How Asphalt Mixing Plants Enhance Bidding Competitiveness

1 Introduction
2 Cost and supply considerations
3 Production capacity and programme reliability
4 Batch and continuous asphalt mixing plants
5 Quality control and technical capability
6 Environmental performance
7 Plant ownership, mobility and financial considerations
8 Using asphalt production capacity in tendering
9 Conclusion
10 Related articles on Designing Buildings

[edit] Introduction

Asphalt mixing plants are used to produce asphalt mixtures for road and other paved infrastructure projects. In competitive construction markets, the availability, capacity and location of asphalt production can influence a contractor's cost estimates, construction programme, supply-chain arrangements and ability to demonstrate technical capability. Asphalt is typically produced by heating and drying aggregates and combining them with bituminous binder and, where required, mineral filler or other additives. The resulting mixture is transported to the paving operation and compacted while it remains within the required temperature range.

For contractors bidding for road and bridge projects, control over asphalt production can provide greater certainty over material supply and production capacity. However, owning an asphalt mixing plant does not automatically make a tender more competitive. Its value depends on factors including project size, production requirements, plant location, transport distances, utilisation, capital and operating costs, environmental requirements and the terms of the tender.

[edit] Cost and supply considerations

Accurate assessment of material and logistics costs is an important part of preparing a construction tender. Where asphalt is purchased from a third-party supplier, the contractor may need to account for the supplier's production costs, transport charges, availability and delivery capacity. These factors can be particularly significant on large or remote projects where substantial quantities of asphalt are required.

Operating an asphalt mixing plant can give a contractor greater control over production and procurement. Aggregates, bituminous binder and mineral filler can be procured in quantities appropriate to the project, while production can be coordinated with the paving programme. However, the potential cost advantage must be assessed against the capital cost of the plant, installation, operation, maintenance, fuel, staffing, material storage, testing, transport and environmental compliance.

The location of the plant is also significant. Asphalt is normally transported hot to the paving site, so excessive haul distances can affect temperature, transport costs and the practical rate of supply. A suitably located mobile or temporary plant can reduce haul distances on some projects, although mobilisation, site preparation and subsequent relocation also incur costs. Mobile asphalt plants are available in both batch and continuous configurations.

[edit] Production capacity and programme reliability

The production capacity of an asphalt mixing plant should be matched to the requirements of the paving operation. Insufficient production capacity can constrain paving productivity, while excessive capacity can result in inefficient plant utilisation and unnecessary capital and operating costs. The required capacity depends on factors including the volume and type of asphalt, paving rate, working hours, delivery distance and available storage.

An appropriately planned asphalt production facility can reduce dependence on external suppliers and provide greater control over the timing of material production. This can be particularly useful where the project is remote, where local commercial supply is limited, or where large quantities of asphalt are required over a sustained period.

Programme reliability nevertheless depends on more than plant availability. Aggregate and bitumen supply, plant maintenance, fuel availability, laboratory testing, weather, transport, paving equipment and workforce availability can all affect production and laying operations. An asphalt plant should therefore form part of an integrated production and paving plan rather than being considered in isolation.

[edit] Batch and continuous asphalt mixing plants

Asphalt mixing plants can broadly be divided into batch and continuous types. Batch plants produce asphalt in discrete batches, allowing the composition of individual batches to be adjusted between production cycles. This can provide flexibility where a project requires several mix designs or frequent changes in material specification.

Continuous plants produce asphalt continuously once production has been established. They can be suited to projects requiring high and relatively consistent production rates, particularly where large quantities of a relatively uniform mix are required. The choice between batch and continuous production should be based on the project's required output, mix specifications, production flexibility, capital cost and operating conditions rather than on a general assumption that one type is universally more economical.

[edit] Quality control and technical capability

Asphalt production requires control of aggregate grading, aggregate moisture, binder content, mixing temperature and other characteristics relevant to the specified mixture. Modern plants can incorporate automated weighing, temperature monitoring and control systems to improve consistency and record production data.

