Low Density, High Compressive Strength: Experimental Investigation with Various Particle Sizes of Sand for Different Mix Designs of Cement Mortar Manufacturing

Concrete density was optimised by substituting part of the normal-density aggregates (fine aggregate, coarse aggregate, or both) with that of comparable quantities of low-density aggregate, which enhanced structural efficiency (strength to density ratio), improved hydration and decreased transportation costs. These days, focus is given on enhancing the characteristics of concretes in order to make them more efficient. A factor associated in compressive strength, packing particle, water absorption and density is concrete proportioning. A good proportioning mix results in greater strength for concrete at optimum density and specified age. The filler effect is regarded as a physical feature pertaining to small particles for a concrete material since it allows generating extra compressive strength by filling voids by making mortar or concrete more homogeneous. This behaviour allows conferring additional compressive strength as well as optimise or minimise the concrete's density without having to use a pozzolanic reaction or a chemical reaction. Mainly, this objective has been implemented through using three different lightweight particle sizes of sand group a-(1.18 mm ≤ Sand size < 200 ɱm), b-(2.36 mm ≤ Sand size < 1.18 mm) and (5.0 mm ≤ Sand size < 2.36 mm). The parameters that are taken consideration during the investigation were sand particle size, water/cement ratio, cement/sand ratio. In general, the results demonstrated that there was a decrease in compressive strength when the sand's particle sizes increased. In case the particle size group (b) and (c) used the decrease rate in compressive strength was 7.97% and 12.39% respectively in comparison with particle size group (a) where the optimum values of the water/cement and cement/sand ratio were used. On the other hand, low density was achieved at the point of the higher compressive strength, whereas 4.4% and 3.66 % increase in the density was recorded over the particle sizes of sand (b and c) respectively. Meanwhile, we put forward the relationships existing between the compressive strength as well as density of concrete mixtures with various proportions of the lightweight aggregates as given above. The conducted experimental studies showed that there were tendencies to possibly utilise various quantities of fine lightweight aggregates as well as their combinations to yield concrete mixtures based on the requirements in practical application. As per the study conclusion, the considered mixtures could be used to yield structural elements that need high compressive strength and lower density.