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For the repair and strengthening of historical masonry structures, high penetrability injection grouts which use lime, natural pozzolan, portland cement and some with silica fume have been developed. The type, morphology and evolution of the microstructure and hydration products as evidenced by mercury intrusion porosimetry and X-ray diffraction are presented. Furthermore, the evolution of the insoluble residue and soluble silica contents is also presented. The results of mechanical and bonding tests are presented. Grout mixtures at different ages up to 180 days are compared. The results indicate that ternary blends of the type lime-natural pozzolan-normal portland cement with or without addition of silica fume are highly sensitive to curing conditions. If appropriate curing and quality control are applied, the grout mixtures developed very good mechanical properties and address both durability and economy issues.

Corrosion is one of the dominating causes of deterioration of reinforced concrete structures. Carbonation of concrete can initiate the corrosion of reinforcements. Many parameters are affecting the concrete carbonation process. Due to the combination of these parameters, phenomenon of concrete carbonation is very complex. It is therefore necessary to implement numerous experimental works to find the relationship between input and output parameters. These tests are slow and time-consuming. On the other hand t h e great number __ of __ r eq uir ed tests makes the investigations costly. Thus it is worth to use numerical methods as new tools to find the relationships between input and output parameters. Neural Networks are capable of showing the relationships of inputs and outputs even in complex nonlinearity. They can be used even in the cases of little background of the theoretical rules, which govern the phenomenon. Due two these advantages of neural networks, a new model of concrete carbonation (NNCC) have been developed to show the appropriateness of the neural networks in civil engineering fields especially in advanced concrete technology, together with its usage as a new prediction model instead of conventional fitted type models.

Materials prepared by agglomerating white sand and slag with lime were subjected to infiltration with supercritical CO2 at temperatures from 3 1 to 40 OC, pressures from 7.4 to 10 MPa, and for periods from 20 to 120 min. This technique quickly promotes the carbonation reactions which are responsible for the development of the cementitious properties of the composite material. T h e extent of carbonation inside 50 mm cubes was monitored by using phenolphthalein, and the crystalline species were determined by X-ray diffraction. The results showed a high conversion (greater than 74%) of lime to calcite. After infiltration, all specimens exhibited a significant increase in compressive strength. From these results, we conclude that it is possible to produce improved carbonated materials in short processing times. The infiltration technique may be useful for producing construction materials from a number of siliceous waste products such as slag, construction rubbish and sludges from water-treatment plants.

Concrete specimens were manufactured by completely replacing natural aggregates with recycled aggregates from a crushing plant in which rubble from building demolition was ground. Various concrete was prepared by using silica fume or fly ash as a partial fine aggregate replacement and by using an acrylic polymer based superplasticizer to achieve the prefixed workability. Three types of recycled aggregate concrete were manufactured with the same water/cement (0.40) and the same fresh workability (fluid consistency). A reference concrete was also prepared by using natural aggregates with the same particle size distribution as the recycled aggregate, and having a water/cement of 0.56 and a similar fluid consistency. The results obtained show that because of mineral addition and W/C reduction, recycled aggregates can be used instead of natural aggregates since concretes with similar compressive strength can be obtained. The use of the recycled aggregates with fly ash replacements also has significant cost and environmental advantages over ordinary concrete.

This paper reports the results of an investigation of the sorptivity of mortar that contains varying amounts of ground brick from different European bricks. Waste clay brick deriving from four European countries was ground to roughly cement fineness and used to partially replace cement in quantities of 0, 10, 20 and 30% in mortars. The sorptivity and water absorption of these mortars were tested for curing periods of up to one year. The presence of ground brick does not have a significant effect on the water absorption of mortar. Sorptivity however, is affected considerably by not only the presence of ground brick but also by brick composition. Initially, the presence of ground brick in mortar increases its sorptivity. As curing periods increase, the sorptivity values for ground brick mortars decrease at a rate that is greater than that seen in mortars whose binder is 100% portland cement. This indicates that the ground brick decreases the capillarity of the mortar and this is attributed to the production of additional C-S-H gel. The additional C-S-H gel, in effect, refines the pore structure of the mortar and this is reflected in the increase in the compressive strength obtained for these mixes.