Deterministic and simulation modeling of the production of ready mix concrete batch plant industry in Nahr el Maout, Lebanon

Abstract

The Ready Mix Concrete (RMC) batch plant is an industrialized plant, where concrete is mixed from cement, coarse and fine aggregates, water and admixtures. Then, it is delivered to the construction site using a transit truck mixer. Calculating the productivity of RMC batch plants in the combined operation of concrete mixing in the plant and the delivery to the site is a complex task. RMC batch plants researchers or managers try to limit the production evaluation to that of the mixer alone. This approach fails to look at the batch plant production as a whole system, thus it fails to assess the bottle necks, querying and idleness in each part of the plant system. This paper analyzes the production of the RMC batch plant mixing and its delivery to the site. The productivity is evaluated using two approaches: a deterministic and a stochastic. The deterministic approach develops a general production model and assesses a deterministic productivity. On the other hand, a stochastic approach to productivity evaluation uses probabilistic activity durations and assesses a probabilistic productivity. The simulation model is based on the Monte Carlo simulation technique applied to MicroCyclone web-based software. Both, the deterministic and stochastic models are applied to the HOLCIM plant in Nahr El Maout, Lebanon. The deterministic model found the batch plant production to be 63 m3/hr, while the truck mixers vary between 6 and 36 m3/hr. depending on the truck cycle time and the number of the trucks. The stochastic model simulated the batch plant process with truck delivery to site for 30 iterations, and utilized probabilistic activity durations. It was found that when a steady state is reached it results to a productivity of 55 m3/hr. The simulation model identified that the aggregates, cement and admixture transfer to the central mixer are 95% idle. This research paper is relevant to both the academic field and the industry.