Advanced Materials Research Vol. 723

Abstract: To explain the interactive effect between asphalt and fillers in the asphalt mastic, it is probably to start with an assessment of the rheology properties, since asphalt mastics are viscoelastic materials. In this study, firstly prepare the asphalt mastics with different dosage of limestone filler, and the volume fractions of fillers were 0, 14, 24, 32, 39 and 45%. And then, the same asphalt is mixed with different fillers, such as cement and hydrated lime, and the volume fractions of fillers were 18, 23, 28and 33%. DSR test was conducted on all of the asphalt mastic specimens to measure the complex shear modulus G* at different temperature. The volume filling effects and interaction between asphalt and filler are discussed on the analysis of complex shear modulus coefficient and Nielsens model model. It is obviously that G* of asphalt mastics decrease with the test temperature, but increase with the volume fraction of filler. A function relation between complex shear modulus coefficient and volume fraction of fillers is established, and the interaction coefficient α is proposed. For limestone, cement and hydrated lime filler, the interaction coefficient α values are 0.301, 0.317 and 0.429 respectively. Based on Nielsens model and DSR test data, the Einstein coefficient K_E is calculated, and Einstein coefficients are 3.761, 5.09 and 7.44 for asphalt-limestone mastic, asphalt-cement mastic and asphalt-hydrated lime mastic respectively. Both the interaction coefficient α and Einstein coefficient K_E can be used to represent the interaction between asphalt binder and filler. The bigger value means the better interaction.

Abstract: This paper has studied the different dosage of cement mixed with different proportions of gravel. Through the compaction and unconfined compressive strength test and economic analysis, and finally determined that the gravel mixed with content is 30% and the cement dosage is 3%. The study also shows that by adding a certain amount of gravel instead of powder is feasible. The same cement doses adding macadam mixture, unconfined compressive strength is higher than stable powder. The study has solved the shortage of raw materials of construction, saving a lot of money, and has important engineering significance. Keywords: cement stable powder; crushed stone; unconfined compressive strength; cost analysis;

Abstract: The paper discusses the results of a laboratory investigation aimed at analyzing the rutting susceptibility of high performance asphalt concretes, made with three different bituminous binders and four types of artificial and recycled aggregates (steel slags, glass wastes, municipal solid waste incineration bottom ash and coal ash), used in partial substitution of the natural limestone. The experimental study has been focused on the characterization of the physical-mechanical properties of the marginal materials, as well as on the volumetric mix design and the permanent deformation evaluation (by means of Creep Recovery Tests, Repeated Load Axial Tests, Wheel Tracking Tests) of bituminous mixtures for road and airport asphalt concrete base courses. Because the requisites for acceptance in the Italian Specifications and Standards have been satisfied and given the positive mechanical performance (indirect tensile strength at 25°C on dry and wet samples up to 1.27 MPa and 1.07 MPa respectively), it has been verified that the marginal aggregates investigated can be used as substitution of the lithic materials in the base courses, also with very high content (up to 70% on the weight of the aggregates).

Abstract: This study explored the stiffening behavior of the cement pastes using a new vibration folk technique. The viscosity evolutions of the cement pastes were evaluated using either a rotational viscometer or a tuning fork vibration viscometer. Results showed that the viscosities were increased with hydration time. The viscosity increases of the cement pastes measured by the vibro-viscometer were more stable than those measured by the rotational viscometer. In addition, the subtle changes in the paste viscosities during the very early hydration were well detected by the vibro-viscometer. The new vibration folk technique has been shown a useful tool to characterize the microstructure changes in the early cement pastes.

Abstract: This investigation indicates the effects of freeze-thaw cycles on the strength development and durability of lightweight aggregate concretes. Two lightweight aggregate concrete, one normal concrete and one reactive powder concrete were used in this study, and total four types of concrete mix were named NC, LWC1, LWC2, and RPC. Before and after freeze-thaw test, the samples were evaluated by the compressive strength, fflexural strength, and impact abrasion tests. The test results show that steady decrease in compressive and flexural strength after freeze-thaw testing for most concrete specimens. The lightweight aggregate used in the LWC1 mix for this laboratory study had a good freeze-thaw performance history, but the LWC2 mix with lightweight aggregate approaching the 24-hour water absorption had a bad result. It might be due to the void volume required to release hydraulic pressure developed during cyclic freezing.

