Applied Mechanics and Materials Vol. 776

Abstract: The World Earth Summits in Rio de Janeiro, Brazil and Kyoto, Japan in 1992 and 1997 respectively, have made it clear that uncontrolled increased emission of greenhouse gases to the atmosphere is no longer environmentally and socially acceptable for sustainable development. The increase of cement production will affect the environmental preservation, natural conservation and increase the CO₂ emission, which is one of the primarily gases that contribute to the global warming. The use of ground granulated blast furnace slag (ggbs) to replace a part of Portland cement in concrete can reduce the CO₂ emission. It also can provide significant benefits to concrete properties, such as increase the workability and durability of concrete. The early strength of ggbs concretes that had been cured at standard curing temperature (20°C) were slower than that of concretes with Portland cement only, cured at the same temperature. However, there are some indications show that curing the ggbs concrete at elevated temperatures will significantly enhanced the early age strength of the concrete. The objectives of this research are to find out the effect of curing temperatures and levels replacement of Portland cement by ggbs on the strength development of concretes. The levels of ggbs to replace Portland cement were 0, 20, 35, 50 and 70%, while the curing temperatures were 20°C, 50°C and adiabatic curing. The concrete cubes were tested at ages: 6 and 12 hours, 1, 2, 4, 8, 16, 32, 64, 128, 256 and 365 days. The results showed that curing the ggbs concrete at temperatures higher than standard curing temperature, increased the strength development of the concrete at early ages.

Abstract: Construction of road pavement requires large amount of materials. Effort to incorporate secondary or lower quality materials had been done. This is particularly attractive for constructing lower trafficked road. Within this experiments waste polypropylene (PP) plastic was used as partial aggregate substitute in sand sheet asphalt mixture, with objective to evaluate its properties. The amount of plastic used was 10%, 20%, and 30%. The aggregate and plastic were proportioned. The aggregate were heated to around 155-160 °C, then pre-melted asphalt and the waste plastic were added then re-mixed until the asphalt evenly coat the materials. The mixture was compacted at 2x50 Marshall blows. It was found that at 8.5% optimum asphalt content, and at all range of plastic content the stability was 277.41-283.49 kg (> 200kg), Void in Mixture within range (3-6%), Void in Mineral Aggregate >20% and Void Filled with Bitumen >75%, all met the Indonesian specification. However the flows were > max 3mm and Marshall Quotient < min 80 kg/mm (did not specification). When incorporating plastic, only limited amount of plastic (less than 10%) can be incorporated to meet the specification.

Abstract: Environmental and climatic factors directly affect the temperature of asphalt pavement layers. Air temperature is one of the most important environmental factors that significantly affect the temperature distribution profile of asphalt pavement layers. It is important therefore, to comprehend the asphalt strength characteristics because of the differences in asphalt pavement designs. This study was conducted in ​​tropical area with high humidity in Indonesia. A testing method was carried out to measure both temperature and humidity using thermocouples equipped with data logger and an application program of SAGA Technology. Measurements were taken for consecutive seven sunny days in July 2014. The average values obtained ​​for hourly air temperature and humidity were ranging from 24.92 to 36.98 °C and from 50.31 to 83.69% respectively. Meanwhile, pavement surface temperatures measured at 0, 20 and 65 millimeters depths were varied from 25.29 to 45.65 °C, from 25.37 to 43.59 °C, and from 26.70 to 38.54 °C respectively. Both air and asphalt pavement temperatures are sharply increased from 10:00 a.m. to 02:00 p.m. and are gradually decreased afterward.

Abstract: Slurry Seal is an impermeable non-structural thin layer that is used for pavement maintenance consisting of a cold laid mixture of asphalt emulsion with continuous graded fine aggregate, mineral filler, water and other added ingredients. Ordinary Portland Cement (OPC) as the main filler in the application of slurry seal. Due to the relatively high cement prices and the pollution control for the environment; it is required to maintain the quality of the slurry by using a combination of OPC and LCFA (Low Calcium Fly Ash). This research was conducted to determine the value of consistency, setting time and indirect tensile strength (ITS) of slurry seal containing LCFA. A consistency testing used to obtain optimum moisture content to produce the sample for the rest of the test. The results show that with the addition of 5% water for pre-wetting and subsequently 10% of water content, the mixture provide appropriate consistency as required by highways standard. The time settings also meet the requirements of highways standard between 15 to 720 minutes for all types of mixtures. The mixture with composition of 50% OPC and 50% LCFA is considered as an ideal mixture at the optimum density value of 1.769 g/cm³, porosity of 9.55% and the indirect tensile strength of 30.99 kPa. It could be concluded that fly ash can be used as OPC partial replacement and enhance the properties on slurry seal application.

Abstract: Thin Hot Mixture Asphalt Concrete Overlays (THMACO’s) are comprised of a thin layer less than one inch hot mix asphalt concrete layer and a binder material/tack coat. The uses of thin layer are necessary to compromise with the environment issue especially to protect the natural resources and save the energy used during asphalt construction. THMACO’s can be used as preventative maintenance on pavement preservation or as a new surface on a pavementconstruction. This layeris usually regarded as non-structural layer at pavement design. However, this paper presents the structural assessment of this materials and their comparison to the conventional asphalt concrete mixtures. This research was conducted based on indirect tensile strength (ITS), unconfined compressive strength (UCS) and indirect tensile stiffness modulus (ITSM) of thin hot mixture asphalt. The results show that the thin hot mixture asphalt has performed slightly different on the Marshall and structural properties compare to conventional asphalt concrete.

