Operational Performance And Maintenance Reliability Of Transit Mixers In Delivery Of Ready-Mix Concrete - An Empirical Study

Ready-mix concrete (RMC) has become a fundamental component of modern construction due to its ability to provide consistent quality, improved workability, and efficient large-scale production compared with conventional site-mixed concrete. In RMC systems, concrete is produced in centralized batching plants using automated control systems and transported to construction sites using transit mixer trucks, enabling controlled mix proportions and improved structural performance. The adoption of RMC has increased rapidly worldwide because it reduces labour requirements, improves production efficiency, and minimizes material wastage while supporting faster construction schedules (Chakraborty et al. 2023; Saini et al. 2025). Additionally, the use of computerised batching, precise material proportioning, and mechanized production processes ensures consistent quality and reliability in construction projects (Kaitukov 2023; Ekawati et al. 2024). The increasing demand for infrastructure development has significantly expanded the global RMC industry, leading to improvements in plant automation, transportation logistics, and quality control systems. Studies have shown that the operational efficiency of RMC plants is influenced by factors such as batching accuracy, transportation distance, truck dispatching strategies, and coordination between production and construction sites (Andika et al. 2025; Chaudhary et al. 2025). Efficient transportation and scheduling of transit mixers are particularly critical because concrete is a perishable material whose properties can deteriorate if delivery delays occur beyond the allowable time limits (Ferrari et al. 2025; Dönmez and Öner 2024). Several studies have investigated optimization models and vehicle routing strategies to reduce transportation delays, minimize operational costs, and improve dispatching efficiency of transit mixers (Weerapura et al. 2023; Siu et al. 2022). These approaches include mathematical optimization models, genetic algorithms, and network flow techniques to determine optimal delivery schedules and routes for RMC trucks.

Another major research focus in the RMC industry relates to the operational performance and reliability of mixing equipment. Concrete mixers and transit mixer drums are subjected to complex mechanical loads during mixing operations, which can influence equipment durability and maintenance requirements. Researchers have applied simulation methods such as discrete element modelling (DEM) and Monte Carlo reliability analysis to evaluate load distribution and structural reliability of mixer components under operational conditions (Mungase and Nemade 2025; Nоvitskiy et al. 2023). These studies demonstrate that mixer performance is strongly affected by mixing energy, blade configuration, rotational speed, and material interaction within the mixing chamber. Improving mixer design and maintenance strategies can therefore enhance operational efficiency and reduce equipment failure risks.

Transportation conditions also play a significant role in maintaining the quality and workability of ready-mix concrete. During transit, factors such as travel distance, ambient temperature, mixing speed, and admixture dosage influence the fluidity and slump retention of the concrete mixture. Previous investigations have reported that loss of workability during transportation can lead to improper placement and reduced structural performance (Kresnadi and Prayogo 2021; Akboğa and Baradan 2017). To address these challenges, several studies have examined the use of chemical admixtures, superplasticizers, and retarders to maintain concrete fluidity and workability during extended transportation periods (Bingol and Arditi 2025; Kabus et al. 2018). These technological interventions enable concrete mixtures to retain their desired rheological properties for longer durations, thereby improving placement quality and construction productivity. In addition to operational and material-related considerations, recent studies have also explored the sustainability and environmental aspects of RMC production. The growing scale of concrete production has raised concerns about energy consumption, greenhouse gas emissions, and resource utilization in RMC plants. Researchers have examined strategies such as waste reuse, optimization of plant operations, and improved production management systems to enhance the sustainability of RMC production processes (Kabus et al. 2018; Murthy et al. 2024). Sustainable RMC production requires efficient plant management, reliable supply chains, and effective quality control mechanisms to ensure both environmental and operational performance. Furthermore, improved coordination between plant operations, transportation systems, and construction site activities is essential to reduce operational inefficiencies and material losses.

Despite the substantial body of research on RMC production, equipment design, and transportation optimization, several limitations remain in the existing literature. Most previous studies have focused on theoretical modelling, simulation approaches, or mix design improvements, with comparatively limited empirical investigations of real operational conditions in RMC transportation systems. In particular, the relationship between transportation distance, transit mixer operational patterns, maintenance requirements, downtime, and associated operational costs has received relatively little attention. Moreover, few studies have analysed real-world operational data from RMC transportation systems to understand the practical challenges associated with transit mixer maintenance, delivery efficiency, and equipment reliability in the construction industry. These gaps highlight the need for empirical studies that examine operational data to evaluate the performance and maintenance characteristics of transit mixers in actual construction environments.

