Experimental Performance Measures of Recycled Insulation Concrete Blocks from Construction and Demolition Waste

Construction and demolition(C&D)waste has seriously affected the ecological environment.The utilization of C&D waste resources can greatly alleviate this problem,and it is an important way to help achieve the goal of zero carbon in 2050.In this study,insulation concrete blocks were developed with recycled aggregates,cement,fly ash as main raw materials,expanded polystyrene(EPS)insulation boards as block insulation filling material,and selfdeveloped construction waste composite activator,interface enhancer,surface modifier and other additives.Through experimental research and performance test analysis,the best mix ratio of the product and the mechanism of each additive were proved.The experimental results showed that the insulation concrete block prepared under the conditions of recycled aggregates sand ratio of 45%,active activator Na_(2)SO_(4)content of 0.15%and fly ash content of 30%has the best performance and meets the relevant standards.

RESIDENTIAL LIFE CYCLE ASSESSMENT MODELING: COMPARATIVE CASE STUDY OF INSULATING CONCRETE FORMS AND TRADITIONAL BUILDING MATERIALS

Innovative,sustainable construction products are emerging in response to market demands.One potential product,insulating concrete forms(ICFs),offers possible advantages in energy and environmental performance when compared with traditional construction materials.Even though ICFs are in part derived from a petroleum-based product,the benefits in the use phase outweigh the impacts of the raw material extraction and manufacturing phase.This paper quantitatively measures ICFs’performance through a comparative life cycle assessment of wall sections comprised of ICF and traditional wood-frame.The life cycle stages included raw materials extraction and manufacturing,construction,use and end of life for a 2,450 square foot house in Pittsburgh,Pennsylvania.Results showed that even though building products such as ICFs are energy intensive to produce and thus have higher environmental impacts in the raw materials extraction and manufacturing phase,the use phase dominated in the life cycle.For the use phase,the home constructed of ICFs consumed 20 percent less energy when compared to a traditional wood-frame structure.The results of the impact assessment show that ICFs have higher impacts over wood homes in most impact categories.The high impacts arise from the raw materials extraction and manufacturing phase of ICFs.But there are a number of embedded unit processes such as disposal of solid waste and transport of natural gas that contribute to this high impact and identifying the top unit process and substance contributors to the impact category is not intuitive.Selecting different unit processes or impact assessment methods will yield dissimilar results and the tradeoffs associated with every building product should be considered after studying the entire life cycle in detail.

THE LIMITATIONS OF LEED: A CASE STUDY

The Xanterra houses are situated against the backdrop of one of America’s most spectacular natural landscapes,just a few hundred yards from the north entrance to Yellowstone National Park.The project consists of two single-family homes for seasonal workers,approximately 2000 square feet each.They are mirrored east-to-west but otherwise identical(see Figure 1).The project was completed in 2003,and certified under LEED-NC v2.0,project#1353 on December 10,2004-the first building project in the National Park system to receive LEED(Leadership in Energy and Environmental Design)certification from the USGBC(United States Green Building Council).1 The houses were built with the explicit intent that they would become a model for future green building projects at Yellowstone and other national parks,2 and the project team felt it was fitting that these houses be situated in the nation’s first national park.Indeed,they were fundamentally well-designed and constructed,and they incorporated some of the latest technologies for saving energy and water,authentically earning the label“high-performance.”Yet the project only earned the lowest possible rating(“certified”)from LEED,meaning it is barely considered green.This paper documents the green design strategies through the design and construction process,with special attention paid to the influence of the LEED scorecard on collaborative decision-making and to the difficulties this project encountered during the LEED assessment process.Few academic studies have examined the process of LEED self-reporting and scoring within a professional setting,3 even though contingencies such as common business practices and human limitations clearly affect a project’s LEED score.This paper will show that the LEED scorecard turned out to be a poor assessment tool in this case study,because the reporting procedure inaccurately reflected the architectural design and construction.Furthermore,there have been a few important papers that conclude that a major problem of the LEED rating method is its failure to account for the building’s performance over its projected life.4 This paper will verify those conclusions by showing that the lifespan of concrete construction was not considered by the LEED rating process.The larger questions that stimulated this research are consistent with the problems that have motivated the current widespread interest in green design strategies:How can we design buildings that consume less energy?How can we use materials and construction practices more responsibly in terms of reducing pollution and waste?How should we evaluate our own practices to understand their true efficacy?These questions are particularly urgent for the American homebuilding industry,which has become increasingly extravagant and has lost sight of green design strategies in the design of its dwellings5(and increasingly wasteful in energy consumption).Since the Xanterra houses were consciously developed as a positive alternative to typical homebuilding practices,an analysis of their performance-from design through assessment-may have implications for future projects of a similar type.

HYGROTHERMAL PERFORMANCE ASSESSMENT OF ICF WALLS WITH DIFFERENT MOISTURE CONTROL STRATEGIES AND WALL DESIGNS

The initial high moisture content of concrete and the low vapor permeability of insu-lation layers on both sides of the concrete complicate the drying process of Insulated Concrete Forms(ICF).In order to facilitate the moisture transport and enhance the drying process,different moisture control stratcgics and wall designs can be implc-mented.The application of an air and vapor barrier is one of the most common moisture control stratcgics.In this paper,the impact of vapor permcance of an air and vapor barriers on the hygrothermal performance of an ICF wall in three differ cnt cold and wet climates is examined using a validated Hcat-Air-Moisture transfer model.The hygrothermal performance of an ICF wall assembly with different types of barriers and locations in the wall system for scveral wall designs is invcstigated.Results indicate that a smaller thickness of insulation on the outside facilitates remov-ing the moisture towards the outside and installing low permcance air/vapor barrier systems on the outside prohibits drying and drives the moisture to the inside.Our findings also show that with the proper sclection of insulation thickncss and vapor control stratcgy moisture-related problems can be avoided.