Bituminous Surface Treatment consists of one or more applications of bituminous material and cover aggregate to a primed non-bituminous surface or previously created bituminous surface. The proper application of this surface treatment can lead to the best performance outcome. Materials Bituminous Substances Construction-compliant bituminous material must be RC 800 or RC 3000 cut-back bitumen, quick-setting emulsion, or 80/100 penetration grade bitumen. Additive for Asphalt The bituminous material shall be treated with an Adhesion and Anti-stripping Agent as specified or as required by the Engineer. The additive must be of a type approved by the Engineer, and the needed proportion must be thoroughly mixed with the bituminous material in accordance with the manufacturer's instructions, or as advised by the Engineer, for the period required to form a homogeneous mixture. 
Aggregates Aggregates must be clean, firm, dry, and sound crushed stone or gravel of uniform quality, free of dust, clay, dirt, and other dangerous contaminants, and devoid of an excessive amount of flat or laminated fragments. At least 90% of the particles trapped on a 5 mm screen must have a fractured face when using crushed gravel. The aggregate must be of such a nature that, when adequately coated with the bituminous material designated for the project, the coating is not removed when exposed to water. The aggregate grading must adhere to the building constraints and the appropriate nominal size requirements. 1) For Single Surface Treatment, the nominal size can be set as 20, 14, or 10 mm. 2) The initial course for Double Surface Treatment can be either 20 mm or 14 mm in diameter, followed by a second course with a nominal size of 10 mm. The aggregate must not be sufficiently wet to cause uneven distribution of the pre-coating material, and it must not be used until the moisture has evaporated and the pre-coating material has effectively adhered to the aggregate. 
Pre-Coated Aggregate Aggregates must be pre-coated using an approved pre-coating material to improve bitumen adhesion. Pre-coating material must be applied evenly and thinly to a moving stream of aggregate in an approved mixing plant by means of a fine pressure spray, such that all particles are fully coated but do not contain excess material. The coating must be such that an aggregate particle suspended between the fingers does not exude any substance. Unless the aggregate is suitably covered or the Engineer has authorized the addition of an adhesion agent to the pre-coating mixture, pre-coating of aggregate shall not be undertaken when rain is imminent. Construction Techniques and Equipment The equipment described in this section will be utilized for bituminous surface treatments unless the Engineer accepts alternative construction methods offered by the Contractor. Alternative construction techniques would be particularly effective for tiny areas, walkways, and hard shoulders. The Contractor shall deliver all plant and equipment necessary to do the work in accordance with these parameters, along with the make, model, capacity, weight, and any other specifications the Engineer may request. For seal coats without cover aggregate, the equipment must contain a power brush, a self-powered bituminous material pressure distributor, and, if necessary, heating bituminous material. 
Seal coats with aggregate and surface treatments require a power brush, a drag brush, a bituminous material pressure distributor, a self-propelled pneumatic tire roller, aggregate spreading equipment, a suitable number of vehicles, and, if necessary, equipment for heating bituminous material. Only when authorized by the Engineer may a roller with steel wheels be used. In addition, if coated aggregates, bitumen additives, or rubberized bituminous materials are specified, an application-specific mixing plant must be supplied. Climate Restrictions and Work Management Spraying is forbidden on wet pavement when rain is anticipated or when strong winds are present. The Engineer may temporarily suspend work owing to adverse weather. The Engineer may also suspend construction if he determines that the condition of the materials or other circumstances, such as deteriorating equipment or pavement, would have a negative influence on the project. The contractor will not be permitted to resume work until he has taken the appropriate corrective measures. 
Surface Preparation and Cleaning Before applying bituminous material, the pavement must be cleaned to the satisfaction of the Engineer. Use the power brush to remove loose dirt and other undesirable substances from the surface. If this does not result in a uniformly clean surface, more hand sweeping with hard bass or similar brushes is necessary. At least 200 mm must be swept beyond each edge of the sprayed area when sweeping. Adherent patches of objectionable material shall be scraped from the surface with a steel scraper or other approved means, and the scraped area shall be cleaned as directed by the Engineer with water and hand brushes. If a prime coat has been put to the surface, any area where it has been applied insufficiently or is defective in any way must be re-primed per the Engineer's instructions. Prior to adding any further bituminous material, the primer must be completely dry for a minimum of 48 hours, or longer if necessary. Prior to the use of bituminous material, all necessary preliminary patching of the road surface must be completed to the Engineer's satisfaction. Utilization of Bituminous Product The distributor is responsible for applying bituminous material at the specified or ordered rate and in a uniform manner. The Engineer may authorize the application of hand spray equipment attached to the distributor for small areas. 
The application temperature must fall within the standard range for the bituminous material in question. When an adhesion agent is added to bituminous material, the entire contents of the distributor must be circulated for at least fifteen minutes, or longer if necessary, in order to create a homogeneous mixture at a uniform temperature. It is prohibited to heat excessive quantities of bituminous materials, nor to maintain such materials within the application temperature range for more than ten hours. Any bituminous material that has been overheated or heated for an excessive amount of time must be discarded. In the case of liquid asphalts, the area to be sprayed with bituminous material at any given time shall be limited to that which can be covered with aggregate at the stipulated rate within 15 minutes of the time of spraying, or such a shorter period of time as directed by the Engineer. When so directed, the bituminous material shall be placed in lanes no wider than half the width of the finished surface, with a minimal overlap along the connecting margins of lanes. In the case of successive surface treatments, the bitumen joint on succeeding courses must be approximately 200 mm offset from the joint on the preceding application. for further information on bitumen and bituminous materials, feel free to contact us.
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