Investigation on the performance of bond strength between pavement layers has gain serious attention from researchers worldwide. Typical methods to prepare the double layered testing specimen at laboratory scale is to follow the Marshall procedure or to perform coring on constructed field scale test lanes. For specimen prepared with Marshall procedure, binder course loose mix is compacted at double faces first prior to the application of wearing course loose mix in the compaction mould and perform the compaction of the loose wearing course later. This paper focused on the specimen prepared using Marshall procedure where the upper wearing course is subjected to single face compaction. The feasibility of single face compaction is investigated and the relevant amount of compaction blows is determined to achieve sufficient thickness and degree of compaction. Aggregate is proportioned to achieve a target thickness of 35, 50 and 65mm, at an allowable limit of ±1 mm. For the tested mix incorporating dense graded, open graded and gap graded mix, each mix managed to achieve the required degree of compaction at satisfactory thickness with respective compaction blows.
Kajian ini telah dijalankan untuk menyiasat kelakuan pasir penyambung turapan blok konkrit saling mengunci pada jarak sambungan dan kecerunan yang berbeza. Model di makmal yang berukuran 1.2×0.6 (m2) telah dibina dan blok konkrit daripada jenis quadpave yang bersaiz 200×100×60 (mm3) telah digunakan sebagai lapisan atas. Jarak sambungan yang digunakan adalah 2, 4 dan 6 mm dengan kecerunannya adalah 0, 5, 10 dan 15%. Uji kaji tarik keluar dijalankan untuk setiap keadaan. Hasil kajian menunjukkan jarak sambungan 2 mm adalah jarak sambungan yang paling sesuai untuk gunakan pada jalan yang bercerun. Semakin besar jarak sambungan, semakin menurun sifat penguncian antara blok konkrit. Ini berlaku di mana daya yang diperlukan untuk menarik blok keluar semakin mengecil apabila jarak sambungan semakin lebar. Kehadiran air dalam kuantiti yang sedikit menyebabkan pasir pengisi menjadi lebih mampat tetapi apabila air terlalu banyak, hakisan akan berlaku. Kajian ini mencadangkan kecerunan maksimum penggunaan turapan blok konkrit saling mengunci adalah sehingga 10% untuk mengelakkan hakisan pasir pada penyambung dan juga penurunan sifat penguncian antara blok konkrit.
Quality of bond between layers of asphaltic concrete course is a key element to ensure the performance of a modern asphalt pavement. A proper interlayer bond ensures the structural integrity of the pavement and prevents possible distresses from occurring within the designed service life. In Malaysia, delamination is a common distress related to insufficient degree of adhesion though slippage failure can be occasionally encountered. Generally, bond development is closely related to the design factors and construction factors. This paper however focused on the construction factors only, hoping to provide some useful information which might be overlooked by the contractors during construction but is of extreme important especially in enhancing the bond development in the asphalt layers. The construction factors in particular interest discussed in this paper include curing time of asphalt emulsion, surface condition of a pavement and technology and quality of workmanship and construction. It is important to note that both design factors and construction factors are inter-related in optimizing the degree of adhesion. Thus, all factors need to be carefully identified and fulfilled in order to maximize the bond strength between pavement surfacing layers for a better quality and longer service life of pavement in Malaysia.
This study focuses on the potential of electric arc furnace (EAF) steel slag and copper mine tailings as asphalt paving materials with respect to issues of volumetric properties and leaching. In this study, four different asphalt mixes were investigated; each contained EAF steel slag and copper mine tailings of various proportions. Apart from the microstructure analysis of the materials, a toxicity characteristics leaching procedure (TCLP) test was conducted on both the mixes and the aggregates. All the mixes were evaluated by the following parameters: Voids in the mineral aggregates (VMA), voids in total mix (VTM), voids filled with asphalt (VFA), Marshall stability and flow and specific gravity. F-test ANNOVA was used to evaluate the degree of significance of the mixes with each of the evaluated standards. It was observed that the mixes containing either EAF steel slag or copper mine tailings or both gave better results than the control mix. In terms of the TCLP test, none of the detected hazardous elements exceeded the standard limits, which indicates the possibility of using them as construction materials.
In order to cope with the ever-increasing traffic loading and to minimise the cost of road construction and maintenance, several road trials of High Modulus Base (HMB) materials containing a 15 penetration bitumen (known as HMB15) have been carried out in the UK since 1990s. It has been showed that, although HMB15 behaved in a similar way to conventional Dense Bitumen Macadam with a cost saving of approximately 25%, its long-term durability (aging and moisture damage) is still a major concern of researchers as considerable deteriorations have been commonly observed during the ongoing investigations on cored samples from the sites (either with or without traffic loading). The aim of this paper was to quantitatively show the relationship between aging properties of HMB15 and its binder film thickness (binder content), so that an optimum binder content could be determined. In order to achieve this, 5 groups of cylindrical HMB15 specimens with different binder contents (3.5%, 4%, 4.5%, 5% and 5.5%) were fabricated and subjected to SHRP long-term oven aging test (at 85oC for 5 days), their mechanical properties both before and after aging simulation were tested using Indirect Tensile Stiffness Modulus (ITSM) tests. In addition, binders were recovered at different aging stages and their rheological characteristics were investigated with Dynamic Shear Rheometer (DSR) tests. Based on these, aging indices of different groups were calculated and their mathematical relationship with binder film thicknesses was regressed. The results show that the aging properties of HMB15 mixtures are significantly affected by their binder film thicknesses. However, regression analysis between aging indices and binder film thicknesses indicates that, as the binder film becomes thicker than 9.5 μm, the change of aging indices with film thicknesses becomes minor and therefore, a film thickness of approximately 9.5 μm was recommended for HMB15 mixtures.
The dynamic shear rheometer (DSR) is one of the most complex and powerful instruments currently used to characterise the linear viscoelastic (LVE) rheological properties of bituminous binders. However, the DSR also has its limitations in that the measured complex modulus data are exposed to errors, known as compliance (testing) errors, particularly at low temperatures and/or high frequencies. This study was conducted to investigate the validity of equations developed by Schröter and associates on complex modulus data collected using the DSR. The equations used were originally developed based on the calibration of the advanced rheometric expanse system (ARES) rheometer. It was found that those equations are able to satisfactorily correct the data on unmodified bitumens and unaged bitumen-filler mastics, including unaged and aged samples. Similar results were also observed for storage and loss moduli master curves. Finally, the 2S2P1D Model was used to calibrate the corrected complex moduli data and it was found that the model satisfactorily simulates the rheological properties of tested samples.
According to the classical theory of viscoelasticity, a linear viscoelastic (LVE) function can be converted into another viscoelastic function even though they emphasize different information. In this study, dynamic tests were conducted on different conventional penetration grade bitumens using a dynamic shear rheometer (DSR) in the LVE region. The results showed that the dynamic data in the frequency domain can be converted into the time domain functions using a numerical technique. This was done with the aid of the non-linear regularization (NLREG) computer program. The NLREG software is a computer program for solving nonlinear ill-posed problem and is based on non-linear Tikhonov regularization method. The use of data interconversion equation is found suitable for converting from the frequency domain into the time domain of conventional penetration grade bitumens.