Studies were conducted to determine the effects of a panel of seven nanomaterials (NMs), namely: α-alumina, γ-alumina, precipitated silica; silica fume, calcined silica fume, colloidal antimony pentoxide (Sb(2)O(5)), and superfine amorphous ferric oxide (Fe(2)O(3)), on sediment dwelling invertebrates Chironomus tentans under controlled laboratory conditions. Percentage survival, enzyme activiti...

Mortar with high workability even without a water-reducing agent and with high tensile and compressive strengths (3.1 and 78 MPa, respectively) was obtained by using as an admixture silica fume that had been surface treated with a silane coupling agent. The treatment enhanced the wettability of silica fume by water, thereby increasing the workability of the mortar mix. It also enhanced the bond...

In the Refractories world three decades ago, very few people were acquainted to silica fume and its usage. After a few years, it was used as an additive to brick. When added to high Alumina brick, mullite was formed in the matrix of the brick on firing, giving the brick good volume stability, strength and chemical resistance. When used in basic brick, high hot strengths resulted, at least at 27...

Current design practices based on descriptive approaches to concrete specification may not be appropriate for the management of aggressive environments. In this study, the durability of cement-based materials with and without the addition of silica fume, subjected to conditions that leach calcium and silicon, were investigated. Chemical corrosion was simulated by employing various H₂SO₄ and MgS...

This paper presents the effect of Sodium Chloride (NaCl) on Conventional Concrete (Silica Fume Based M30 Grade Concrete). The Silica Fume Based M30 Grade Concrete was prepared by adding NaCl concentrations of 0.5,2,4,6,8,10 and 12 g/l i n deionised water. In addition to this, control specimen was prepared with deionised water (without NaCl) for the purpose of co mpari son . The tensile strength...

This paper describes the low temperature synthesis of belite (β-C2S) from silica fume. Mixtures of lime, BaCl2, and silica fume with the ratio of (Ca + Ba)/Si = 2 were hydrothermally treated in stainless steel capsule at 110-150°C for 2-5 hours, calcined at 600-700°C for 3 hours, and analyzed by FTIR, XRD, TGA/DTA, and SEM techniques. Dicalcium silicate hydrate (hillebrandite) was prepared by h...

Without using strong alkaline solution or ordinary Portland cement, a new structural binder consisting of fly ash and hydrated lime was hardened through an intensified pozzolanic reaction. The main experimental variables are the addition of silica fume and initial thermal treatment (60 °C for 3 days). A series of experiments consisting of mechanical testing (compressive and flexural strength, m...

The present investigation revealed the effect of using silica fume and copper slag as a partial replacement of cement and fine aggregate, respectively on the mechanical properties of the concrete. Due to the depletion of natural sand resource worldwide with the increment of industrial waste, simultaneously, partial replacements of fine aggregate with copper slag have been attempted. Therefore, ...

A series of concrete slabs were cast with 0, 7, and 12% by mass silica fume replacement of cement at W/CM = 0.35, 0.40, and 0.45. After either moist or steam curing, a variety of chloride resistance tests were performed. These included AASHTO T259, modified T259, T277, as well as several bulk diffusion tests and sorptivity tests. Results indicate that the use of properly dispersed silica fume r...

Sulfate attack is a series of physico-chemical reactions between hardened cement paste and sulfate ions. Sulfate ion penetration into the hydrated cement results in the formation of voluminous and deleterious phases such as gypsum and ettringite which are believed to cause deterioration and expansion of concrete. Concrete deterioration due to sulfate attack depends on many parameters, however, ...