Sound absorbing materials made by embedding crumb rubber waste in a concrete matrix

•Sound absorbing concrete composites with embedded crumb rubber were made.•Various analysis techniques helped to identify the best mixture.•Sound absorbing coefficient α was higher than 0.5 for 9 of 12 samples.•α reached top values of 0.82 and 0.93 when favorable conditions existed.•SOM and PCA techniques were used to identify correlations and similarities. The aim of this study is to characterize the acoustical behavior of concrete made with crumb rubber waste from sport fields. Concrete mixes with different water to cement ratio (0.45, 0.50 and 0.55) and crumb rubber dosages (0%, 5.0% and 7.5% by weight) were prepared. Properties examined for the nine mixes included compressive strength, apparent density, apparent porosity and acoustic tests. Four additional samples with a modeled intrinsic porosity were subjected to acoustic tests in the frequency range 200–3000Hz. Some samples with high crumb rubber dosage were selected to study the interaction between crumb rubber wastes and cement matrix. Self-organizing maps (SOM) and Principal Component Analysis (PCA) methods were implemented to generate visual clustering and to find out the correlations between experimental data.