Relative strengths of phosphoric acid-reacted and alkali-reacted metakaolin materials

A study was conducted to investigate the microstructure and cold crushing strength (CCS) of the materials produced by alkaline-bonding and phosphoric acid-bonding of metakolin (MK). The study was conducted to develop these materials, as replacement for some existing uses and for future applications. Metakolin geploymer (MKGP) was prepared by adding MK to the sodium silicate solution. MKGP was made by mixing the deionized water (DIW), with 85 mass% H3PO4 and adding MK to the acid. Minimum amount of water was added, to achieve the required workability, as it was observed that excess water will increase the porosity and decrease strength. CCS specimens, having dimensions of 25 mm in diameter and 40 mm in height were prepared for each batch. The CCS tests were conducted at ambient temperature in a servo-electric universal mechanical testing machine, with a 100-kN load cell.