The use of nanolayered silicates has developed rapidly over the last years because of their great potential of improving material properties with only a small amount of filler. To achieve best physical and chemical properties, a very good dispersion of the nanofillers, the correct structure in the polymer matrix and a good bonding at the interface is essential. Previous research showed that with correct process settings as well as parameters thermal expansion can be reduced and alkali resistance can be improved. This study reports the effect of nanolayered silicates on the thermal expansion and alkali resistance of unfilled Polypropylene (PP) and Polyamide (PA) and PP and PA reinforced with 50 % glass fibers with respect to utilization in concrete applications. Thermal expansion and alkali resistance of four different polymers (Rialene P10100ST, Rialene P101SGF50ST, Riamid 15000ST, Riamid 150GF50ST; RIA-Polymers) was tested and compared with their counterparts incorporated with different filling degrees (2, 5, 7 %) of nanolayered silicates (Cloisite 30B produced by Rockwood Additives). Therefore test specimens of the different mixtures were prepared with a HAAKE Rheomix lab mixer followed by a forming process to produce testing plates of 2 mm thickness. Thermal expansion of the Plates was tested with a Mettler Toledo TMA. Alkali resistance was shown by comparison of tensile tests of untreated polymers and polymers inlayed in caustic potash for 28 days. Significant differences in thermal and chemical properties were shown between the different materials and different filling degrees. The coefficient of thermal expansion (CTE) of thermoplastic polymers varies between 30 – 200 x 10-5 mm/mm°C and by the use of nanolayered silicates the CTE was reduced to lower regions. Alkali Resistance of polymers was improved significantly. These results are relevant to evaluate the potential of nanolayered silicates for enhancing thermal and chemical properties of different polymers.