Evaluation of unit weight and compressive strength of geopolymer mortars obtained with press filter waste and fly ash under different conditions

Abstract

In sugar production industry, the lime obtained from the commercially available limestone is quenched, filtered and used in the production of juice. The excess lime added to the juice is removed from the juice in the carbonation boilers with the help of CO2. The mud part of the remaining muddy juice was precipitated in decanters; filtered with the help of filters. This waste from the filters is called as “Press Filter Waste (PFA)”. In the experimental study, mortar samples were obtained by using standard sand, water, sodium silicate (Na2SiO3), fly ash and PFA in accordance with the literature review performed as preliminary examination. Fresh and hardened mortar properties were evaluated by applying unit weight and compressive strength tests depending on different sieve, curing conditions and water content variables on these mortar samples. Mortar mixtures were prepared with a sand/binder ratio of 3.0. When the compressive strength of PFA10T2S2E1 type samples which are activated with the help of 220 ml alkaline activator and have 75 gr water content and fly ash content passed through 75 µm sieve are evaluated; it has been determined that the compressive strength of 7-day is 18.53 MPa, 28-day is 19.58 MPa and 56-day is 19.78 MPa. When the hardened unit weight of the samples were evaluated (28th day), it was determined that the PFA10T2S2E1 type samples having the highest hardened unit weight were activated with 220 ml Na2 SiO3 alkali activator and the fly ash was passed through 75 µm sieve and the water content was 75 gr (1.934 kg/dm3).