Geopolymer

About: Geopolymer is a research topic. Over the lifetime, 6776 publications have been published within this topic receiving 157991 citations. The topic is also known as: geopolymers.

Geopolymer composite for ultra high performance concrete

Abstract: A geopolymer composite ultra high performance concrete (GUHPC), and methods of making the same, are provided herein, the GUHPC comprising: (a) a binder comprising one or more selected from the group consisting of reactive aluminosilicate and reactive alkali-earth aluminosilicate; (b) an alkali activator comprising an aqueous solution of metal hydroxide and metal silicate; and (c) one or more aggregate.

Dilatometry of geopolymers as a means of selecting desirable fly ash sources

Abstract: The use of dilatometry as a screening tool for the analysis of fly ash reactivity in geopolymers is presented and validated by testing six fly ash sources across a range of mix designs. In particular, a prediction of geopolymer mechanical performance can be obtained from the temperature at which the high-temperature expansion peak attributed to the release of strongly chemically-bound water is observed; high-strength samples generally display this expansion at a higher temperature than low-strength samples. Samples made either with a poorly reactive fly ash or an excessive SiO 2 content in the activating solution also expand by up to 10–15% below 200 °C, which indicates a low extent of crosslinking in the silicate gel phase. The second derivative of the dilatometric data can be helpful in identifying the onset temperature of the high-temperature expansion peak, as it is sometimes overlaid on a shrinkage phenomenon attributed to viscous sintering.

Alkali–silica reaction in metakaolin-based geopolymer mortar

Abstract: This paper assesses the behaviour of metakaolin-based geopolymers in the presence of alkali-reactive aggregates. Geopolymer mortars were made with flash metakaolin and sodium waterglass solution in presence of six different aggregates, each having different levels of reactivity to alkali–silica reaction (ASR). The behaviour of geopolymer in presence of such reactive aggregates was investigated by monitoring the dimension changes and the dynamic modulus of the specimens placed in accelerated conditions at 60 °C and 95 % RH for up to 250 days. SEM and EDX analyses were also performed at 170 days to visualize the newly formed products. A comparison with an ordinary Portland cement (OPC) was made for all aggregates in order to evaluate how strongly geopolymers were affected by ASR, if at all. Results showed that geopolymers, although they contained high concentrations of alkalis, were more able to resist ASR than OPC was, and no characteristic swelling or any significant loss of rigidity was observed for the geopolymer specimens. An exception was nevertheless noted for the mortar made with crushed glass sand, where a significant drop in rigidity was found, with the presence of a gel layer at the surface of the glass grains but without any swelling.