CONCRETE PAVING PRODUCTIVITY IMPROVEMENT USING A MULTI-TASK AUTONOMOUS ROBOT
ABSTRACT To improve productivity in conventional concrete construction, autonomous robots that perform specific tasks are being developed. Single-task robots are capable of enhancing specific functions, though their impact on the overall productivity remains unclear. A robot that incorporates each task-specific piece of machinery used in the concrete paving process into one fully autonomous unit is evaluated. Assessing potential productivity from the use of a fully automated process is a required step for developing a full scale-system. With the purpose of identifying productivity benefits in an automated concrete paving operation, two concrete paving processes will be compared using simulation tools. One process is the conventional operation using intensive labour, slip form paving machine and auxiliary equipment. The other process is the automated operation using a fully autonomous robot. Applications of this assessment methodology based in simulation will allow for the determination of productivity indicators of automated operations in hazardous environments, using the respective results to complement prototypical tests.
Fully Autonomous Robot for Paving Operations
Efficiency is low in conventional concrete construction. This fact, combined with high accident rates at construction sites, low product quality, and insufficient controls of the project schedules have led researchers to develop autonomous robots to perform specific tasks. Such robots are highly advantageous for a multi-task operation such as concrete paving. Concrete pavement construction is ideally suited for robotics in that the complete construction process is made up of many single-tasks that can be automated and integrated into a single machine. Although the state-of-the-art paving process includes a high level of automation, the process is still labor intensive and the final quality of the pavement section is a function of the skill of the paving crew. Introducing autonomous robotics into paving operations provides a means to consistently produce high-quality products, faster and safer than conventional concrete paving techniques. Ohio University is developing a 1:20 scale prototype of a fully autonomous robot for concrete paving called RoboPaver. The purpose of the prototype is to serve as a proof-of-concept concrete pavement construction robot. The full-scale version of the RoboPaver will occupy about the same volume as a typical commercially-available slipform paver, but will combine all the operations of a conventional paving system into one robot. The RoboPaver prototype will also implement an intelligent concrete construction system that will allow real-time remote monitoring and control of the paving operations, based on sensors and other machine performance data. The tangible benefits of using RoboPaver for pavement construction will include lower labor costs, lower equipment maintenance costs, less construction downtime, and lower demobilization and cleanup costs. Other potential RoboPaver benefits include increased construction site safety and higher quality of the finished pavement section, both of which can be directly related to a reduction of overall project costs.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.