Natural-Fibrous Lime-Based Mortar for the Rapid Retrofitting of Heritage Masonry Buildings

Study on the Durability of Hydraulic Lime Soil Mixed with Sodium Methyl Silicate

Natural hydraulic lime soil has good mechanical properties; as an earthen ruin restoration material, its durability is insufficient. Despite natural hydraulic lime being a topic that has been studied for several years from different researchers, it has not yet been fully considered for the improvement of durability. This work aims to experimentally investigate the enhancement of the durability properties of hydraulic lime-based. The performance of natural hydraulic limestone by adding sodium methyl silicate and organic silicon is examined and the effect of adding sodium methyl silicate on its performance and microstructure is studied. The 6%, 10%, and 15% lime–soil comparison test blocks of sodium silicate were compared with different lime–soil comparison test blocks not mixed with sodium methyl silicate; in addition to compression resistance, shear resistance, water absorption, and erosion resistance, dry–wet cycles were carried out, as well as microstructure testing and analysis. The results show that the addition of sodium methyl silicate enhances the compressive strength of hydraulic lime-modified soil, reduces its saturated water absorption, reduces its shear strength, improves its resistance to dry and wet cycles, and forms on the surface of the modified soil particles. The hydrophobic layer further improves its erosion resistance and water resistance. When the sodium methyl silicate content is 0.3%, the natural hydraulic lime soil has good mechanical properties and good durability, which is the optimal ratio.

An Investigation of Mechanical Properties of Concrete by Applying Sand Coating on Recycled High-Density Polyethylene (HDPE) and Electronic-Wastes (E-Wastes) Used as a Partial Replacement of Natural Coarse Aggregates

Plastic wastes are a major hazard for the environment and their use in the construction industry is increasing day by day. The major drawback of the use of plastic in concrete is an exceptional reduction in strength and workability. This research work explores the effect of sand coating on two types of recycled plastic aggregates, high-density polyethylene (HDPE) and electronic-wastes (E-wastes), as partial replacement of natural aggregates. The replacement ranged from 0% to 30% along with the use of super plasticizer SP-675 and wet lock sealant. Both recycled plastic aggregates are crushed, melted, and ground to convert them into aggregates of 20 mm size. The workability of concrete containing uncoated recycled plastic aggregates (HDPE and electronic wastes), SP-675, and wet lock sealant has been found to be higher than controlled concrete samples with 0% recycled aggregates. Compressive strength, split tensile strength, and flexural strength of such type of concrete is lower than the controlled concrete samples due to the weak bond between the plastic aggregates and Ordinary Portland Cement. After applying the sand coating to improve bonding, the workability is reduced compared to uncoated samples whereas the compressive strength, split tensile strength and flexural strength of the sand coated plastic aggregate concrete is higher than uncoated plastic aggregate concrete. There is a significant increase in workability of concrete after the addition of SP-675 when added as 2% by weight of cement. The wet lock sealant positively affects the strength properties of concrete. It is recommended that the durability of concrete containing uncoated and sand coated recycled plastic aggregates be further explored in future studies.