Investigating the effectiveness of polypropylene cement bags in reinforcing concrete.

Abstract

There has been use of Polypropylene (PP) for packing cement due high strength and high tear resistance. Due to these excellent properties the present study investigates the effectiveness of PP cement bags in reinforcing of concrete. parameters such as workability, compressive strength, splitting tensile strength and flexural strength were evaluated. Design of experiments using CCD in RSM in the Minitab software was used to obtain the number of runs with varying parameters such as thread length (30mm to 60mm) and thread content (0% to 3%). Concrete with and without PP threads with a characteristic compressive strength of 25 Mpa was designed. Concrete cubes, cylinder and prismatic specimens were cast and tested. The analysis of results (ANOVA) for all properties was used predict the fresh and hardened properties. surface, contour and optimization plots were used to obtain the optimum mix ratio. cost comparison was done based on unit cost method estimation. The Test results indicated the use of PP threads can significantly improve the flexural and splitting tensile strengths of concrete materials whereas it resulted a no significant change in compressive strength. The relative increase in split tensile was optimum at 1.5% dosage of 60mm thread length and flexural strength was optimum at 1.5% dosage of 45mm thread length, though most of the specimens achieved the target strength of 31.56Mpa, decrease in compressive strength was observed and a mild decrease was 20.6% at 3% dosage of 45mm thread length at 28 days .The prediction model established by the RSM showed the correlation and predictability between the response and the factors, and the corresponding relationship equation between the factors and the response was obtained. Results of multi objective optimization indicated that the optimal of the two factors (thread length and thread content) was 1.6% and 56mm respectively with a 0.866 desirability. The use of pp cement bags in reinforcing concrete is economical in terms of cost and eliminates the problem of landfills, reducing the environmental risk, maintaining the ecological balance, which is very much required for our nation. The findings suggested that PP threads deriving from these waste cement bags are a feasible option for fiber-reinforced concrete productions.