In this context, the present study aims to conduct an empirical analysis of ready-mix concrete transportation and transit mixer maintenance in the construction industry. The research focuses on evaluating key operational parameters such as transportation distance, delivery frequency, unloading methods, maintenance costs, downtime, and equipment reliability using statistical analysis techniques. By analysing operational data collected from RMC transportation activities, the study seeks to identify patterns in transit mixer usage, maintenance requirements, and delivery efficiency. The scope of the research is to provide quantitative insights into the operational characteristics of RMC transportation systems and to evaluate the relationship between transportation parameters and maintenance performance of transit mixers. The findings of this study are expected to contribute to improved management strategies for RMC transportation systems by supporting better scheduling practices, preventive maintenance planning, and operational decision-making in the construction industry. Overall, this research provides a practical empirical perspective on transit mixer operations and maintenance in the ready-mix concrete industry, thereby addressing an important gap in existing literature and contributing to improved operational efficiency and reliability in RMC transportation systems.

EXPERIMENTAL METHODOLOGY

The present study adopts an empirical research approach to evaluate the operational performance and maintenance reliability of transit mixers used in ready-mix concrete (RMC) transportation. Operational and maintenance data were collected from 10 RMC plants located across major construction regions of Tamil Nadu, including Chennai, Coimbatore, Madurai, Trichy, Salem, Vellore, Erode, and Tirupur as shown in figure 1.

Figure 1: Study area map

 These locations represent diverse construction environments such as metropolitan urban zones, industrial corridors, and semi-urban development areas.  The dataset collected from these plants includes operational records of transit mixer trips, transportation distance, delivery duration, unloading method, maintenance cost, and breakdown incidents. An overview of the surveyed plants and the corresponding dataset characteristics is presented in Table 1.

Table 1: Example

Table 1. Overview of surveyed RMC plants and operational dataset

A total of 40 transit mixers operating in these plants were monitored over a five-month observation period, generating 4,250 individual trip records representing complete RMC delivery cycles from batching to site unloading and return travel. The collected dataset included key operational parameters such as kilometres travelled per trip, travel time, unloading methods such as manual or pumping, fuel consumption, downtime hours, and number of trips per day, along with maintenance indicators including monthly maintenance cost, breakdown incidents, and vehicle age. These variables were selected because they directly influence transportation efficiency, mechanical wear, and overall fleet reliability. Both primary and secondary data sources were used, including plant operational logs, maintenance registers, and discussions with fleet supervisors and plant managers to validate operational records. Statistical analysis was conducted to evaluate the relationship between transportation variables and maintenance performance. Descriptive statistical methods were used to summarize operational characteristics across plants, while Analysis of Variance (ANOVA) was applied to identify differences in maintenance costs among different plant locations. Reliability indicators such as Mean Time Between Failures (MTBF) were also calculated to assess the mechanical reliability of transit mixers. The integrated analysis enabled the identification of operational inefficiencies and the influence of transportation conditions on maintenance outcomes in RMC logistics.

RESULTS AND DISCUSSIONS

1. Transportation Characteristics of Transit Mixers

The transportation performance of transit mixers represents one of the most critical operational aspects of ready-mix concrete (RMC) logistics because the quality of fresh concrete is strongly influenced by delivery time and travel distance. To evaluate transportation characteristics, operational records obtained from the surveyed RMC plants were analysed, focusing on parameters such as average trip distance, operational duration, and trip frequency. These indicators collectively represent the efficiency of the RMC delivery cycle and the operational load experienced by transit mixer fleets. Descriptive statistical analysis of the collected responses shows that the average transportation distance per delivery trip was approximately 15.12 km, with values ranging between 7 km and 28 km depending on plant location and distribution of construction sites. Similarly, the average operational duration per trip was 3.07 hours, indicating that most deliveries fall within the acceptable workability window for fresh concrete transportation. The results also show that transit mixers perform an average of 4.83 trips per day, reflecting moderate fleet utilization across the studied RMC plants. These operational parameters are summarized in Table 2.

