掺加微粉对高钛重矿渣砂浆性能的影响

通过对掺加不同含量的渣粉和粉煤灰在高钛重矿渣砂浆中的试验研究,验证了高钛重矿渣砂浆中适量的双掺矿渣微粉、粉煤灰可以改善砂浆拌合物的强度与和易性,满足砌体施工规范要求。

Sulfuric Acid Resistance of Concrete with Blast Furnace Slag Fine Aggregate

The deterioration of concrete by sulfuric acid attack in sewage environments has become a serious problem for many existing sewage structures. In this study, the properties of concrete using the blast furnace slag have been examined. It was shown that by using the blast furnace slag fine aggregate and blast furnace slag fine powder, it is possible to enhance the resistance of mortar and concrete to sulfuric acid. The resistance to sulfuric acid of mortar and concrete can be improved by using a blast-furnace slag fine aggregate in the total amount of fine aggregate. When mortar or concrete reacts to sulfuric acid, dihydrated gypsum film is formed around the particulate of the fine aggregate. This dihydrated gypsum film could retard the penetration of sulfuric acid, thus, improving the resistance to sulfuric acid. Furthermore, it has been proved that the relationship between the erosion depth by sulfuric acid attack and the product of immersion period and concentration of sulfuric acid can be expressed linearly. However, this relationship is dependent on the type of materials of concrete.

Effects of Al_2O_3 nanoparticles on properties of self compacting concrete with ground granulated blast furnace slag (GGBFS) as binder

In this work, strength assessments and percentage of water absorption of self compacting concrete containing ground granulated blast furnace slag （GGBFS） and A1203 nanoparticles as binder have been investigated. Portland cement was replaced by different amounts of GGBFS and the properties of concrete specimens were investigated. Although it negatively impacts the physical and mechanical properties of concrete at early ages of curing, GGBFS was found to improve the physical and mechanical properties of concrete up to 45 wt% at later ages. A1203 nanoparticles with the average particle size of 15 nm were added partially to concrete with the optimum content of GGBFS and physical and mechanical properties of the specimens were measured. A1203 nanoparticle as a partial replacement of cement up to 3.0 wt% could accelerate C-S-H gel formation as a result of increased crystalline Ca（OH）2 amount at the early ages and hence increase strength and improve the resistance to water permeability of concrete specimens. The increase of the A1203 nanoparticles＇ content by more than 3.0 wt% would cause the reduction of the strength because of the decreased crystalline Ca（OH）2 content required for C-S-H gel formation. Several empirical relationships have been presented to predict flexural and split tensile strength of the specimens by means of the corresponding compressive strength at a certain age of curing. Accelerated peak appearance in conduction calorimetry tests, more weight loss in thermogravimetric analysis and more rapid appearance of the peaks related to hydrated products in X-ray diffraction results, all indicate that A1203 nanoparticles could improve mechanical and physical properties of the concrete specimens.

Effect of ground granulated blast-furnace slag(GGBFS) and silica fume(SF) on chloride migration through concrete subjected to repeated loading

The effect of ground granulated blast-furnace slag(GGBFS) and silica fume(SF) on the chloride migration through concrete subjected to repeated loading was examined.Portland cement was replaced by 20%,30%,40% GGBFS and 5%,10% SF,respectively.Five times repeated loadings were applied to specimens,the maximum loadings were 40% and 80% of the axial cylinder compressive strength(f′c),respectively.Chloride migration through concretes was evaluated using the rapid chloride migration test and the chloride concentration in the anode chamber was measured.The results indicate that the transport number of chloride through concrete containing 20% and 30% GGBFS replacements and 5% and 10% SF replacements is lower than that of the control concrete,but 40% GGBFS replacement increases the transport number of chloride.Five loadings at 40% f′cor 80% f′c increase the transport number of chloride for all mixes investigated in this study.5% SF replacement has a very close effect on the chloride permeability of concrete with 20% GGBFS when concrete is subjected to 40% f′cor 80% f′c.