This paper addresses the reaction of alkali activated slags (AAS). First, from literature the most abundant hydration products formed from the hydration of slags are summarized. These products include C-S-H, a hydrotalcite-like phase, a hydrogarnet phase, AFm phases (C4AH13 and CzASHs) and ettringite. Then, two reaction models are established which correlate the mineral composition of the slag (the glass part) with hydration products. Using the proposed models, quantities of hydration products and composition of C-S-H formed can be determined. Finally, the models are applied to four slags selected from literature, and conclusions are drawn.

The influence of silica fume (SF) on the plastic viscosity, yield point and gel strength of cementitious paste has been studied. A super-plasticizer based on polyacrylate with grafted polyether chains (SSP) was used. The effect of delayed addition of super-plasticizer versus addition with the mix water was investigated as well as the effect of densified versus untreated silica fume. Inert limestone slurries with SF replacement were used as comparison. The results showed that there was not much to gain in terms of lower shear stress in flow curves by delayed addition of this particular SSP. The plastic viscosity had a de-creasing tendency with increasing SF replacement, while yield stress was rather constant. Plastic viscosity increased with increasing time. There was a substantial increase in 10 min gel strength with increasing SF replacement. Gel strength was lower for mixes with densified SF versus untreated SF. Delayed SSP addition reduced gel strength for cementitious pastes with 10% SF. Neutral limestone pastes with increased SF replacement had increasing gel strength from 6 vol% replacement. Densified silica fume gave 10 times less gel strength than untreated SF. Increasing pH from 8 to 13.2 in limestone slurries with 10 vol% SF increased the shear stresses substantially.

Chloride ingress into concrete is commonly modeled using Fick's second law of diffusion. The common form of Fick's second law was derived for the boundary condition of one surface being in contact with a reservoir of constant concentration, such as the submerged portion of a marine seawall. However, in structures exposed to cyclic wetting and drying, this constant concentration boundary condition is not satisfied. Essentially, in cyclic exposures the surface concentration is not constant, but increases as a function of time. Chloride ingress occurs through sorption and diffusion in such exposures, but solely through diffusion in saturated environments. This paper compares the difference between chloride ingress in concrete exposed to cyclic wetting and drying environments with that of submerged concrete. This multi-year evaluation consisted of six different concrete mixtures, five of which contained different supplementary cementing materials. In addition, each concrete mixture was tested with and without a surface applied silane sealer. The results of these evaluations illustrate the relative rates of chloride ingress in the different environments and the effectiveness of supplementary cementing materials when combined with a silane sealer to reduce chloride ingress in cyclic exposures.

The early age strength development of concretes containing fly ash and ground granulated blast furnace slag has been investigated in order to give guidance for their use in fast track construction. Their use in concrete, although economic, has not gained popularity in fast track construction because of the slower strength gain of these concretes at standard curing temperatures. There are however indications that these cement replacements are heavily penalised by the standard curing regimes. The continuous measurement of the in situ temperatures during a UK Concrete Society Core Project has allowed the early age strength development of concretes in full-scale structural elements to be monitored. The effects of a range of environmental conditions and structural element parameters, including cement replacements, on the early age temperature history and hence the strength development of these concretes has been quantified. High early age temperatures are shown to be especially beneficial to ground granulated blast furnace slag concretes.

High fluidity concrete needs appropriate amount of powder for preventing concrete segregation. But slump flow often decreases because of the properties of powder. It is important to investigate qualities of the powder influencing rheological properties of concrete. So, the purpose of this study is to investigate an evaluation index for segregation resistance and the qualities of powder relating to the index. Firstly, the evaluation indices for segregation resistance were examined. And the best proposed as the ratio between coarse aggregate weight in concrete contained in the lower part of cylindrical vessel and that in upper part after tamping by a steel rod. This index more accurately ex-pressed the segregation potential under construction. Plastic viscosity of mortar and volumetric percentage of coarse aggregate in concrete mainly influence the index. Next, we investigated the influence of fly ash, Blast-furnace slag powder, limestone powder, crushed stone powder and recycled concrete powder on properties of a mortar. If the surface of powder was rough, the mortar flow with the powder largely decreased with in-creasing plastic viscosity when quantity of the powder was increased.