Lightweight concrete (LWC) finds wide-ranging applications in the construction industry due to its reduced dead load, good fire resistance, and low thermal and acoustic conductivity. Lightweight geopolymer concrete (LWGC) is an emerging type of concrete that is garnering attention in the construction industry for its sustainable and eco-friendly properties. LWGC is produced by using geopolymer binders instead of cement, thereby reducing the carbon footprint associated with conventional concrete production. However, the absence of standard codes for geopolymer concrete restricts its widespread application. To address this limitation, an investigation focused on developing a new mixture design for LWGC by modifying the existing ACI 211.2-98 provisions has been carried out. In this study, crucial parameters of LWGC such as alkaline/binder ratio, molarity, silicate/hydroxide ratio, and curing temperature were established using machine learning techniques. As a result, a simple and efficient method for determining the mix proportions for LWGC has been proposed.

Inconsistencies in standards and codes result in confusion, increased costs, and do not promote the efficient use of concrete. In addition to inconsistencies, the lack of science-based approaches and data used for defining criteria in these standards and codes can limit the reliability and trust of these requirements. A review of industry documents indicates that inconsistencies and lack of science-based approaches exist across many documents, both throughout the industry and within ACI, relating to the corrosion of steel reinforcement embedded in concrete. This paper proposes to address five key issues to promote science-based standardization of requirements necessary for reinforced concrete systems exposed to corrosive conditions. These five issues include the need for: 1) standardization of chloride testing methods and requirements; 2) standardization of chloride reporting units; 3) standardization of terminology for specifying chlorides in cementitious systems; 4) standardization of exposure classifications for corrosive conditions; and 5) standardization of allowable chloride limits. This paper presents current inconsistencies in guide documents and codes for each of the items listed previously and then proposes an approach to standardize each using either available data and/ or a scientifically based approach. Recommendations for testing, reporting, definition of exposure classifications, and allowable chloride limits are then proposed. It is hoped that the systematic approach used herein will lead to standardization and consistency, less confusion, and will promote the efficient use of durable and economical concrete.

Several incidents of early deterioration of structures have been reported in literature; such incidents have a negative impact. Insufficiencies in the durability design may result from a possible absence of explicit guidelines in design codes and standards that establish a standardized language for building design, construction, and operation. Most design codes and standards, while providing a robust framework for structural capacity and serviceability, do not address durability design to a desirable degree. This study examines and critically reviews the durability design in three international codes: the American, British, and Eurocodes. The study revealed that the European and British standards have comparatively more precise and comprehensive durability provisions, whereas the American code has a larger scope for development. The study introduces a proposal for the improvement of durability design provisions in codes to provide beneficial examples that can assist in the update of upcoming editions of these codes.

The overdesign of concrete mixtures and substandard concrete acceptance testing practices significantly impact the concrete industry’s role in sustainable construction. This study evaluates the impact of overdesign on the sustainability of concrete and embodied carbon emissions at the national and project scales. In addition, this paper reviews quality results from a concrete producer survey; established industry standards and their role in acceptance testing in the building codes; the reliance on proper acceptance testing by the licensed design professional, building code official, and the project owner; and the carbon footprints that result from overdesign of concrete mixtures. In 2020, a field survey conducted on over 100 projects documented Pennsylvania’s quality of field testing. Of those surveyed, only 15% of the projects met the testing criteria within the ASTM and building code requirements. As a result, the total overdesign-induced cement consumption is as large as 6.7% of the estimated cement used in the United States.

The use of industrial waste in concrete and controlled low-strength mixtures (CLSM) along with the experimental analysis of the fresh and hardened properties was investigated in this research. Four waste materials were used to design 17 mixtures. Fly ash and glass powder were investigated at high rates of replacement for cement, from 60 to 90%. This information is scarce in published literature and can help practitioners and concrete batchers in developing mixtures with a high level of replacement. Additionally, natural sand was substituted by glass sand which, in combination with fly ash and glass powder as cement replacement, provides an entirely new body of knowledge of concrete mixtures that use limited newly produced materials. Adequate strength and flowability was achieved with the use of recycled waste materials for both normal concrete and CLSM. All normal concrete mixtures except one, which had a 90% fly ash replacement, achieved a 28-day compressive strength of at least 29 MPa. Concrete with this compressive strength has multiple applications that represent a significant portion of the concrete produced. Using these mixtures has the potential to significantly reduce the amount of virgin products, especially cement that has a significant carbon footprint. All CLSM mixtures except two had a compressive strength of less than 2 MPa, therefore meeting the walkability and excavability requirements as set out in American Concrete Institute (ACI) guidelines and codes. Finally, an equation was proposed to predict the 28-day compressive strength of concrete with high volumes of fly ash replacement (>60%). As far as the authors are aware, there is no method to calculate the compressive strength of this type of concrete. This equation represents a significant contribution not only to the research body but also to practitioners and concrete batchers.