The radiation shielding and microstructure properties of quartzic and metakaolin based geopolymer concrete

Today, binders with low CO2 emissions are preferred in building design. Geopolymers have lower CO2 emissions than conventional concrete and Portland cement. This study investigated the efficiency of geopolymers produced with short curing time and low curing temperature against gamma and neutron radiation. Ground blast furnace slag (GBFS), metakaolin and quartz powder were used as binders to produce geopolymers. In addition, 200, 400 and 800 kg/m(3) quartz sand (with high SiO2 content) was used instead of river aggregate in the mixtures. Geopolymers were cured at 40, 60 and 80 ? for 6, 8 and 10 h. The hardened unit weights of geopolymers vary between 2160-2346 kg/m(3). As the quartz sand content increased, the hardened unit weight of the mixtures increased. As the curing temperature increased, the unit weight of the mixtures decreased as the evaporation increased. The compressive strength of geopolymers varies between 40.3 and 153.9 MPa, and the flexural strength varies between 3.3 and 8.8 MPa. As the curing temperature and time increase, the mechanical properties of the mixtures improve as the geopolymerization increases. In addition, if quartz sand is used instead of river sand, the compressive strength can increase up to 40%. With the increase of quartz sand content, the capillarity coefficients of geopolymers decrease. Capillarity coefficients of geopolymer mixtures are below 0.10 kg/m(2).min(0.5). Besides, fast neutron/photon radiation-shielding features of the geopolymers were examined, experimentally. The M3 sample is more accomplished at absorbing gamma photons due to its higher GBFS content. The M1 sample with the highest concentration of quartz sand is the most effective sample at attenuating fast neutrons and has a better ?(R) value to some commonly used neutron attenuators. As a result, it has been shown that geopolymers with a compressive strength of about 160 MPa can be produced after 10 h. This study also revealed that M1 and M3 samples can be put to good use for protection from fast neutron and gamma-ray radiations, respectively, and new geopolymer materials can be designed as shielding materials.