Retrofitting of concrete for rigid pavement using bacterial: A meta-analysis

Cracking in tension causes damage to regular concrete. When the surface of the concrete cracks, liquids can enter and damage the structure. Remediating concrete in rigid pavements is time-consuming, costly, and challenging. Concrete cracking can be reduced using sustainable solutions, such as concrete bacteria. Using concrete bacteria is an innovative method for continuously retrofitting concrete, improving its durability, and reducing maintenance costs. Several studies have explored the possibilities of a wide range of bacteria and demonstrated concrete retrofitting. However, in these extensive studies of sustainable solutions, the role of concrete bacteria in retrofitting concrete for rigid pavement has not been clarified. This meta-analysis aims to compare and contrast the performance of various microorganisms in concrete restoration, considering the bacteria concentration, total concrete components, and water/cement ratio. Data from 371 articles were entered into the initial database and 37 articles into the final database for meta-analysis. Low concentrations (10 CFU/mL) of Bacillus subtilis increased the compressive strength after 28 days at 46.8 MPa, and the optimum concentration of Bacillus subtilis was 105 CFU/mL, resulting in an optimum compressive strength of 58.2 MPa after 28 days, an optimum water/cement ratio of 0.3, and the optimum total ingredients (cement, fine and coarse aggregates) ranging from 2000 to 2400 kg/m3. This meta-analysis study supports a new approach to selecting concrete bacteria and developing sustainable advances in concrete technology.

Social-life cycle assessment of oil palm plantation smallholders in Bengkulu province, Indonesia

Smallholders are often seen as a weak point in the development of oil palm plantation production. The quality and yield of their production are considered low according to world market standards; the continuity of their production is irregular; and finally, improving the welfare of farmers is difficult to achieve. However, smallholder plantations have an important and strategic role in achieving sustainable development. This study aims to assess the social life cycle assessment of smallholder oil palm plantations in Bengkulu Province by involving stakeholders consisting of workers, local communities, farm owners, and value chain actors. A total of 600 respondents were selected using quota sampling and interviewed using a structured questionnaire. Data analysis was conducted using social-life cycle assessment, involving various social issues and relevant social indicators for each stakeholder. The findings in our research show that smallholder oil palm plantations still do not meet the minimum wage for workers, and the equipment used by workers is still very minimal in terms of security and safety guarantees. The price of palm oil continues to fluctuate, and plantation policies are constantly changing, making it difficult for oil palm owners to meet the standards and various rules that are set for managing oil palm plantations. In addition, oil palm plantations are no longer a guarantee for the fulfillment of food security conditions for household owners, workers, communities, and actors involved in the oil palm institutional chain. Our finding is that, surprisingly, there is a low level of commitment by smallholders and the government to sustainability in oil palm plantations. The Indonesian Sustainable Palm Oil and Roundtable on Sustainable Palm Oil as standards for sustainable oil palm plantations, as well as global standards for oil palm plantations to demonstrate environmentally friendly production processes, have not been able to compel smallholders to implement sustainable development in oil palm. Various policies formulated by the Indonesian government are perceived to have not addressed the core issues faced by small-scale farmers. Policies supporting small-scale farmers, particularly those related to increasing productivity, fostering and monitoring the environmental management of palm oil plantation activities, and ensuring ownership of plantation, are necessary for the achievement of sustainable smallholder palm oil plantation development.