e utilization of desert sand for making ceramsite lightweight aggregate concrete is proposed to make full use of local natural resources in the development of a new type of lightweight and load-bearing wall material with good energy conservation, waste utilization, and thermal insulation performances. An orthogonal test was conducted to analyze the effects of the water-binder ratio, sand ratio, desert sand substitution rate, and fly ash content on the slump, apparent density, and tube crushing strength of desert sand ceramsite lightweight aggregate concrete. us, the optimal mixture ratio of the desert sand ceramsite concrete was obtained for the LC20 and LC25 strength grades. Based on two reasonable mixture ratios, the physical and mechanical properties of the desert sand ceramsite concrete were investigated. e results revealed that the water-binder ratio, sand ratio, and desert sand substitution rate were the main influencing factors, and the influence law is essentially consistent with that of ordinary desert sand concrete. Based on the reasonable substitution rate of desert sand, the main physical and mechanical properties of the desert sand ceramsite lightweight aggregate concrete, such as the tube crushing strength, tensile strength, and thermal conductivity, satisfied the requirements of the Chinese code's specifications. In summary, desert sand can replace ordinary sand in ceramsite lightweight aggregate concrete for the production of new lightweight and load-bearing wall materials.

No abstract

This paper proposes a hybrid seismic isolation system composed of geotechnical (a layer of sand or gravel as foundation soil) and structural isolation (a low-friction foundation sliding layer), aiming to effectively improve the seismic performance of rural buildings with an economical solution. The isolation system is most suitable for low-rise buildings in high-seismic areas. It is also effective in colder climates as replacing sand or gravel as the foundation soil eliminates frost heave. Shake table testing of three 1/4 scale models of two-story masonry buildings was carried out: an unreinforced brick masonry structure (model MA, without isolation), an identical structure with geotechnical isolation (model MS, with a layer of gravel as the foundation soil), and an identical structure with hybrid geotechnical and structural isolation (model MC). The dynamic characteristics and responses of the three structures were assessed and compared. Test results showed that shear failure of brick walls of model MA occurred at the first story when the input peak ground acceleration reached 0.44g. For model MS, a similar shear failure mode occurred when the acceleration reached 1.02g. Model MC relied on the layer of gravel for isolation before 0.44g, and then several cracks occurred at the foundation sliding layer, which was a sign of sliding. The plastic damage was mainly concentrated in the second story, and model MC showed bending-dominated deformation when the acceleration increased to 1.24g. This study clearly demonstrates the improved seismic performance and technical feasibility of the cost-effective hybrid isolation system.

In order to alleviate the shortage of sand resources for construction, make full use of industrial waste and promote the development of green lightweight aggregate concrete in the desert and surrounding areas, this paper proposes a new lightweight ceramsite concrete, fly ash cenospheres and desert sand ceramsite concrete (FDCC). An orthogonal test was conducted to analyze the effects of the desert sand (DS) replacing ratio, fly ash cenosphere (FAC) replacing ratio and polymer emulsion (PLE) addition on the damage patterns, slump, apparent density and compressive strength of the FDCC. The results showed that the most influential factors for the slump, apparent density and compressive strength of the FDCC were the FAC replacing ratio, FAC replacing ratio and DS replacing ratio, respectively. Meanwhile, the PLE addition had little effect on the workability or mechanical performance of the FDCC. With the increase in the DS replacing ratio, the slump decreased rapidly and the compressive strength reached its peak value, increasing by 20.6% when the DS replacing ratio was 20%. With the increase in the FAC replacing ratio, the slump increased by 106%, the apparent density decreased gradually and the compressive decreased and then increased, reaching its lowest value when the FAC replacing ratio was 20%. According to the synthetic evaluation analysis, the optimum DS replacing ratio, FAC replacing ratio and PLE addition of the FDCC were 20%, 30% and 1%, respectively.