Abstract: The mechanical strength of hydraulic binder made by blending type I Portland cement (PC) and pozzolan has been examined at the age of 3, 7, 14, 28 and 90 days.The mechanical strength test was realized by using mortar specimens measuring 40x40x160 mm according to NF EN 196-1. The mix proportion of mortarwas 0.5 water :1.0 hydraulic binder : 3.0 sand, by weight.The hydraulic binder was a mixture of 80% PC and 20% pozzolan. Five types of pozzolan were used in this study: two natural pozzolan and three artificial pozzolan. As a control, it was made a mortar havingthe same proportion except that the hydraulic binder was 100% PC. The test result showsthat all of pozzolan present a good pozzolanic reactivity. At 3 days,the strength of the mortar with blended binder (MBB) is lower than the strength of the control mortar (CTM). At that time, the flexural tensile strength and the compressive strength of the MBB rangerespectively from 5.23 to 6.81 MPa and from 13.61 to 18.37 MPa, whereas the CTM strength has reached 7.30 MPa and 27.92 MPa. The MBB strength increasesand it canachieve or even exceed the CTM strengthwith increasing age of hydration. In fact, at 90 days, the flexural tensile strength and the compressive strength ofMBB can reach about 10.08 to 11.06 MPa and 49.69 to 54.17 MPa respectively. In this period of hydration, the flexural tensile strength and the compressive strength of CTM are only 10.13 MPa and 49.00 MPa. The different development of the mechanical strength of MBB could be stronglyrelated to the chemical content of the pozzolan used, especially, reactive silica and reactive alumina.

Abstract: The failure of retaining wall construction can be occurred due to the forces acting on the rear wall exceed the capacity of its stability. Dynamic acceleration parameters can affect the movement pattern of granular soil behind the retaining wall. This research aims to study the movement of grain behind the retaining wall by laboratory testing. The retaining wall model was made in the glass box of a length of 2 meters, width of 0.4 meter and height of 1 meter. This models used gravity types, which was made of concrete and was placed on dry sand with a trapezoid-shaped a height of 20 centimeters, width of peak 2 centimeters and width of below 10 centimeters. The model was examined using dry sand material with grain size that can pass through sieve No. 4 and retained on sieve No.100 of loose sand density (γd = 1.4184 gr/cm³). The model was vibrated using shaking tables with a given variation on sinusoidal loads and was recorded using accellerometer. The displacement of granular soil in a particular point was also monitored during vibration. The results shows that there is different grain movements resulted from different acceleration. The increase in vibration accelerates the grain to fill the empty space between the grains. This causes wider movement area of the grain and expands the landslide areas.

Abstract: Deformability of concrete decreases as its strength increases. The higher the concrete strength, the lower it’s failure strain which shows increase of brittleness. One way to improve the ductility and carrying capacity of concrete is by doing confinement of the concrete. A steel ring external confinement was used in this study. The steel ring is made of a steel cylindrical tube that is cut with a specific width (a) so similar to the ring. The steel ring is placed at a specific distance between the ring (b). With ring width variation (a = 28, 45 and 73 mm) and the distance between the steel ring is constant (b = 40 mm), gave the variation of the volumetric ratio which will afffect the confinement on the concrete. The test results showed that the steel ring was effective as external confinement of the concrete. The capability of concrete to support load increases in line with the width of the ring. Increased carrying capacity of concrete for 28, 45 and 73 mm ring width is respectively 115.382%, 131.792%, 150.253% and the maximum strain of concrete increases to 389.474%, 368.421% and 366.667%, respectively.

Abstract: A large amount of waste concrete generates an environmental problem due to demolition of old concrete structures. To solve this problem, it is necessary to collect recycled aggregate from waste concrete. The conventional recycling technique of recycled aggregate from waste concrete does not indicate a significant quality to be re-used for making a new concrete. We proposed new techniques to produce high grade recycled aggregate by heating-grinding (H-G) method and heating-grinding-acid (H-G-A) method. To ensure the quality of the concrete made from recycled coarse aggregate concrete, the non-destructive evaluation was conducted in this research. High grade recycled aggregate concrete were prepared in advanced using two methods mentioned earlier. Then, new concrete specimens were produced using those types of recycled aggregate concrete. After 28 days curing time, rebound hammer test and ultrasonic pulse velocity test were performed on recycled coarse aggregate concrete to examine the surface hardness and ultrasonic wave velocity of the concrete. Almost similar quality to natural coarse aggregate in terms of density, water absorption, sieve analysis achieved by both H-G recycled coarse aggregate and H-G-A recycled coarse aggregate. However, the surface hardness and ultrasonic wave velocity of H-G-A recycled coarse aggregate concrete is better than those of H-G recycled coarse aggregate concrete. That acid solvent enables to dismantle the cement paste from aggregate surface more effectively, so this types of recycled aggregate shows a better performance than the other one. Continued delamination reduces pores in the interfacial transition zone resulting better bonding mechanism between new cement paste and recycled aggregate surface.