Microtonalite Stone aggregates from Quarry

Stone aggregates from quarries for making concrete are quite easily available in Kuching. They are either crushed from Igneous rocks Microtonalite, Granite, Basalt, Andesite or from sedimentary rock Limestone. Igneous rock has the best quality while Limestone is moderately good for concrete usage, but not recommended for foundation structures (acidic ground water) and structures which expose to acid such as roof slabs (acid rain).
This photo shows the commonly available Microtonalite stone aggregates from Kuching.

Central and Northern Sarawak regions such as in Sibu, Sarikei, Bintulu and Miri, do not have igneous rock quarry because of the unfavourable Geology. The stone aggregates used are therefore either the river gravels or the metamorphosed/cemented Sandstone and Limestone Quarries, which are of inferior quality compared to igneous rock quarries. Therefore, if good quality stone aggregates are to be used, they have to be bought from Kuching, which are expensive due to distance.
To determine whether the aggregates are of good quality, there are many tests to be done. These include Uni-axial compression tests for parent rocks, Sieve analysis, Crushing Value test, Impact Value test, Los Angeles Abrasion test, 10% fines test, Specific gravity, water adsorption test and sodium sulphate test, just to name a few major ones. In view of the cost and fear of failing, not many quarries or suppliers are willing to do such tests. But the local Authorities require Building structures to comply to the MS/BS standards, Engineers have to check the quality of the stone aggregates before being allowed to use. But how many of them really checked these requirements, especially the Central and Northern Regions where tests are not even available?