Abstract: In this study, the 50°C warm water is applied to accelerate curing of concrete and to increase the design strength to 210kgf/cm² (3000psi), 280kgf/cm² (4000psi), and 490kgf/cm² (7000psi) by using water/cement (w/c) ratio of 0.6, 0.5, and 0.35 respectively. The result shows that it takes only 2~5 days to reach the design strength with warm water curing instead of 28 days by standard curing. Three type of specimens may reach 1.0~1.05 times of target strength. As a result, a modified coefficient factor for design of concrete strength can be predicted more accurately and much earlier during curing process of the concrete.

Abstract: Moisture damage is one of the main forms of early failure in the pavement. Water can be released from the road structure by setting porous concrete permeable base. The common construction technology for porous concrete is traditional vibration compaction, which is helpful for the strength formation of the base. However, it is unhelpful for the stability and smoothness of the base during the construction. In this study, compaction-free porous concrete (CPC) permeable base was proposed, which can not only satisfies both porosity and the structural strength, but also guarantees the stability and the smoothness of the base during construction. The performance of normal porous concrete (NPC) and CPC, such as strength, drainage capacity, shrinkage and frost resistance, were studied in the paper. The laboratory tests show that all of them have good performance. In addition, the field evaluations, such as strength, drainage capacity, deflection, smoothness of the base, were tested. The results show that both of NPC and CPC have good drainage capacity, and the strength of NPC is higher than CPC, but the smoothness of NPC is weaker than CPC.

Abstract: An investigation was conducted to determine the effects of temperature, compaction water content, and compaction efforts on soil suction of two expansive subgrade soils. For this purpose, two expansive soils were statically compacted at target water contents ranging from 5% to 20%. This made it possible to explore a broad spectrum of compaction conditions. Filter paper method and thermocouple psychrometer were used to measure soil suction at temperatures ranging from 10°C to 60°C. Experimental results show that compaction water content, compaction effort, and temperature have influences on soil suction. As water content increases, the influences of compaction effort and temperature on suction become less significant. Finally multiple regression formulations for predicting the soil suction of as-compacted clayey soil were established.

Abstract: Reservoirs in Taiwan have been experiencing severe siltation problems due to unfavorable environmental conditions and numerous harmful human factors. This research conducts a bench scale experimental study to explore the potential of using reservoir siltation (RS) in controlled low strength material (CLSM) particularly for subgrade applications. Test results show that RS can be used for producing of acceptable CLSM through proper mix design procedures. Considering the requirements of pavement subgrade constructions, this study recommends a water/solid ratio of 0.7~0.8 and a cement/water ratio of 0.4~0.5 can be used for the design. The study proposes a promising solution to reuse reservoir siltation, save natural resource of granular fill, and ensure the quality of pavement subgrade constructions in most cases.

Abstract: In Buton Island, an island located in South-East Sulawesi Island in Indonesia is found about 700 million tons natural rock asphalt (NRA) which have not been maximally utilized yet. Buton-NRA contains 20 to 30% of bitumen. This paper reported the first part of the research on utilizing of Buton-NRA as additive of bitumen binder in hot mix asphalt (HMA) mixtures. Amount of 15, 20, 25, 30, 35, 50, and 65% of very fine of Buton-NRA was added into the bitumen, resulted Buton-NRA-Bitumens binder. Penetration and softening point test was conducted to get penetration index (PI) value, an index to determine the temperature susceptibility of the binder. The results show that the Buton-NRA-Bitumens binder has low temperature susceptibility. Use as binder in HMA mixtures also shown that the Buton-NRA-Bitumens binder can improve the performance of the mixtures. Marshall Stability and stiffness of the mixtures is higher compare to that of base bitumen binder, especially Buton-NRA-Bitumens binder with 50% of Buton-NRA, Marshall Stability reach 2374kg and stiffness 311kg.mm, while HMA mixtures with base bitumen (0% Buton-NRA) only has 1294kg of Marshall stability and 169kg/mm of stiffness.