Optimization of Aggregate Production Circuit through Modeling of Crusher Operation

The paper concerns investigation of the effect of impact crusher operation on selected qualitative characteristics of mineral aggregate products. Qualitative characteristics of crushing products in terms of size reduction ratio and fine particles contents were analyzed from the point of view of operational parameters of the impact crusher. An investigative program was carried out on a plant scale and two primary parameters of the impactor were analyzed: velocity of the crusher rotor and the width of the outlet gap. The models of the crushing device operation were built separately for each type of the tested material, as well as for general conditions.

Mechanical properties of steel slag replaced mineral aggregate for road base/sub-base application based Vietnam and Japan standard

Steelmaking slag is one of the most massive industrial by-products generated during steelmaking processes. This paper presents the current steelmaking slag production status and its potential to use as mineral aggregates in base/sub-base layer of road pavement. The mechanical properties of steelmaking slag were confirmed by the test method specified in Vietnam specification. The volume stability test of the slag was conducted based on JIS A 5015-2018 (Japanese Industrial Standard: Iron and steel slag for road construction). From the results, it was confirmed that steelmaking slag can satisfy all the mechanical requirements specified in Vietnam specification and the requirements regarding stability specified in JIS A 5015-2018. In addition, it was found that the elastic modulus of steelmaking slag applied as a base or sub-base layer in pavement was higher than that of the conventional graded aggregate made from mineral aggregate. Therefore, the thickness of pavement can be reduced by using steelmaking slag, and the construction cost can be lower.

THE EFFECT OF SEA WATER IMMERSION ON BUTON ASPHALT (AS-BUTON) MIXTURE

One of the causes of flexible pavement damage is being submerged in water with a high acidity, such as seawater. To overcome this condition, a study on the use of buton asphalt (as-buton) was conducted. The advantages of as-buton are that it has higher adhesion and is more resistant to temperature changes. As-buton modification by mixing Lawele as-buton Southeast Sulawesi with oil asphalt pen 60/70. This study focuses on determining the effect of the addition of as-buton to the modified asphalt mixture and the effect of seawater immersion on as-buton mixture based on the Marshall characteristic test. The percentage by weight of as-buton used is 5%, 7.5%, and 10%. The immersion was carried out in freshwater and seawater immersion for up to 24 hours at a temperature of 30°C. The result of this study show that the addition of as-buton increase the value of stability, void in mixture, Marshall quotient (MQ), and void in mineral aggregate, but reduce the flow, void filled with asphalt, and density. The increase of stability and MQ value in seawater-immersion due to the addition of as-buton was higher than that in freshwater. The stability value of the 10% modified as-buton mixture in freshwater-immersion increased by 169.338 kg (14.61%) and in seawater-immersion increased by 1261.669 kg (55.65%). The flow value in freshwater-immersion decreased by 1.9 mm (25.33%) while in seawater-immersion decreased by 1 mm (14.08%). For further research, variations in the addition of as-buton will be carried out to produces a modified asphalt mixture.

Recycling of WEEE Plastics Waste in Mortar: The Effects on Mechanical Properties

This work focused on the recycling of WEEE plastic waste as a partial substitute for aggregate in light mortars. The plastic mix, provided by the IREN group, was used as a replacement of aggregate in 15, 30, 45, 60, 75, and 90%vol in mortars. Worsening of the mechanical performance of around 50% was detected already at only 15%vol of mineral aggregate substituted with plastic waste. The explanation of this phenomenon was found in both the scarce mechanical properties of the used plastic and in the poor adhesion between matrix and plastics that resulted in extra-porosity formation, as also demonstrated by comparing the results with several models in the literature. However, the use of plastic waste as a partial replacement of natural aggregate contributes to the preservation of natural resources and, in any case, does not limit the application of these materials in non-structural applications.

Effects of Chemical Dispersant on the Surface Properties of Kaolin and Aggregation with Spilled Oil

After oil spills occur, dispersed oil droplets can collide with suspended particles in the water column to form the oil-mineral aggregate (OMA) and settle to the seafloor. However, only a few studies have concerned the effect of chemical dispersant on this process. In this paper, the mechanism by which dispersant affects the surface properties of kaolin as well as the viscosity and oil-seawater interfacial tension (IFTow) of Roncador crude oil were separately investigated by small scale tests. The results indicated that the presence of dispersant impairs the zeta potential and enhances the hydrophobicity of kaolin. The viscosity of Roncador crude oil rose slightly as the dosage of dispersant increased while IFTow decreased significantly. Furthermore, the oil dispersion and OMA formation at different dispersant-to-oil ratio (DOR) were evaluated in a wave tank. When DOR was less than 1:40, the oil enhancement of dispersant was not significant. In comparison, it began to contribute when DOR was over 1:40 and the effect became more pronounced with the increasing DOR. The adhesion between oil droplets and kaolin was inhibited with the increasing DOR. The size ratio between oil droplets and particles is the significant factor for OMA formation. The closer the oil-mineral size ratio is to 1, the more difficultly the OMA forms.

