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Compared with compression crushing, impact crushing will create more fines within the circuit, which will cause greater wear if processing abrasive material. This is why rocks with lower silica content …
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The coarse RCAs with a maximum particle size of 20 mm were supplied from ResourceCo in South Australia. Fine aggregates were river sand (nonreactive) with a maximum particle size of 2 mm and multicolor crushed glass sand with a maximum particle size of 1.19 mm. Figure 1 shows the aggregates particle size distributions. The glass …
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Operator isolation for crushing machines includes using either an enclosed booth or a remote control station. Operators using crushing machines with enclosed cabs can limit their silica exposure by staying inside the cab during crushing operations. The enclosed cab must: • Be well-sealed and well-ventilated using positive pressure.
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Request PDF | On Jul 1, 2023, Shaohua Li and others published Effects of amorphous silica on mechanical contribution of coarse aggregates in UHPC: From micromechanics to mesoscale fracture and ...
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where l is the length, d FIER is the equivalent diameter, A is the cross-sectional area, and Ψ is the perimeter of the fiber cross-section. The aspect ratio was approximately 24 36.. The Density ...
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It was found that 20% of cement can be replaced with waste glass of 20 μm without detrimental effects on the mechanical properties. Replacements higher than 30% can cause negative impacts as insufficient amounts of CaCO 3 remain to react with the silica from the glass, known as the dilution effect. As the fine aggregate replacement …
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In China, an estimated 23 million workers are exposed to silica dust while in India, about 10 million workers are exposed. 1 Similarly, in the United States, 2.3 million workers are estimated to be exposed to silica dust with 1.85 million of them in the construction sector. 2 Recent studies have shown increased morbidity and mortality …
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Poole [1] has suggested that it is incorrect to consider rock type (e.g., basalt) as a criterion for an aggregate's ASR potential; and instead, attention should be focused on the mineral constituents of the rock. The thermodynamic stability of silica minerals decreases as the degree of microstructural disorder increases. Amorphous SiO 2 (e.g., …
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Alkali-Silica Reactivity (ASR) is a chemical reaction between alkalis in the cement fraction of concrete mortar and certain types of siliceous aggregates. Resulting in the expansion and cracking of the concrete. There are at least two types of interactions between cement components and …
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1. Introduction. Occupational exposure to crystalline silica dust (SiO 2) has become one of the most common and serious hazards for artificial stone workers.According to recent studies, a large number of workers are exposed to this mineral dust throughout the world, with more than 3.2 million workers in Europe and more than 2 million in the United …
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2.1 Materials. The cement used is this study was a P.O 42.5 ordinary silicate cement with the basic parameters listed in Table 1 and the chemical composition is …
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The test is completed in 16 days, making it more useful for short-term screening of aggregate sources. ASTM C1567, Determining the Potential Alkali-Silica Reactivity of Combinations of Cementitious Materials and Aggregate (Accelerated Mortar-Bar Method), identifies mix designs that will mitigate the effects of reactive aggregates. Various ...
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Aggregate crushing value (%) _ 11.75: 19.41: BS 812-110 [26] Aggregate impact value (%) _ 8.15: 15.24: BS 812-112 [27] Max. aggregate size (mm) 4.75: 12.5: 12.5: ... However, filling and pozzolanic effects of silica fume particles and carbon fibers crack bridging ability caused significant rise in elastic modulus of concrete mixes. By ...
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The coarse aggregates obtained by different crushing mechanisms (jaw and impact crushers) show very similar characteristics in terms of binder content assessed by acid leaching (27.5 and 26.6 wt.%), water absorption (8.76 and 9.75 wt.%) and porosity (18.6 and 20.2 vol.%).Thus, it is not possible to conclude that any of these mechanisms …
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Crystalline silica can be released into the air from cutting, grinding, drilling, crushing, sanding, or breaking apart many different materials. Silica is a well-known occupational hazard and has also been …
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This paper presents the effects of silica fume and steel fiber on the mechanical properties and impact behavior of recycled aggregate concrete containing two types of recycled coarse aggregates ...
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Hence, in this context, to reduce global warming, the usage of cement can be minimized by replacing it with other materials such as fly ash, silica fume, red mud, ground granulated blast furnace slag, metakaolin, rice husk ash, corncob ash, sugarcane bagasse ash, etc. QRD is a calcium-rich waste material from the rock crushing industry that is ...
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The use of Silica Fume (SF) in short period of time had one of the most dramatic impacts on the industry's ability to routinely and commercially produce SF modified concrete of flowable in nature ...
