Department of Civil Engineering

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Subject: search.filters.subject.Microsurfacing mix

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    Laboratory Investigation on the Effect of Emulsion Type and Additive on Microsurfacing Mix
    (ASME, 2019-10) Bhargava, Nishant
    In this article, the effect of emulsion type and additive on the performance of microsurfacing mix is evaluated both for initial mix characteristics and long-term performance. Three mix formulations were used for microsurfacing performance assessment, including cationic slow set (CSS) 1-h, cationic quick set (CQS) 1-h Mix 1 with additive, and CQS 1-h Mix 2 without additive. Here, the additive used primarily imparts rapid setting and acts as an adhesion promoter. Also, for each formulation, microsurfacing performance was assessed at 4 emulsion contents. The initial properties were evaluated in terms of workability, set and cure time of the mix, and filler–emulsion compatibility. On the other hand, long-term performance of the mix was assessed in terms of resistance to raveling and rutting. It was found that the emulsion type had a major effect on cohesion development where the mix with CSS 1-h emulsion had relatively lower cohesion than CQS 1-h Mix 1. The abrasion loss and sand adhesion were also affected by emulsion type, which could probably be attributed to better compatibility of CQS 1-h emulsion with the aggregates used in this study. It was also interesting to note that although the performance of CQS 1-h Mix 1 was acceptable, the addition of additive resulted in substantial improvement of both workability and performance. The filler–emulsion compatibility increased from 4 to 12 points with the use of additive. The abrasion loss was reduced by 262 to 663 % depending on the emulsion content. Statistical analysis at the 5 % significance level also showed that both emulsion type and additive had a significant influence on microsurfacing performance in terms of mixing time, consistency, cohesion, raveling, and rutting resistance. However, the resistance to moisture damage provided by additive resulted in insignificant differences between CSS 1-h and CQS 1-h Mix 1.
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    Reliability of Microsurfacing Mix Subjected to Variation in Aggregate Gradation
    (Sage, 2020-09) Bhargava, Nishant
    Reliability analysis describes the probability of the pavement satisfying the performance criteria throughout its design life. Assigning reliability during the design stage is vital for the proper planning of maintenance and rehabilitation activities. In this respect, this study evaluates the reliability of microsurfacing mix subjected to variations in aggregate gradation. A total of 10 different combinations of aggregate gradation were selected where the initial five combinations were based on the specification limits and the other five were randomly generated using Monte Carlo simulation. The performance was assessed in relation to cohesion, abrasion loss, rutting, and bleeding. Results indicated a significant variation in test results even when the aggregate gradation was varied within tolerance limits. The primary factors contributing to the variability were the total surface area of aggregates and the mineral filler content in the mix. Reliability analysis of the test parameters was conducted through the specified limits of each test. It was found that the reliability of each test parameter was more than 90%. However, the overall reliability, including all the test parameters, was 73%. The reliability of the microsurfacing mix meeting all the performance requirements increased to 90% when the aggregate gradation tending to a lower specification limit was excluded. Further, the individual reliability of each test parameter was more than 95%. Thus, to ensure higher reliability, microsurfacing mix with a lower total surface area and a lower mineral filler content should be avoided during the production stage of microsurfacing mix.
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    Relative Contribution of Process Control Parameters on the Raveling Resistance of Microsurfacing Mix
    (Sage, 2021-09) Bhargava, Nishant
    Raveling is one of the key performance parameters of microsurfacing treatment. During the material handling and mix production, process control parameters including aggregate gradation, emulsion content, and water content vary inevitably and might increase the risk of raveling. The objective of this study was to quantify the relative contribution of these process control parameters on the raveling resistance of the microsurfacing mix. For this purpose, a total of 30 combinations of aggregate gradation, emulsion content, and water content were subjected to raveling using wet track abrasion test. The investigations showed that the raveling increased for coarser gradation and lower emulsion content, whereas the variation in raveling was minimal with water content. Further, the test results were modeled using an artificial neural network (ANN). The ANN model was able to capture the influence of process control parameters on the raveling resistance of the microsurfacing mix. Garson’s algorithm was used to quantify the relative contribution of each process control parameter on raveling. It was found that the relative contributions of aggregate gradation, emulsion content, and water content were 40%, 28%, and 32%, respectively. Because of their substantial contribution, it is critical to ensure proper quality control of process control parameters during material handling and production of microsurfacing mix. In particular, coarser aggregate gradation in conjunction with lower emulsion content should be avoided to minimize the risk of raveling.
