Green binding material using alkali activated blast furnace slag with silica fume

Recently million tons of cement is produced in Egypt accompanied with million tons of CO2 emission which causes annually negative impact on the environment. Granulated blast furnace slag and silica fume are produced as by-product from iron and chemical industries with limited recycling facility. This paper represents an experimental study aimed to safe ferrosilicon alloy of slag and silica fume to produce cementless binding material using both of Sodium Hydroxide and water glass liquid (Sodium Silicate) as alkaline activator. Experimental program was designed to study silica/slag ratio, percentage of alkali activator, water/binding ratio, incorporation of superplasticizer, and curing condition on the properties of the produced binding material. Compressive strength and mineralogical analysis were conducted on the polymeric binding material to asses the effectiveness of the main variables. The tests were divided into two stages; in the first stage compressive strength was conducted for all mixes while X-ray, microscopic scan (SEM), and infrared analysis (IR) were carried out for the most pronounced promising mixes. The results showed that ratio of 25% of silica/slag is the most effective ratio and 5% of each of Sodium Hydroxide and Sodium Silicate was the optimum percentage of the alkaline activator. Additionally the use of superplasticizer is essential as it positively reduces the mixing water and maintains the binding material with acceptable workability

Performance evaluation of interlocking paving units in aggressive environments

This study evaluates the performance of interlocking paving when exposed to aggressive environments. Durability of paving units is an essential property as it determines its capability of withstanding the different conditions to which it is expected to be exposed to- Chemical, physical, and mechanical causes can result in lack of durability. Chemical cause can arise from attack by chlorides, physical cause may be due to exposure to high temperature variations, while mechanical causes are usually associated with abrasion. Experiments were carried out to determine product compressive strength, water absorption, and abrasion resistance according to both Egyptian Standard Specifications (ESS) and American Society for Testing and Materials (ASTM). An interlocking paving mix was chosen and exposed to various aggressive media for a duration of 2 months after being cured for 28 days. The aggressive environments were as follows: 1% HCl, 5% HCl solution (to simulate acid attack resistance), dry and wet cycles, as well as, air (room temperature) and dry cycles (to simulate different environmental conditions). The tested products were also X-rayed to investigate the mineralogical analysis. The following was concluded. The four aggressive media increased compressive strength when compared to the control mix. Also, they resulted in reducing water absorption percentages and met the criteria for water absorption concerning heavy duty according to ESS. Samples which were exposed to the four aggressive environments conditions did not satisfy both criteria of ESS and ASTM pertaining abrasion