Pengaruh Rendaman Air Laut Pasang Surut terhadap Campuran Lapis Aspal Beton AC-WC dengan Modifikasi Steel slag Ramah Lingkungan

Road pavement near coastal area has greater chance for seawater immersion. Along the road of Pantai Utara especially on Jalan Kaligawe Raya, Semarang, Jawa Tengah, tidal seawater flood often occurs. Road pavement that is immersed by water is potentially damaged since water is one of the causing factors of damage in road pavement. Recurring weight also will decrease the design life and the road degrades faster. The buildup of unused waste from steel factory can be an alternative material for modified asphalt mix. The test result of 6, 12, and 24 hours seawater immersion indicated poor marshall characteristic value marked by the decrease of density value, VFA (Void Filled Asphalt), stability, and MQ (Marshall Quotient), and indicated the increase in VIM (Void In the Mix), VMA (Void in Mineral Aggregate), and flow.

SIFAT VOLUMETRIK CAMPURAN LASTON MENGGUNAKAN ASPAL MODIFIKASI GETAH PINUS DAN LIMBAH STYROFOAM

Sifat volumetrik campuran pada laston merupakan salah satu faktor yang menentukan durabilitas (keawetan) lapis perkerasan jalan. Untuk meningkatkan keawetan lapis perkerasan jalan dan mengurangi dampak negatif terhadap lingkungan dapat dilakukan antara lain melalui modifikasi aspal dengan getah pinus dan limbah styrofoam. Tulisan ini bertujuan untuk mengkaji sifat volumetrik campuran laston menggunakan aspal modifikasi getah pinus dan limbah styrofoam tersebut. Sifat volumetrik campuran laston yang dikaji adalah rongga dalam campuran, rongga di antara mineral agregat, rongga terselimuti aspal, density dan bulk specific gravity. Pada penelitian ini digunakan agregat bergradasi rapat yang dicampur dengan aspal modifikasi pada suhu 155 oC dan dipadatkan 75 kali pada kedua sisinya. Pada seluruh benda uji, prosentase limbah styrofoam yang digunakan adalah 6% sedangkan getah pinus sebesar 0%, 1%, 2% dan 3% terhadap berat aspal modifikasi. Hasil penelitian menunjukkan bahwa campuran laston yang menggunakan aspal modifikasi getah pinus menghasilkan nilai VFB, density dan bulk specific gravity lebih besar serta nilai VIM dan VMA lebih kecil dibandingkan dengan campuran yang menggunakan aspal modifikasi limbah styrofoam. Dengan nilai VIM dan VMA lebih kecil, campuran yang menggunakan aspal modifikasi getah pinus menghasilkan daya ikat lebih kuat sehingga memiliki durabilitas lebih tinggi. Ditinjau dari persyaratan laston sebagai lapis aus pada perkerasan jalan, penggunaan getah pinus dan limbah styrofoam sebagai modifier aspal memenuhi persyaratan volumetrik campuran. Volumetric properties of asphalt concrete is important factor to determine the durability of road pavement. Improvement the durability of road pavement and reducing negative impact of the environment can be done by using modified asphalt. This article aims to know the volumetric properties of hot mix asphalt using pine resin and waste styrofoam as asphalt modifier. The volumetric properties include voids in mix, voids in the mineral aggregate, voids filled with bitumen, density and bulk specific gravity. In this study, a continuously graded aggregate was used and mixed with modified asphalt at 155 oC and compacted with 75 blows on both sides. The percentage of waste styrofoam was 6% whereas the percentages of pine resin where 0%, 1%, 2% and 3% by weight of modified asphalt. From the analysis, it can be concluded that asphalt concrete containing pine resin as modifier strengthen the binding between asphalt and agregate, due to increasing value of voids filled with bitumen (VFB), density and bulk specific gravity. Durability of asphalt concrete using pine resin as modifier was higher than that of asphalt concrete using waste styrofoam because of decreasing value of voids in mix (VIM) and voids in the mineral aggregate (VMA). Based on the specification of asphalt concrete wearing course, the use of pine resin and waste styrofoam as asphalt modifier has fulfilled volumetric properties requirements.