Bulletin of the Geological Society of Malaysia, Volume 26, April 1990, pp. 97 – 108
Geological Survey of Malaysia, Ipoh
Abstract: Concrete is known to deteriorate as a result of interaction between certain reactive minerals in some types of aggregates and the alkaline pore fluids originating from Portland cement. This interaction which is known as alkali-silica reaction (ASR), was highlighted in Malaysia in March 1988 when the Singapore Government banned the import of volcanic quarry stones from the Pengerang area in Johor.
Based on rock aggregate tests, the mechanical and physical properties of tuffaceous rocks are within the acceptable limits as recommended by JKR Malaysia for use as constructional aggregates. However, chemical tests on potential alkali-silica reactivity showed that the tuffs from Pengerang contained reactive minerals. X-Ray Diffraction studies showed the possible occurrences of reactive tridymite and cristobalite in some of the samples. Petrographic studies showed that other reactive minerals are chalcedony and strained quartz, and also possibly, the crypto- to microcrystalline quartz which form the groundmass of the tuffs.
However, as for granites, which are innocuous and abundant in Peninsular Malaysia, the problem of alkali-silica reactivity should not be too worrying.
Abstrak: Konkrit telah diketahui boleh menjadi retak akibat tindakbalas antara mineral silika tertentu yang reaktif yang terdapat simen. Tindakbalas ini dikenali sebagai tindakbalas alkali-silika (ASR) yang telah menjadi tumpuan di Malaysia apabila kerajaan Singapura mengharamkan impot aggregat batuan tuff dari kawasan Pengerang di Johor pada bulan Mac 1988.
Berdasarkan dari ujian aggregat batuan, sifat-sifat mekanik dan fizika batuan berkenaan masih dalam lengkungan piawai seperti yang ditetapkan JKR Malaysia untuk aggregat pembinaan. Walau bagaimanapun, ujian kimia untuk potensi tindakbalas alkali-silika (ASR) terhadap batuan tuff dari Pengerang menunjukkan yang batuan berkenaan mengandungi mineral-mineral yang reaktif. Hasil dari analisis belauan sinar-X yang dijalankan, sebahagian dari sampel menunjukkan kemungkinan kehadiran mineral reaktif seperti tridimit. Kajian petrografi menunjukkan kehadiran mineral-mineral reaktif seperti kalsidoni, kuarza yang tericih dan mineral jisim latar yang terdiri dari kripto-ke mikrohablur kuarza.
Oleh kerana batuan granit banyak terdapat di Semenanjung Malaysia, mengelakan dari menggunakan aggregat yang mempunyai ASR bukanlah satu masaalah yang besar.
https://doi.org/10.7186/bgsm26199009