Table 2: Descriptive statistics of key transportation variables

The distribution of transportation distance across delivery trips is illustrated in Figure 2, which shows the frequency distribution of trip distances recorded during the study. The histogram indicates that the majority of RMC deliveries occur within the 10–20 km range, which is consistent with typical batching plant service radii in urban and semi-urban construction environments. Only a small proportion of trips exceeded 25 km, indicating that most RMC plants are strategically located to minimize excessive transportation distance and reduce potential slump loss during delivery. The results highlight that trip distance and operational time are closely related to transportation efficiency and fleet performance. Longer travel distances increase engine operating hours and drum rotation cycles, which in turn contribute to higher fuel consumption and mechanical stress on mixer components. Conversely, shorter trips often increase the number of daily deliveries, thereby raising cumulative operational hours of transit mixers. Both operational scenarios contribute differently to equipment wear and maintenance requirements.

Figure 2. Distribution of transportation distance for RMC delivery trips.

Overall, the transportation characteristics observed in this study indicate that RMC logistics in the selected regions operate within a moderate delivery radius, allowing concrete to be delivered within acceptable time limits while maintaining reasonable fleet utilization. These findings provide a baseline for further analysis of operational efficiency and maintenance performance presented in the subsequent sections.

2. Operational Time and Delivery Cycle Analysis

Trip duration is a critical operational parameter in ready-mix concrete (RMC) transportation because it determines the effective delivery window before fresh concrete begins to lose workability. The operational cycle of a transit mixer typically includes batching, travel to the construction site, waiting time, unloading, and return travel. Therefore, analysing trip duration provides insight into both transportation efficiency and logistical coordination between batching plants and construction sites. The operational records obtained from the surveyed RMC plants indicate that the average delivery cycle duration was approximately 3.07 hours per trip, with recorded values ranging between 1.8 hours and 5.4 hours depending on plant location, traffic conditions, and site operational factors.

Table 3: Operational characteristics of transit mixer delivery cycles

Plants located in metropolitan areas such as Chennai and Coimbatore showed relatively higher operational durations due to traffic congestion and signalized intersections, whereas plants operating in industrial or semi-urban regions exhibited comparatively shorter delivery cycles. The variation in trip duration is summarized in Table 3, which presents the descriptive statistics of operational time parameters. The results indicate moderate variability in operational duration, suggesting that most deliveries occur within an acceptable transportation window for maintaining concrete workability. The relationship between plant location and average operational time is illustrated in Figure 3, which compares the average trip duration across the surveyed RMC plants. The figure shows that plants located in dense urban corridors experience longer delivery cycles due to increased traffic congestion and higher site waiting times, while plants operating in industrial belts demonstrate shorter and more consistent transportation durations.

Figure 3. Average operational time per trip across surveyed RMC plants

The results indicate that operational time is influenced not only by transportation distance but also by site-level factors such as pump availability, labour coordination, and unloading efficiency. Extended waiting periods at construction sites increase engine idle time and contribute to additional fuel consumption and mechanical stress on mixer components. Consequently, improving coordination between batching plants and construction sites could significantly reduce delivery cycle time and enhance overall fleet productivity. Overall, the analysis demonstrates that while most RMC deliveries occur within acceptable operational limits, variations in urban traffic conditions and site readiness can significantly influence delivery efficiency. These findings emphasize the importance of effective dispatch planning and improved site logistics in optimizing transit mixer operations.

3. Influence of Unloading Method on Delivery Efficiency

The method used for unloading ready-mix concrete at construction sites significantly influences the overall delivery cycle and operational efficiency of transit mixer fleets. During the field investigation, two primary unloading approaches were observed: manual chute unloading and pump-assisted unloading. Manual unloading typically involves labourers transferring concrete using wheelbarrows or buckets, whereas pump-assisted unloading utilizes mechanical concrete pumps to transport the material directly to the required location within the structure. These unloading practices differ considerably in terms of time efficiency and operational impact on the transit mixer. Analysis of the collected responses indicates that pump-assisted unloading considerably reduces the time required to complete a delivery cycle compared with manual unloading methods. The average unloading time recorded for pumping operations was approximately 28 minutes, whereas manual unloading required an average of 46 minutes, depending on site organization and labour availability. The descriptive statistics of unloading duration are presented in Table 4.

Table 4: Comparison of unloading duration for different unloading methods

The difference in unloading duration between the two methods is visually illustrated in Figure 4, which compares the distribution of unloading time for manual and pump-assisted operations as shown in Figure 4, manual unloading accounted for approximately 55% of delivery operations, while 45% of deliveries utilized pump-assisted unloading, indicating a balanced use of unloading technologies depending on project scale and site logistics. 

