Comparison of physical and mechanical properties of river sand concrete with quarry dust concrete

This study compared the physical and mechanical properties of river sand concrete with quarry dust concrete. The constituent materials were batched by weight. The water-cement ratio and mix ratio selected for the experimental investigation were 0.55 and 1:2:4, respectively. The specimens were cured for 7, 14, 21 and 28 days. Slump, density and compressive strength tests were carried out. The results showed that river sand concrete had greater density and compressive strength than quarry dust concrete for all curing ages. At 28 days of curing, river sand concrete exceeded the target compressive strength by 36%, whereas quarry dust concrete was less than the target compressive strength by 12%. Both river sand concrete and quarry dust concrete for the selected water/cement ratio and mix ratio are suitable for non-structural applications and lightly-loaded members where high strength is not a prerequisite

Plastic buckling of thin flat rectangular isotropic plates under uniaxial in-plane loads

This study presents the analysis of plastic buckling of thin flat rectangular isotropic plates. To actualize this, the deformation theory of plasticity by Stowell’s approach is used in expressing the governing differential equation, and this equation is modified by adopting the method of work principle based on the principle of conservation of energy. Taylor-Maclaurin series functions truncated at the fifth term is used in estimating the deflection functions. The analyzed plates are subjected to uniform uniaxial in-plane compression and the direction of the loading is in the longitudinal direction (x-axis). The three plate boundary conditions considered in this study are: four simply supported edges (SSSS); four clamped edges (CCCC); and two clamped edges along the x-axis and two simply supported edges along the y-axis (CSCS). The Taylor-Maclaurin series formulation satisfied each of the plate boundary conditions and resulted to a distinct deflection function for each plate. These deflection functions are substituted into the governing equation to obtain the critical plastic buckling loads. Values of the buckling coefficient, k, which is derived from the critical plastic buckling load equation, are calculated for aspect ratios, p, ranging from 0.1 to 1.0 in steps of 0.1, using values of moduli ratio, Et/Es, equal to 0.6, 0.7, 0.8, and 0.9. The results are compared with those of a previous investigation. The percentage differences of k with plastic buckling solutions for the different values of p and Et/Es of the plates ranged from −4.685% to 6.276%. It is shown that the technique proposed in this study is an alternative approximate method for analyzing the plastic buckling of thin rectangular isotropic plates under uniform uniaxial in-plane loads

Physico-mechanical behaviour of sandcrete produced with different proportions of sand grain sizes

The physical and mechanical properties of sandcrete produced with various blended proportions of sand grain sizes were investigated. River sand was sieved into three portions with distinct grain sizes. These were: sand containing only grains with diameters less than 1 mm (fine sand), 1-2 mm (medium sand) and 2-4 mm (coarse sand). Seven different combinations of grain sizes were proportioned by weight, with each combination containing 50% fine sand. Five cement/sand mix ratios, 1:4, 1:5, 1:6, 1:7 and 1:8, were used for moulding 150 × 150 × 150 mm sandcrete cubes. The results revealed that an increased proportion of coarse sand tended to increase the bulk density and compressive strength of sandcrete cubes after 28 days of curing. The grain size combination which gave the optimum compressive strength of sandcrete contained 50% fine sand, 10% medium sand and 40% coarse sand