Abrasive water jet machining of fly ash and metakaolin based geo-polymers Marimuthu Uthayakumar, Ponnambalam Balamurugan, Kinga Korniejenko, Szymon Gądek and Dariusz Mierzwiński MATEC Web Conf., 322 (2020) 01020 Published online: 14 October 2020 DOI: 10.1051/matecconf/202032201020