Indirect Tensile Resilient Modulus Tests Research Articles

Stiffness, rutting, and fatigue performance evaluation of cement-natural rubber latex stabilized recycled concrete aggregate

ABSTRACT The stiffness, rutting, and fatigue performance of cement-natural rubber latex (NRL) stabilized recycled concrete aggregate (RCA) were evaluated under cyclic loading. The RCA was stabilized with 3% cement content and dry rubber content to cement (r/c) ratios at 5%, 10% and 15%. The performance evaluation was carried out through advanced experiments, including indirect tensile resilient modulus test, indirect tensile fatigue test, and rutting susceptibility test using a Hamburg wheel tracking device. The results indicated that the r/c ratio of 10% was optimum for cement-NRL stabilized RCA (3C10R-RCA), which exhibited the optimum performance in terms of permanent deformation, fatigue cracking, and rutting susceptibility. The indirect tensile fatigue life of 3C10R-RCA was found to be 79.3% greater than that of the 3% cement stabilized RCA (3C-RCA), while the rut depth of 3C10R-RCA was 8% lower. Although the resilient modulus value of 3C10R-RCA was slightly lower than that of 3C-RCA, the tensile permanent deformation was found to be lower, which is associated with the lower rut depth. As a result of the significant improvement in fatigue life and rutting performance, the resistance to fatigue cracking and premature failure of cement-NRL stabilized RCA were improved.

Investigation of the Usability of Foamed Bituminous Mixtures as Bituminous Base Course

Materials recycled with foam bitumen are promising materials for pavements economically and environmentally. However, there are different opinions in the literature about how these materials are positioned in the pavement. It is clear that their performances will not be suitable for the wearing course, but that they are used for the plant mixture base course because they contain bitumen, and that these materials will be neglected in the evaluation of these materials. In the study, 4 different foam bituminous mixes prepared with a recycled pavement material and a standard bituminous base course mix were compared in terms of the resilient modulus obtained from the uniaxial indirect tensile resilient modulus test. Gradation is the same for three of the mixtures, two of them use cement as a mineral binder, but 70/100 grade bitumen in one of these two productions and 50/70 grade bitumen in the other. In the third mixture, 70/100 grade bitumen and hydrated lime (HL)+fly ash (FA) were used. In the final mixture, 70/100 grade bitumen and cement were used as mineral binders, but gradation was changed. In addition, permanent deformation control for the final production was carried out with a triaxial cyclic compression test. It was concluded that all these variables affect the results, but the resilience modulus values obtained for all were quite close to those obtained from the bituminous base sample. Considering that the foamed bituminous mixtures will be thicker than the bituminous base course in practice, it is considered structurally appropriate to use this layer instead of the bituminous base course.

Evaluation of the double coated recycled concrete aggregates for hot mix asphalt

The use of recycled concrete aggregates (RCAs) in pavement industry can mitigate natural aggregates shortage, promote sustainable practices and reduce construction cost. However, the engineering properties of RCAs are usually inferior to those of natural aggregates. In this investigation, a new state of the art coating technique, namely, double coating technique (DCT), is developed to improve strength and durability of the RCAs. The RCAs were firstly coated with a layer of cement slag paste (CSP) to reinforce its weak particles. Then, a second layer of Sika Tite-BE (here called ABE) was applied to reduce its water/bitumen absorption and enhance the durability. Marshall tests, indirect tensile test, indirect tensile ratio test and indirect tensile resilient modulus test were performed to evaluate intermediate AC14 mixtures made with 0%, 20%, 40% and 60% of double coated recycled concrete aggregates (DCRCAs). The results indicated that the DCT decreases the water absorption of the DCRCAs by 12.3% and 26.1% compared to uncoated RCAs and RCAs coated with CSP respectively. Also, the DCT effectively enhances moisture resistance and produces stiffness higher than 4000 MPa proposed for AC14 intermediate mix according to Australian practices.

Performance evaluation of recycled asphalt mixtures by construction and demolition waste materials

In recent years, Construction and Demolition waste materials (C&D waste materials) have become one of the main environmental and economical concerns to be managed. Using them as aggregate in pavement layers is considered a solution to reduce accumulated building debris in land-fills. In this research, after determining Optimal Binder Content (O.B.C.) of control mixture and those containing 10%, 20%, 30%, and 40% C&D materials, rutting performance of them were evaluated using indirect tensile resilient modulus test, Dynamic Creep test, and Wheel Tracking test. Furthermore, moisture susceptibility were investigated using wet/dry Indirect Tensile Strength (ITS). Using C&D waste materials increases O.B.C. and results of performance tests shows that recycled aggregates improve rutting resistance among which 30% is the most. Moisture damage resistance is also enhanced with C&D waste materials increase.

