This research concerns the using fresh natural rubber (NR) for development of concrete works. The purposes of this research were to study the finding method for mixing them together with consideration of workability and strength properties. The proportion of concrete itself was 1:2:4 for cement: sand: aggregate by weight. Then, the proportion of concrete with polymer cement ratio (P/C) was mixed at 0.05, 0.10, 0.15, 0.20 and 0.25 respectively. After, the mixed concrete was tested the slump test and cast them in standard moulds (Cubic = 15×15×15 cm and Beam = 15×15×75 cm). Finally, the hardened concrete was tested to determine the compressive and flexural strength properties. The strength test was done after moist cured 7 days and dry cured at 3, 7, 14, and 28 days respectively. The research found that concrete must be added with 4 % nonionic surfactants by cement weight. Lutensol XL 80 (C10 – Guerbet Alcohol Alkoxylate) was selected. And liquid ammonia (NH3) was mixed in NR that was not decrease concrete strength. All NR concrete was collapse slump. While, the normal concrete was 7 cm true slump. For compressive strength, NR concrete decreased by 60 % approximately. Also, the more P/C was added, the strength trended to decrease. However, the failure of NR concrete with high P/C was constrained by white micro fibers. For flexural strength, it decreased by 10 % approximately with increase of P/C ratio. However, after concrete was cured for 14 and 28 days at P/C = 0.15 and 0.20, the flexural strength was higher than normal concrete because polymer particles were attached by tight film. In Conclusion, the using was recommended W/C = 0.4 and P/C = 0.15 which gave > 45 ksc of compressive strength and > 30 ksc of flexural strength after dry cured 14 days or more. Example of mixed proportion of 1 m3 of NR concrete was 343: 686: 1,371: 60: 14: 129 for cement: sand: aggregate: water: nonionic surfactants: fresh natural rubber (%TSC 40) by weight. Therefore, it is not suitable for compressive structures but maybe suitable for repairable works because the capacity of NR constrained to hardened concrete by micro fibers. However, many problems occurred such as air entrained and delay of setting time. Those need to be studied more for improvement.