To Whom It May Concern

CONTRACT NRA R.071-030-2020/1MI

MATERIAL INVESTIGATION FOR THE IMPROVEMENT OF NATIONAL ROAD R71 SECTION 3 FROM GRAVELOTTE (KM 0.0) TO NAMAKGALE (KM 44.0) 

You are hereby requested to provide a quotation for an intrusive materials investigation and bitumen stabilisation design on the R71 section 3 that runs from Gravelotte to Namakgale (km 44.00) within the Mopani District Municipality, Limpopo Province. The pricing schedule is attached for your reference.

The majority of the R71 Section 3 is a single undivided carriageway with numerous property accesses. The materials investigation will be conducted at areas with typical base and surface failures on the original road section prior to any inlays or patching.

The investigation will comprise the visual inspection of failed surfaces by saw cutting the multi-surfacing slab. The slab will be extracted intact where possible and inspected for cracks on the cut side. The base surface should also be inspected for rutting and fines and the excavation face for moisture and consistency. The surface of the subbase should be checked for hardness, cracks and signs of stabilisation. The service provider will also be responsible for profiling the test pits, sampling all horizons to a minimum depth of 800mm (existing pavement), reinstating the test pits, transporting the samples to the service provider's laboratory and conducting materials testing.

The service provider is also requested to compile a comprehensive photographic record of the above.

All test pits shall be excavated, profiled and sampled in accordance with the SANRAL M1 Manual and industry best practice. The excavation dimensions shall be sufficient to permit safe working conditions and to allow adequate quantities of material to be sampled from each horizon for the intended testing. 

The test pits must be 1 metre wide by 2 metres long to provide a direct comparison across the wheel track and beyond.

During the test pit excavation and profiling, the presence of an active stabiliser must be confirmed by applying phenolphthalein and hydrochloric acid (HCl) to the sides of the test pits. A change in the colour of the sub-base to purple indicates high alkalinity and a high likelihood of an active stabiliser. Any evidence of effervescence in test pits where HCl was applied suggests that the layer was originally stabilised, but that carbonation has since occurred.

All test pits shall be backfilled with material of equivalent quality to that removed from the relevant horizon. The upper 150mm horizon shall consist of at least G2 quality material stabilised with 2% emulsion and 1% cement. The surfacing shall consist of a 30mm hot/cold asphalt layer. Compaction shall be achieved using appropriate equipment in layers not exceeding 150mm.

Dynamic Cone Penetration (DCP) testing shall be conducted in accordance with the standard test method. Appropriate drilling equipment shall be utilised to penetrate asphalt, highly stabilised or cemented layers prior to proceeding with the testing. The results of DCP testing shall be produced in a format enabling a full assessment of the various pavement layers.

The individual responsible for conducting on-site profiling and sampling must meet the minimum requirements listed below. Supporting documentation must be provided by submitting proof of the individual's qualification and a concise Curriculum Vitae.