The compressive strengths of cement-and lime-stabilised lateritic bricks and blocks were investigated for economical construction in developing countries. Cement-stabilised lateritic blocks and bricks were found to have the best performance and are thus recommended for use.
Ede to Akoda is a trunk B-road built over 30 years ago. It has been in despicable condition leading to fatal accidents and loss of life and properties that impacted negatively on the community. This study investigated the flexible pavement failure along the road in order to ascertain the possible causes of its failure. The methodology adopted covered reconnaissance survey, assessment of the physical condition of the road and soil investigation of subgrade. The result of reconnaissance survey revealed that the surface wearing course has degraded extensively. The physical inspections showed that considerable segment of the drainage facilities has collapsed or totally blocked allowing extensive ponding of rain water on the road surface. The pot holes were deep and widespread in most places and the road is near total collapse. The result of soil investigation revealed that natural moisture content, specific gravity, liquid limit, plastic limit, plastic index, maximum dry density and optimum moisture content were within the specifications of the Federal Ministry of Works and Housing limits (FMWH). However, the California bearing ratio values were less than minimum 10% stated in the specifications, this suggests the nature of subgrade soil as a possible cause of failure of road pavements along Ede-Akoda Road, Nigeria. It is recommended that further research be conducted on other structures of the flexible pavement to better ascertain the causes of the studied road failure.
The wide variety of industrial and domestic applications of plastic products has fuelled a global trend in their use. The vast amount of plastic items that are discarded after use, on the other hand, pollutes the environment. In light of this, the current study investigated the use of Polyethylene Terephthalate (PET) as substitute for natural sand in concrete production. Locally sourced river sand was replaced with industrially ground waste PET in proportions of 4 to 20% at a step of 4% by the weight of natural sand whereas other concrete constituents (cement, granite, water-cement ratio and superplasticizer) were kept constant. A Grade M40 concrete with a mix proportion of 1:1:2:0.35 (cement: sand: granite: water-to-cement ratio) was used for all concrete mixes. Concrete without PET represents the control. Fresh (Slump) and hardened (compressive, split tensile and flexural) properties of the produced concrete were assessed using standard testing methods. The results showed that the slump of concrete decreased by 1.8% and 12.5% with an increase in PET content from 0 to 20%. The 28-day compressive strength of concrete containing PET was lower than the control. However, concrete with 4% PET compared considerably well with control with the compressive strength value exceeding the target strength of 40 N/mm2 while concretes containing PET beyond 4% had compressive strength below the target strength. The split tensile strength of concrete containing 4% PET was higher than that of the control but exhibited lower flexural strength than the control at the age of 28 days. It was concluded that the reuse of PET as a substitute for natural sand as an alternative waste disposal solution for eco-friendly concrete development and attainment of a pollution-free environment is viable.
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