Alkali-Activated Material Based on Red Clay and Silica Gel Waste

Mechanical Properties of Alkali Activated Material Based on Red Clay and Silica Gel Precursor

“…Results of obtained AAM in terms of strength correspond well to previous investigations. Borg et al observed similar tendency as compressive strength decreased from 9 to 1 MPa as thermally treated (600 °C, 900 °C) silica gel addition was incorporated to AAM from 5 to 50 wt.% [9]. 6 M NaOH activation solution in combination with metakaolin obtained at 800 °C allowed to reach AAM with strength from 2 to 4 MPa while the increase of activation solution molarity increased materials compressive strength [29].…”

“…There is a number of researches which focuses on obtaining AAM from different clay types. Up to now, the suitability of other clay based raw materials as precursors for AAM binders, such as mica, smectite or even interstratified illite-smectite has not been well researched [7]- [9]. The Baltic States such as Latvia and Lithuania are rich with red clay deposits and red clay valorization in production as an alternative binder seems to present opportunities.…”

“…Silica gel has high content of SiO2 and therefor might be attractive for use in alkali activation process as silica source. t of produced AlF3 generates about 0.5 t of silica gel and up to now the use of the silica gel is limited due to the presence of fluoride compounds [9]. Fluoride compounds are hazardous because of its toxicity, irritating and health hazard properties.…”

“…In building materials, they may negatively affect material properties as fluoride compounds retard the setting process and decrease the mechanical properties of hardened cement pastes and create aggressive environment for steel rebars [19], [20]. The effort of utilizing silica gel as precursor in AAM has been published by Borg et al, which concluded that 25 % of silica gel add during calcination of clay was an optimal amount [9].…”

Lightweight porous geopolymers from waste red brick precursor and synthetic foaming admixture

“…Construction and demolition waste, as well as secondary by-products from various industries, is also possible to use in the production of geopolymers. There are reports that red brick waste ground to powder particles are suitable for alkali activation, to obtain geopolymer binder with the strength of 30 MPa [12], but there is little effort on the production of lightweight geopolymers based on red clay precursor. In this research development and testing of highly porous red brick powder based geopolymers are examined with different mixture compositions and foaming admixtures.…”