Experimental study on lightweight concrete using lightweight expanded clay aggregate (leca) and expanded perlite aggregate (epa)

In pursuit of reducing the dead-weight of precast concrete structures, one approach is by adopting lightweight concrete. EN 13369:2013 specifies a minimum cube compressive strength of at least 18 MPa for the lightweight concrete to be eligible for use in reinforced precast concrete products. This study conducts an experiment using LECA and EPA to produce lightweight concrete for structural use. Density, concrete quality, and strength of various mixes are observed by conducting cube compressive test and UPV test. Two phases of experiments were conducted, where the first phase variable is the percentage of LECA replacing the normal coarse aggregate, while the second phase variable is the percentage of EPA replacing the sand proportion. The optimum concrete mix is found to be the mix with 60% LECA and 50% EPA replacements, which achieved D1.8 lightweight density category that surpasses the specified minimum cube compressive strength and falls under the good quality concrete type according to the UPV rating. In summary, the inclusion of LECA and EPA into the concrete mix will decrease the cube compressive strength, lower the density, escalate the slump value and the travelling time of the ultrasonic pulse, but at the same time able to produce lightweight structural concrete

A Review of the Configurations, Capabilities, and Cutting-Edge Options for Multistage Solar Stills in Water Desalination

The desalination of saltwater is a viable option to produce freshwater. All the desalination processes are energy-intensive and can be carried out on a large scale. Therefore, producing freshwater using renewable energy sources is the most desirable option considering the current energy crisis and the effect that fossil-fuel-based energy has on our carbon footprint. In this respect, the tray-type still, one of several solar power desalination still varieties, is popular owing to its straightforward design, economic materials of construction, and minimal maintenance requirements, especially in isolated island regions with restricted energy and natural water supplies. The traditional tray-type solar power has a few drawbacks, such as the inability to recover latent heat from condensation, reduced thermal convection, a large heat capacity, and comparatively minimal driving power through evaporation. Therefore, the improvement of heat and mass transfer capabilities in tray-type stills has been the subject of many studies. However, there is a lack of a comprehensive review in the open literature that covers the design and operational details of multistage solar stills. The purpose of this paper is to present a thorough overview of the past research on multistage solar stills, in terms of configurations, capabilities, and cutting-edge options. In comparison to a unit without a salt-blocking formation, the review indicates that a multistage distillation unit may run continuously at high radiation and generate pure water that is around 1.7 times higher than a unit without a salt-blocking formation. The most effective deign is found to be “V”-shaped solar still trays that attach to four-stage stills, since they are less expensive and more economical than the “floor” (Λ-shape) design, which requires two collectors. Additionally, it can be stated that the unit thermal efficiency, solar percentage, and collected solar energy (over the course of a year) increase by 23%, 18%, and 24%, respectively, when the solar collectors are increased by 26% (at the constant inflow velocity of the water)