Figure 4 Distribution of unloading methods used in RMC delivery operations

Extended unloading durations increase the idle running time of the transit mixer drum and engine, which may contribute to increased fuel consumption and additional mechanical stress on mixer components. Furthermore, longer unloading periods can reduce the number of trips a mixer can perform within a working day, thereby lowering overall fleet productivity. From an operational perspective, the adoption of pump-assisted unloading systems can therefore significantly enhance delivery efficiency and reduce operational delays in RMC transportation. The results highlight that unloading method is an important determinant of delivery cycle performance in the RMC supply chain. Improved coordination between batching plants and construction sites, along with the wider adoption of pumping equipment for larger construction projects, can substantially improve transportation efficiency and reduce operational downtime.

4. Maintenance Cost and Operational Reliability Analysis

Maintenance cost is a key indicator of the operational efficiency and reliability of transit mixer fleets used in ready-mix concrete transportation. The maintenance expenditure of transit mixers is influenced by multiple factors, including operational intensity, transportation distance, vehicle age, and breakdown frequency. To evaluate maintenance performance, descriptive statistics of key maintenance-related variables were analysed. The statistical summary of maintenance characteristics is presented in Table 5. The results show that the average monthly maintenance cost of transit mixers was approximately ₹27,850, with recorded values ranging between ₹14,000 and ₹46,000. The observed downtime averaged 13.92 hours per month, while the mean number of breakdown incidents was 1.28 per mixer, indicating moderate operational reliability across the surveyed fleets. In addition, the average vehicle age was 6.3 years, suggesting that most mixers were operating in mid-life operational conditions where maintenance requirements typically increase.

Table 5: Maintenance characteristics of transit mixer operations

 To determine whether maintenance cost varies significantly among the surveyed RMC plants, a one-way Analysis of Variance (ANOVA) was conducted. The ANOVA test examines whether the mean maintenance cost differs significantly across plant locations. The results of the analysis are presented in Table 6.

Table 6: ANOVA results for maintenance cost across RMC plants

The obtained p-value (0.505) exceeds the significance threshold of 0.05, indicating that maintenance cost differences between plant locations are not statistically significant. This suggests that geographical location alone does not strongly influence maintenance expenditure. Instead, maintenance cost appears to be more strongly affected by operational conditions such as transportation distance, vehicle usage intensity, and equipment condition. To further examine the relationship between transportation conditions and maintenance expenditure, the association between kilometres travelled per trip and maintenance cost was analysed. The relationship is illustrated in Figure 5, which presents a scatter plot of transportation distance against maintenance cost.

Figure 5. Relationship between transportation distance and maintenance cost of transit mixers

The scatter distribution reveals a strong positive relationship between trip distance and maintenance cost, indicating that mixers operating on longer delivery routes experience higher mechanical wear and repair requirements. Increased travel distance results in longer engine operating hours, higher drum rotation cycles, and greater stress on hydraulic and transmission components. Consequently, optimizing delivery routes and reducing unnecessary travel distances can significantly improve fleet efficiency and reduce maintenance expenditure. Overall, the combined descriptive analysis, ANOVA results, and scatter plot observations indicate that operational intensity and transportation distance play a dominant role in determining maintenance cost, while plant location itself has a relatively limited influence.

5. Reliability Assessment Using Mean Time Between Failures (MTBF)

The reliability of transit mixer fleets is an important factor influencing the continuity and efficiency of ready-mix concrete (RMC) transportation. Mechanical failures can disrupt delivery schedules, increase operational downtime, and lead to higher maintenance expenditure. Therefore, evaluating equipment reliability provides valuable insights into the performance and sustainability of transit mixer operations. In this study, the reliability of transit mixers was assessed using the Mean Time Between Failures (MTBF) metric, which represents the average operational duration between two consecutive equipment failures.

MTBF was estimated by analysing operational hours and recorded breakdown incidents obtained from the surveyed RMC plants. The calculated results indicate that the average MTBF of the observed transit mixer fleets was approximately 121.4 hours, with values ranging between 65 hours and 185 hours, as summarized in Table 7. These results indicate moderate reliability levels across the surveyed fleets and suggest that most transit mixers can operate continuously for several days before the likelihood of failure increases.

Table 7: Reliability indicators of transit mixer operations