A contractor's ability to demonstrate suitable production, testing and quality-control arrangements can contribute to the technical assessment of a tender where the procurement documents require such information. Tender submissions may include details of available plant and labour resources, proposed construction methods, quality-management procedures and previous experience, depending on the procurement requirements.

The presence of an asphalt plant does not, by itself, demonstrate that the required asphalt specification will be achieved. Appropriate mix design, material testing, calibration, plant operation and quality assurance remain necessary. The asphalt produced must comply with the specification applicable to the project.

[edit] Environmental performance

Environmental requirements can affect the selection, operation and economics of an asphalt mixing plant. Important considerations include fuel consumption, energy efficiency, dust emissions, gaseous emissions, noise, material transport and the use of reclaimed asphalt pavement (RAP) where permitted by the project specification.

Plants commonly incorporate dust-collection systems to control particulate emissions from aggregate drying and mixing processes. The applicable emission limits depend on the jurisdiction, plant design, operating conditions and regulatory requirements; therefore, a universal emissions value should not be assumed.

RAP can be incorporated into asphalt mixtures where permitted by the relevant specification and where the plant has suitable systems for handling and heating the reclaimed material. The proportion of RAP that can be used depends on the mixture, material properties, plant configuration, temperature control and applicable requirements. It is therefore not appropriate to assume that a particular percentage reduction in virgin bitumen or other materials will be achieved on every project.

Fuel selection and burner technology can also affect energy consumption and emissions. The available fuels and their environmental implications depend on local infrastructure, regulations, plant design and project requirements.

[edit] Plant ownership, mobility and financial considerations

For contractors undertaking multiple projects, the potential utilisation of an asphalt mixing plant is an important financial consideration. A plant that can be moved between suitable projects may provide greater utilisation over its working life, but relocation requires dismantling, transport, site preparation, reassembly, commissioning and potentially new regulatory approvals.

The financial assessment should therefore consider the complete life-cycle cost of the plant rather than its purchase price alone. Relevant factors include depreciation, finance costs, insurance, maintenance, spare parts, fuel, labour, testing, environmental controls, mobilisation and demobilisation.

Plant ownership can also affect a contractor's balance sheet and borrowing requirements. The presence of equipment assets does not necessarily improve financial strength or tender prospects: lenders and clients may assess liquidity, profitability, liabilities, available resources, financial history and the contractor's ability to complete the proposed works. The financial and technical evaluation criteria for a tender are determined by the client and the procurement process.

[edit] Using asphalt production capacity in tendering

Tender documents may require bidders to demonstrate that they have access to appropriate plant, resources and technical capability. An asphalt mixing plant can form part of this evidence where asphalt production is a significant component of the works. The contractor may be able to demonstrate production capacity, plant availability, quality-control arrangements, proposed logistics and contingency measures.

However, tender evaluation is normally based on the criteria established in the procurement documents. Price may be considered alongside factors such as technical quality, programme, environmental performance, health and safety, resources, experience and risk management. Possession of a particular item of plant does not guarantee a higher technical score unless it directly satisfies an evaluation criterion.

A competitive tender should therefore demonstrate how the proposed asphalt production arrangements support the specific project requirements. This may include evidence of adequate production capacity, appropriate plant location, reliable material supply, quality assurance, environmental controls and realistic cost and programme assumptions.

[edit] Conclusion

An asphalt mixing plant can contribute to tender competitiveness by providing control over asphalt production, material supply and production scheduling. It may reduce dependence on external suppliers and transport over long distances and can provide production capacity suited to major road projects. These potential advantages must be balanced against capital expenditure, operating costs, maintenance, environmental requirements, utilisation and logistical constraints.

The most appropriate plant configuration depends on the characteristics of the project. Batch and continuous plants offer different combinations of production capacity and mix flexibility, while mobile plants can provide advantages where production facilities need to be relocated between projects. Effective use of asphalt production capacity therefore requires integration with procurement, mix design, quality control, transport, paving and project programming.

In competitive tendering, the principal benefit of an asphalt mixing plant is not simply ownership of the equipment but the ability to demonstrate a technically appropriate, costed and reliable method of producing and supplying asphalt that meets the project's specification and programme.