Reactivity of Recycled Glass Powder in a Cementitious Medium

The reactivity of the recycled glass powder (GP) in a cementitious medium has been studied over time by means of X-ray diffraction and thermal gravimetric analysis. Two different mixtures based on cement/glass powder (0 or 20 wt% GP) and lime/glass powder (70 wt% GP) were considered. Analysis revealed the coexistence of both hydration and pozzolanic reaction during the hardening of the mortars. At young age, the cement hydration would prevail over the pozzolanic one resulting in a decrease of physico-chemical and mechanical properties of the material due to the dilution effect. The pozzolanic reaction that predominates from 91 days, would induce the formation of supplementary C-S-H leading to improve the material properties.

Effect of Glass Powder on Concrete Sustainability

As defined by the American Concrete Institute (ACI), alternative supplementary cementitious materials (ASCMs) and local materials are very important in concrete sustainability. As an ASCM, glass powder (GP) shows excellent pozzolanic properties. This paper focuses on characterization and the effect of GP on concrete properties compared to those of Class F fly ash (FFA) and ground granulated blast furnace slag (GGBS). Concrete incorporating 0, 20 and 30% of GP and other concrete mixes containing 30% of FFA or GGBS were cast. The concrete mixes considered in this study have water to binder (w/b) mass ratio ranging from 0.35 to 0.65. The mechanical properties such as compressive strength and durability including chloride ions permeability and chloride ions diffusion are evaluated. The results show that GP develops effects on mechanical properties similar to those of FFA and performs better than GGBS and FFA in terms of permeability reduction. GP reduces dramatically chloride permeability of concrete regardless w/b ratio, favoring an improvement of the concrete durability. Because of the interesting permeability developed by concretes incorporating GP, its use as an ASCM is promising.

Reactivity of Fine Quartz in Presence of Silica Fume and Slag

Dune sand is a very abundant material in south of Algeria. Its high silica content gives a partial pozzolanic reactivity due to its crystalline state. This paper investigates the evolution of cement hydration based on a binary addition particularly the reactivity of dune sand finely ground in the presence of an amorphous addition: silica fume or blast furnace slag. Thus, four combinations of binary additions by substitution have been chosen. The X-ray diffraction analyses performed on cement pastes containing additions have shown the importance of the mineralogy and silica content of additions on their pozzolanic reactivity. Dune sand becomes reactive at long term, especially when associated up to 10% of amorphous addition (blast furnace slag or silica fume). It results an increasing in mechanical strength of Ultra High Performance Concrete (UHPC) and an improvement of the microstructure.

工业和农业废弃物在混凝土中的本地资源化利用:可持续解决方案（英文）

全球变暖是当今社会面临的主要环境问题，是由过量二氧化碳排放造成的。水泥生产过程中石灰石的分解和燃料的燃烧排放的CO2量占据了总排放的5％～8％。随着民用基础设施建设的快速发展，特别是在中国、印度、中东等发展中国家，水泥和混凝土使用量飞速增长。采用辅助胶凝材料替代混凝土中水泥的使用量，尤其是工业废弃物，能够显著降低了混凝土生产过程中的碳排放。普通的工业废弃物，如硅灰、粉煤灰、矿粉等并不是全部可以利用的，较远距离运输会造成CO2总排放量的增加。然而，铝生产工业的其他副产物和废弃纸泥灰也可以作为辅助胶凝材料进行循环利用的。农业生产中的废弃物，如甘蔗灰、棕榈油灰、椰子壳灰、稻壳灰等也有火山灰特性，能够将其作为辅助胶凝材料使用。此外，一些天然掺合料，如硅藻土含有丰富的火山灰活性组分。近年来，玻璃粉作为辅助胶凝材料在很多国家广泛应用。上述辅助胶凝材料的循环利用能够降低混凝土对环境影响，且能有效减少相关生产费用。