The concrete design shall guarantee

The concrete design shall guarantee maximum degree of compaction and maximum workability considering the layout of the baseplates in plain line and S&C, and adequate methods for pouring and vibrating the track concrete.

Concrete work shall be executed under dry conditions. No permission will be give for casting of concrete in ground water. If ground water is encountered, it shall be immediately removed, and the costs for pumping or draining it to an approved discharge shall be borne by the contractor.

Cement shall comply with at leats one of following specifications:
- Vietnamese standard
- Frech standard (definition, classifications, and specifications of cements)
- British standards - BS 12 Portland cements (ordinary and rapid hardening)

The Contractor shall be entirely responsible dor the selection of the type and source of cement suitable for use in the part under construction provided that cement shall be use as indicate in Contract for certain parts or as directed by the Employer.

Aggregates shall be only from natural sources.

The source and type of aggregates shall be carefully selected to satisfy the concrete strength requirements. No aggregates shall be used before conduction of all test required by the relevant specifications or specified in this section.

The coarse aggregate shall be of nominal maximum size 30mm and shall not be more than one fifth of the narrowest dimension between sides of froms, one quarter of the depth of the slabs or three quarter of the minimum clear spacing between bars or bundles of bars or the concrete cover.