The high cost of the solar tracking systems is the major obstacle facing the growth of the solar harvesting technology. Therefore, reducing the solar tracking cost is necessary for developing this important energy sector. This study developed a simple and low-cost solar tracking system for parabolic concentrator (PCST) assisting tubular solar still (TSS). A single-axis solar tracking mechanism is developed based on two small light-dependent resistors (LDRs) shielded by a blank sheet which keeps the two cells shielded from sunlight. When the sunlight moves, one of the two LDRs will gain some light activating a switch to turn on the driving motor moving the system in the opposite direction till the LDR shielded again. By this simple mechanism, the two LDRs are shielded from sunlight all the time and consequently, the solar collector is always facing the sunlight. A simple parametric study is also conducted for an efficient PCST-TSS device with higher freshwater productivity. The performance of the most promising five design categories is compared. Results showed that the lowest cost tracking system was 34.6% lower than the highest one. Moreover, the lowest CPL was $0.0074/L which is 43.1% lower than the highest CPL category. Moreover, a comparison with other studies showed high potential for the present significant reduction in the cost which ranges between 43.1% and 87% compared with the recent related studies. The developed device is fully self-reliance and suitable for rural and isolated communities having limited infrastructure.

The exterior surface damage of concrete is a major problem for sub-structures and super-structures which are manufactured from concrete. In recent years, the protection of concrete exterior surfaces has attracted the attention of many researchers. This paper shows that alkaline activator coating materials (AACM) are used for curing concrete exterior surfaces. The curing of the concrete exterior surface with AACM helps to significantly reduce porosity in most products of building construction materials like hardened concrete and mortar plasters when they applied to their exterior surface. A chemical reaction occurs with unreactive Portland cement on the concrete exterior surface that always binds silicates to the concrete surface which in turn leads to decrease sucking of water into the concrete exterior surface. AACM can penetrate with the concrete exterior surface which helps to increase the deepness of waterproofing applied to the concrete exterior surface. The operation is simple to use, leaves no remnant and dries in a short time. It is ideal when it’s used on the concrete exterior surface and additionally it is appropriate for types of concrete exterior faces. The results presented the positive effect of alkaline activator coating materials AACM on the visual appearance, water-absorption, water-penetration, and sulfate attack. Alkaline activator coating has the same performance, but it would be cheaper when compared to the oil-based products.