Evaluation of Warm Mix Asphalt Performance with High RAP Content

The pavement industry is currently forced to find alternative ways to produce asphaltic concrete with the dwindling supply of new resources and the spiraling cost of materials. Warm Mix Asphalt (WMA) using reclaimed asphalt pavement (RAP) offers a sustainable solution to the problem by reducing energy requirements for production and the reuse of old pavement materials. The effects of warm mix asphalt additive (Sasobit) on mixes containing different percentages of RAP were investigated in the laboratory. Three different concentrations of RAP (30%, 40% and 50%) with 1.5% Sasobit by weight of binder were added, and Marshall method was used to produce all samples investigated. Two different mixing and compaction temperatures were used, 155°C and 135°C for mixing and 135°C and 120°C for compaction. The performance of the mixes in terms of stiffness and moisture damage were investigated by carrying out the Indirect Tensile Resilient Modulus Test (ASTM D4123) and moisture susceptibility test (ASTM D 4867). The results obtained showed that there were no substantial differences in volumetric properties, stability and stiffness values of reclaimed mixes than the control mix (conventional hot mix asphalt). In addition, all the mixes investigated achieved the required minimum TSR of 80%. Measured rut depth using the Asphalt Pavement Analyser (APA) device and fatigue cycles to failure using beam specimen indicated that the mixes performed similar to or better than the control mix. The results showed that warm mix asphalt using sasobit-additive and containing high percentages of RAP could be a sustainable alternative to the conventional HMA mix.

Laboratory Test Methods for Foamed Asphalt Mix Resilient Modulus

ABSTRACT This paper investigates laboratory test methods for resilient modulus of foamed asphalt mixes. By comparing test results from different laboratory test methods, the effects of various stress states are identified. The indirect tensile resilient modulus test and the free-free resonant column test were found to yield stress states irrelevant to pavement structures, and to greatly overestimate resilient modulus. Triaxial resilient modulus test results showed that the role of foamed asphalt treatment is to transform the material behavior from that of typical unbound granular materials to that of partially asphalt-bound materials. Flexural beam tests indicated that when subjected to tension, the resilient modulus of soaked foamed asphalt mixes can be very low. Since triaxial and flexural beam tests each characterize one of the two most important stress states relevant to pavement design, test results from these two methods need to be combined to be used in design.

Temperature Effects on Stripping Performance of Superpave Design Mix

Climatic factor such as temperature and moisture has profound effect on the durability of hot mix asphalt pavements. Couple with high traffic loads/stresses made stripping of pavement materials inevitable. Thus, it has become necessary to improve the efficiency of the design of hot mix asphalt (HMA) for better performance and safe riding comfort. This study investigates and discusses the findings on the stripping performance of dense graded Superpave mixes using two types of binder, Penetration Grade (PEN) 80-100 (unmodified) and PEN 80-100 with rubber-polymer (modified binder). The HMA preparation follows the Superpave mix design AASHTO TP4 procedures. The optimum percentage of rubber crumb and Ethylene-Vinyl-Acetate (EVA) polymer was selected based on the previous research. Indirect tensile resilient modulus test was used to evaluate the stripping performance in both unmodified and rubber-polymer modified mixes. This study also documents the effect of different temperatures on tensile strength ratio (TSR) and resilient modulus ratio (RMR) on the HMA mixtures. Statistical analysis performed indicates that rubber-polymer modified binder mix (RPMM) significantly improved the resistance of the HMA mix to moisture damage compared to unmodified mix (UnM).

Laboratory Performance Evaluation of Cement-Stabilized Soil Base Mixtures

In-place cement-stabilized soils have served as the primary base material for the majority of noninterstate flexible pavements in Louisiana for many years. These materials are economically and easily constructed and provide outstanding structural characteristics for flexible pavements. However, these cement-treated materials crack due to shrinkage, with the cracks reflecting from the base to the surface. A laboratory study examined the performance of four different cement-stabilized soil mixtures recently used in the construction of test lanes at the Louisiana Pavement Testing Facilities. Laboratory tests included the indirect tensile strength and strain, unconfined compressive strength, and indirect tensile resilient modulus tests. The four mixtures were ( a) in-place-mixed cement-treated soil with 10 percent cement, ( b) plant-mixed cement-treated soil with 10 percent cement, ( c) plant-mixed cement-treated soil with 4 percent cement, and ( d) plant-mixed cement-treated soil with 4 percent cement and fiber reinforcement. The results indicated that there was no significant difference in performance between the plant-mixed and in-place-mixed cement-treated soil mixtures. The inclusion of fiber to the cement-treated soil mixture significantly increased the indirect tensile strain and the toughness index. Increases in compaction effort maintained or significantly increased the indirect tensile strength and unconfined compressive strength. Increases in curing period maintained or significantly increased indirect tensile and unconfined compressive strength as well as the resilient modulus of the mixtures.