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In the crushing process, blocks from the quarry are fragmented until reaching a commercial dimension to use in the civil construction [24], [25]. This process can be realized by utilizing several crushers, with different comminution mechanisms, such as compression or impact, which affects the morphology of the particles produced [25], [26].
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The crushing characteristics of coarse aggregates for asphalt concrete were investigated under static and dynamic aggregate crushing value tests (ACVTs).
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19.1.1.2. Agro-wastes-based pozzolans. The cement production industry is regarded as the major source of greenhouse gas discharge (Mikulčić et al., 2016).As cement is perhaps the most environmentally unfriendly concrete component, its usage is generally minimized by partial substitution with industrial wastes like fly ash, silica fume, …
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This paper investigates the effect of the bauxite sand and coarse aggregate on the quasi-static mechanical properties and resistance against high-velocity projectile impact of cement composites with 28-day compressive strengths from 34.2 to 197.2 MPa, in comparison to that of the siliceous sand and granite coarse aggregate.
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Present research involves determining the effects of a proposed novel nano-silica prioritized-steam-treated recycled concrete aggregate (RCA) on microstructural, mechanical, and durability aspects of concrete incorporated with waste ceramic powder (WCP). The study on novel nano-silica prioritized-steam-treated …
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Silica fume is one of the construction materials, even though possess numerous advantages when used in concrete mixtures. Also it has disadvantages that are mentioned by numerous researchers [[33], [34], [35]].The existence of extremely sensitive amorphous silica in SF significantly affects the strength because of its reaction with CH …
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The required fractions for AMBT were produced using large and small jaw crushers as well as a disk pulveriser. After crushing, RA were washed based on the Adams et al. method. In CMBT, the batch water was corrected for aggregate absorption during mixing and the alkalis were boosted until 1.5% Na 2 O eq in some mixes. After 24 h …
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Evaluation of blast efficiency in quarrying of aggregate stones is one of the most important decisions that should be made by quarry operators for productivity assessment. ... (OELs) for respirable dust and respirable silica are 3.00 and 0.05 mg/m 3 ... Workman L, Eloranta J (2003) The effects of blasting on crushing and grinding …
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This study explores the effect of high content of silica sand as a partial replacement for fine aggregate for concrete making in construction purpose. In this present research four types of silica sand …
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In this study, the influence of CO 2 curing treatment on the alkali-silica reaction (ASR) of mortar bars containing recycled glass was investigated. The ASR expansion results according to ASTM C1260 demonstrated that a short period (3 h) of CO 2 curing could fully suppress the ASR expansion. Apart from mechanical strength …
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Compliance and Safety for Silica. If you work in a profession that involves crushing asphalt, concrete or rocks (e.g. mining, milling or construction), you're probably aware of OSHA's tightening Permissible Exposure Limit (PEL) for respirable crystalline silica (Table 1 of OSHA Standard 29 CFR 1926.1153).The new standard – 50 micrograms per cubic …
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Alkali-silica reaction (ASR) is a deleterious reaction that occurs between alkalis from the cement and reactive minerals of the aggregate, forming a gel that swells …
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The comparison of the effects of silica fume type and content on the axial tensile strength and ultimate tensile value is shown in Fig. 5, which indicates that silica fume content has certain impact on the axial tensile strength and ultimate tensile value of LHP cement concrete, and the strength and tensile value increase with the increase of ...
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The characterizing attributes of the Wargal Limestone and Chhidru Formation include lower values of soundness, Los Angeles abrasion, aggregate impact, aggregate crushing, and water absorption due ...
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This study proposed a novel method of crushing glass aggregates to reduce the alkali-silica reaction (ASR). Glass aggregates were crushed while immersed in …
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In some aggregate, the active silica constituents react with alkalis in the cementitious materials, producing alkali-silica gel. The reaction product (gel) is …
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The Effects of Bit Wear on Respirable Silica Dust, Noise and Productivity: A Hammer Drill Bench Study. Increasing bit wear was associated with increasing respirable silica dust and noise and reduced drilling productivity. The levels of dust and noise produced by these experimental conditions would require dust capture, hearing protection, and ...
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The materials listed in Table 1 were first mixed in a mixing machine for 120 s to get a slurry with nice dispersion. The ORA was then added into the strengthening slurry, and all of the materials were mixed three times. Each mixing lasted for 3 min, and the interval between two adjacent mixings was 1 min. Afterwards, the redundant slurry was …
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