Thermal insulation and thermal energy storage are becoming more and more attractive for residential and industrial buildings due to the need of sustainable development. The economical and efficient technique that can be used to produce building products for insulation and store energy is also the subject of research for a long time. Cement-based products manufactured by extrusion technique offer advantages in terms of the flexibility of section profiles, material performance enhancement and mass production mode. Different fillers can be used to achieve desired effects on thermal, mechanical and physical characteristics during extrusion process. These fillers include sand and expanded perlite which are good at thermal insulation and phase change composites which can provide high energy storage capacities. It is foreseeable that extruded building products with suitable fillers have potentiality for economical applications for thermal insulation and thermal storage of different kinds of buildings.

The design versatility of cement-based composites continues to make them attractive for a variety of specialized applications. Advanced processing techniques, including the Hatschek process, extrusion, self-consolidating concrete and slipform-cast concrete paving, offer great promise for improving innovation in the modern construction world. However, to advance the state-of-theart of cement-based products, the fresh state characteristics of these materials need to be well understood. Processing has a significant impact on composite performance, affecting fresh and hardened state properties as well as overall cost. In spite of its importance, relatively little is known about the relationship between processing and composite performance. Recent work at the Center for Advanced Cement-Based Materials (ACBM), headquartered at Northwestern University, has focused on developing a better understanding of this critical relationship. The role of processing on composite performance has been examined for a variety of advanced processing techniques, including the Hatschek process, extrusion, self consolidating concrete and slipform-cast concrete paving. The results indicate that overall composite performance can be enhanced by controlling fresh state properties. This paper presents a review of these studies and discusses ongoing research to link composite performance to microstructural changes.

This CD-ROM consists of papers that were presented at a session sponsored by Committee 549 at the Fall 2007 Convention in Fajardo, Puerto Rico. The objective of the symposium was to have a state-of-the-art review on the development of fabrication methods for cementitious products and explore their potential market opportunity in residential and industrial building applications. Note: The individual papers are also available. Please click on the following link to view the papers available, or call 248.848.3800 to order. SP-260

Extruded high-performance fiber-reinforced cementitious composites (HPFRCC) offer a number of benefits over the materials currently used in residential construction, including improved strength, ductility and durability, increased design flexibility, improved safety in the event of natural hazards and greater affordability. Despite these benefits, the use of extruded HPFRCC is not widespread in North America. Current extruded HPFRCC are difficult to nail, requiring excessive force to nail and often cracking due to nailing stresses. Research at the Center for Advanced Cement-Based Materials (ACBM), headquartered at Northwestern University, has focused on developing nailable extruded composites. Using a previously developed test method, the nailing performance of extruded HPFRCC was evaluated and compared with commercial products. Existing cavity expansion- and fracture mechanics- based models were used to determine the material parameters required for nailing. The results indicate that by tailoring both the matrix and the fiber reinforcement, nailable extruded composites can be produced. Nailable extruded HPFRCC have a reasonably low density and compressive strength (to allow for nail penetration) and a high fracture toughness (to resist cracking due the nailing stresses).

Carbonation curing of cellulose fiberboard made by slurry-dewatering process was studied to examine their CO2 uptake capability, immediate carbonation strength and long term strength after subsequent hydration. Influencing parameters on CO2 uptake and strength gain were discussed. They included compact forming pressure, drying time, drying temperature, carbonation duration, fiber/cement ratio and water/cement ratio. It was found that cement bonded cellulose fiberboards had excellent carbonation capacity. The percent carbon uptake ranged from 13.5 % to 23.6%, based on cement content and process conditions. High degree of carbonation significantly improved early age strength and had no detrimental effect on the subsequent hydration strength. To promote more CO2 uptake and higher strength gain, carbonation rate should be controlled. This can be achieved through system optimization. Carbonation curing has shown the potential to replace traditional autoclaving and gain technical, economical and environmental benefits.