Comparative Study of Cement Replacement with Waste Plastic in Interlocking Paving Stone for Highway Construction in Nigeria

Portland cement remains the major binder used in the construction of concrete pavements, interlocking stones, and many other aspects of construction, and this implies a high dependence on the commodity thus making it scares and expensive and hence the need to explore other alternatives. This research compares the use of waste plastics and Portland cement for the production of paving stones. In this study, three cases were considered, each case having a study sample and a control sample. Case 1, case 2, and case 3 had mix ratios of (in order of, binder to sand to granite) 1:1:1, 1:1:1.5, and 1:1.5:2.5 respectively, of which the controls were made using Portland cement as the binder and the samples were made with waste plastic as the binder. The comparison was done using compressive strength and water absorption resistance values of the controls and the sample. The results showed that paving stones made from Portland cement have better compressive strength in all cases compared to the samples, the highest compressive strength obtained from the controls was 45N/mm2 while that of the sample was 25N/mm2, however, the study sample showed the highest water absorption resistance percentage of 5%, when compared to the control samples which had as low as 0.8%. This infers that paving stones made from melted waste plastics may not be as strong as those made from Portland cement can be used for roads expected to carry lighter traffic, and are also very suitable for areas of high water table or areas prone to flooding. The samples in this research were made locally and were limited to the three mix ratios mentioned. Further research can be done using a mechanized method to produce the samples, also partial replacement of cement with waste plastic may hence the strength of the paving stone.