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    Effect of Cement and Fly Ash Dosages on the Characteristics and Performance of Microsurfacing Mix
    (ASCE, 2021-11) Bhargava, Nishant
    In this study, the role of mineral fillers on the microsurfacing mix characteristics and performance was assessed for 10 different combinations of mineral filler type (cement and fly ash) and dosages (0%–3%). The mixes were initially characterized in terms of compatibility, cohesion, and adhesion using Schulze-Breuer and Ruck test, cohesion test, and boiling water test, respectively. Subsequently, the performance of microsurfacing mixes, that is, raveling and rutting resistance, was determined using wet track abrasion test and loaded wheel test, respectively. Results indicated that the filler–emulsion system’s compatibility improved significantly with the addition of cement at the proper dosage. In contrast, mixes with only fly ash as mineral filler had inferior filler–emulsion compatibility. Also, the rate of strength development and adhesion was higher with cement than fly ash. The performance, that is, raveling and rutting resistance, positively correlates with the 60-min cohesion, adhesion, and compatibility (abrasion loss). Interestingly, the combination with 2% cement and 1% fly ash as mineral filler had the best mix characteristic and performance, indicating that the careful selection of the type and the dosage of mineral filler could maximize the durability of the microsurfacing mix.
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    Modeling the Factors Influencing the Rutting and Bleeding Characteristics of Microsurfacing Mix
    (ASCE, 2022-01) Bhargava, Nishant
    In this study, the effect of process control parameters, including aggregate gradation, emulsion content, and water content, on the rutting and bleeding characteristics of the microsurfacing mix was determined. A total of 30 combinations were selected to account for the synergistic variation of process control parameters in the field. Rutting and bleeding were assessed using a loaded wheel test and sand adhesion test, respectively. Laboratory investigations results showed that rutting was predominantly influenced by the combination of aggregate gradation and emulsion content. On the other hand, the combination of coarser gradation, higher emulsion content, and relatively lower water content led to increased risk of bleeding. Multigene symbolic genetic programming was used to model the rutting and bleeding behavior to better understand the complex behavior. The developed model was able to capture the behavior of the microsurfacing mix. A sensitivity analysis was conducted on the developed model by varying the values of input parameters one-by-one from 0.85 to 1.15 at an increment of 0.005. The results showed that the lateral displacement increased up to 1.6, 1.5, and 1.2 times the control mix for coarser aggregate gradation, higher emulsion content, and higher water content, respectively. Moreover, at the optimal emulsion content value, the lateral displacement was minimal. Sand adhesion increased up to 1.4, 1.2, and 1.1 times the control mix for coarser aggregate gradation, higher emulsion content, and lower water content, respectively. Hence, this study outcome identifies the aggregate gradation tending toward the coarser side, higher emulsion content, and variation of water content, either the dry or wet side, during production lead to poor rutting or bleeding performance of the microsurfacing mix
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    Effect of Process Control Parameters on the Workability and Strength Characteristics of Microsurfacing Mix
    (Sage, 2022) Bhargava, Nishant
    This study investigates the effect of production process variation on the workability and strength evolution of microsurfacing mix. Overall, 35 different mixes were produced by varying aggregate gradation, emulsion content, and water content, within the allowable limits. Results showed that when aggregate gradation was coarser, and emulsion and water content higher than the optimum, the mix failed to meet the workability criteria. However, the variation of process control parameters within the allowable limits had minimal effect on strength (cohesion). It was interesting to note that the mix failed to meet the workability limits when the water content was 1% lower than the optimum, or emulsion content was at the lower limit with finer gradation, or both. Regression models were, therefore, developed to understand the individual and interaction effect of process control parameters. Sensitivity analysis of model parameters showed that emulsion and water content predominantly influenced workability, whereas aggregate gradation had the highest impact on strength. In particular, the mix would tend to prematurely break when the total surface area (TSA) increased to 1.1 times the optimum, and emulsion and water content reduced to 0.9 times the optimum. Alternatively, if TSA is 0.9 times and emulsion and water content is 1.1 times the optimum, the mix would be too workable and could potentially lead to segregation. Findings suggested that limiting the variation of water content within ±1% of the optimum ensures acceptable workability. Further, mix with finer gradation and emulsion content on the lower limit should be avoided during production.