Investigation of Physical-Mechanical Properties and Microstructure of Mortars with Perlite and Thermal-Treated Materials.

This study aimed to obtain and characterize a mortar with perlite aggregate and thermal-treated materials that could substitute for Portland cement. First, the thermally treated materials were obtained by calcinating old Portland cement (OC-tt) and concrete demolition waste (CC-tt) at 550 °C, for 3 h. Second, plastic mortars with a perlite: cement volume ratio of 3:1 were prepared and tested for water absorption, mechanical strength, and thermal conductivity. The microstructure was also analyzed. Portland cement (R) was partially substituted with 10%, 30%, and 50% OC-tt. Thermal-treated materials negatively influenced the compressive and flexural strengths at 7 and 28 days. With an increase in the substitution percentage to 50%, the decrease in the compressive strength was 40% for OC-tt and 62.5% for CC-tt. The presence of 10% OC-tt/CC-tt positively influenced the water absorption. The thermal conductivity of the tested mortars was in the range of 0.37-0.48 W/m·K. SEM analysis shows the expanded perlite pores remained unbroken.

Reaction to fire, thermal, and mechanical properties of materials based on recycled paper granules bound with starch and clay mortar.

The objective of this work is to produce an ecologically friendly material for use in Ivory Coast's construction sector in the future. These materials should have good thermal qualities and be flame resistant in addition to helping to achieve interior comfort. The fundamental components under consideration are freely accessible in Ivory Coast and include clay mortar as a fire retardant, potato starch as a binder, and recycled paper granules as a filler. The suggested ecologically friendly material's manufacturing process is fully described in detail. After conditioning, the team created multiple samples, taking into account that each test that the materials are put through requires various probe sizes for the thermal conductivity test, the reaction to fire test, and the flexural strength test. The best result regarding thermal conductivity of composites was obtained when 10 % clay is added in the mixture, namely between 0.057 … 0.068 W/(mK). During the ignitability tests the flame did not propagate to a height greater than 15 cm throughout the 60 s test time, so it can be concluded that the materials match minimally in the class E of reaction to fire. The flexural strength of tested materials was under 0.8 MPa.

Assessment of Properties and Microstructure of Concrete with Cotton Textile Waste and Crushed Bricks.

Cotton textile waste (CW) and crushed bricks (CB) are wastes generated by the textile and construction industries that cause adverse effects on the environment. This paper explores the effect of adding 1, 2, 5, and 10 wt.% of CW and CB, instead of natural sand under 1 mm (50 to 100 vol.%), on the properties of concrete. The study included the analysis of workability, density, water absorption, thermal conductivity, mechanical strengths, and electron microscopy. The results show that the presence of CW and CB increased the water required to obtain the same slump value as reference, R. Concretes with CW provided better performance in terms of density, water absorption (for 1 wt.%), and splitting strength (for 1 to 2 wt.%). The 28 days of compressive strength decreased with increasing CW (33.3 MPa for R and 26.9 MPa for 2 wt.% of CW). The partial substitution of sand decreased the workability and density and increased the mechanical strength of concrete. The presence of both CW and CB decreased workability, density, and mechanical strengths. Regarding the ability of concrete to transfer heat, the addition of CW and CB decreased the thermal conductivity value (e.g., 0.32 W/(m·K) for 1 wt.% of CW compared to 0.37 W/(m·K) for reference).