Nanostructured Clay (NC) and the Stabilization of Lateritic Soil for Construction Purposes

The use of Nanostructured Clay additive in lateritic soil stabilization and their effect at different percentages on the natural soil was investigated. The preliminary tests on the soil showed it was an A-2-7 soil, according to AASHTO classification. The soil sample was also observed to be silty clayey sand and the general rating as a sub-grade material was ‘GOOD’. The consistency limits result shows that the value of the LL for the natural soil is 47% and 25.15% was recorded for the plastic limit (PL) and finally the PI was 21.85% i.e. highly plastic soil. Further, the effect of the addition of NC in the proportions of 3%, 6%, 9%, 12% and 15% by weight of the stabilized Umuntu Olokoro lateritic soil was investigated. The consistency limits results showed that the addition of variable proportions of NC considerably improved the plasticity of the stabilized soil which gave 13.8%; a medium plastic material at 15% NC addition, compared to the preliminary result of 0% by weight additive which gave 21.85%; a highly plastic material. The strength properties’ test showed significant improvements with the addition of NC; CBR test result recorded 29% at 15% by weight proportion of NC which satisfies the material condition for use as sub-base material and the UCS test results similarly improved consistently and recorded a maximum UCS of 340.18kN/m2 at 15% by weight proportion of NC addition which satisfies “very stiff” material consistency for use as sub-base material. With the foregoing, the addition of various proportions of NC to the stabilized lateritic soil has presented to be a Geotechnical solution to the varied environmental failures on the road pavements. Hence NC satisfies all the material conditions for use as a sub-base material for the stabilization and improvement of the strength characteristics of lateritic soils. Finally, we call on the relevant agencies to use NC as an additive in stabilizing weak lateritic soils for use as either sub-grade or sub-base materials to save both cost and the structural failures on the roads in south eastern Nigeria. Keywords: Environmental Geotechnics; Pavement Geotechnics; Soil Stabilization; Weak Lateritic Soil; South Eastern Nigeria

Hearing loss prevalence and years lived with disability, 1990–2019: findings from the Global Burden of Disease Study 2019

Background Hearing loss affects access to spoken language, which can affect cognition and development, and can negatively affect social wellbeing. We present updated estimates from the Global Burden of Disease (GBD) study on the prevalence of hearing loss in 2019, as well as the condition's associated disability. Methods We did systematic reviews of population-representative surveys on hearing loss prevalence from 1990 to 2019. We fitted nested meta-regression models for severity-specific prevalence, accounting for hearing aid coverage, cause, and the presence of tinnitus. We also forecasted the prevalence of hearing loss until 2050. Findings An estimated 1·57 billion (95% uncertainty interval 1·51–1·64) people globally had hearing loss in 2019, accounting for one in five people (20·3% [19·5–21·1]). Of these, 403·3 million (357·3–449·5) people had hearing loss that was moderate or higher in severity after adjusting for hearing aid use, and 430·4 million (381·7–479·6) without adjustment. The largest number of people with moderate-to-complete hearing loss resided in the Western Pacific region (127·1 million people [112·3–142·6]). Of all people with a hearing impairment, 62·1% (60·2–63·9) were older than 50 years. The Healthcare Access and Quality (HAQ) Index explained 65·8% of the variation in national age-standardised rates of years lived with disability, because countries with a low HAQ Index had higher rates of years lived with disability. By 2050, a projected 2·45 billion (2·35–2·56) people will have hearing loss, a 56·1% (47·3–65·2) increase from 2019, despite stable age-standardised prevalence. Interpretation As populations age, the number of people with hearing loss will increase. Interventions such as childhood screening, hearing aids, effective management of otitis media and meningitis, and cochlear implants have the potential to ameliorate this burden. Because the burden of moderate-to-complete hearing loss is concentrated in countries with low health-care quality and access, stronger health-care provision mechanisms are needed to reduce the burden of unaddressed hearing loss in these settings