MPa, the strengths of the recycled aggregate concretes are generally similar and fall between 32.7 MPa (for type-R2) and 28.8 (for type-R3). This result shows that the varying properties of the recycled. Table 2 Concrete mix proportions and fresh properties.
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🕑 Reading time: 1 minute Adjusting the slump of concrete is a part of the concreting process, which the contractors should manage properly and cautiously. The concrete slump variation from one transit mixer to another is generally due to aggregate moisture content, concrete temperature, mixing process; and time of delivery, waiting, and unloading. …
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Twelve (12) cubes (150x150mm) of each type of coarse aggregate were cast for 7, 14, 21, and 28 days to determine their compressive strengths. Quartzite was found to have the highest average ...
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a, and a. in cement stone and aggregate due to 1 deg C of temperature variation have been compiled and are shown in Figures 1, 2, and 3. Because temperature variation may be considered as an instantaneous effect, zero rate of creep ip has been assumed. The important relationships on the basis of the elasticity equations are given below: 1.
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Download Citation | Mechanical properties of recycled aggregate concrete surface treated by variation in mixing approaches | Increased demand for natural aggregates (NA) due to infrastructural ...
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1. Introduction. Increasing urbanization is constantly raising the demand for concrete globally. As one of the essential building materials, both the annual production and consumption of concrete have reached more than 30 billion tons in recent years [1].Concrete production has a negative effect on the global warming process, with over …
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In this study, recycled aggregate concrete (RAC) specimens at different recycled coarse aggregate (RCA) replacement percentages were prepared based on similar compressive strength. The damping property of the RAC was tested by the suspension method. The frequency, the damping ratio and the correlation analysis of each factor …
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Recycled concrete aggregates (RCA) sourced from waste concrete are a sustainable alternative to natural crushed stone aggregates. ... Variation of workability due to addition of RCA. 3.2. Fresh density. The density of concrete is found to decrease with the increase in replacement ratio of coarse aggregate and is shown in Fig. 2. For concrete ...
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Inherent color variations is the difference in color between two lifts. It is caused by using cements form different plants. A similar effect is obtained if the water/cement ratio is different for each lift. Aggregate transparency is when the dark areas of the mottled effect correspond with pieces of coarse aggregate near the form face.
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Correcting for Water in Aggregate . Concrete is made of three main materials: aggregate, cement, and water. In automated production environments, these are normally measured by weight. As the aggregates are stored outside and subject to environmental conditions, their moisture can vary, for example, with sand, between 1 …
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Non-conventional aggregate-based concrete may exhibit different thermal responses compared to conventional concrete due to variations in mineral composition, …
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