Eshmaiel Ganjian

Effect of Steel Slag and Portland Cement in the Rate of Hydration and Strength of Blast Furnace Slag Pastes

This paper presents an experimental study of the influence of steel basic oxygen slag (BOS) and ordinary portland cement (OPC) on the compressive strength and the hydration mechanisms of blended grounded granulated blast furnace slag (GGBS) pastes. The compressive strength, the mineralogical changes due to hydration, the setting times, the alkalinity of the raw materials, and the pore solution, and the volume stability were measured on binary and ternary mixes. It is concluded that the steel slag can be used as an activator of GGBS and the optimum composition of those materials was determined with a proposed parameter called “slag index.” The properties measured in blended OPC-GGBS-BOS mixes showed encouraging results to be used industrially. The mechanisms of hydration of the blended slag mixes are discussed and a hydration model of the blended system GGBS-BOS is proposed.

Potential for carbon dioxide reduction from cement industry through increased use of industrial pozzolans

Abstract Abstract Concrete is the most widely used material on earth, eclipsing the combined volumes of all other man made materials by a factor of ten. In terms of its embedded carbon, it is a benign product, being associated with relatively little CO2 per unit mass when compared with metals, glasses and polymers. Conversely, it is made in such vast quantities, that it is responsible for over five percent of anthropogenic CO2. Despite recent advances in kiln design and alternative, low energy clinkers, it seems likely that the greatest carbon savings from the industry are likely to be made by the inclusion of supplementary cementing materials. This article reviews some of the options currently under investigation, especially from the UK perspective, and highlights that some of the research needs to be satisfied before such materials are more widely adopted.

RECYCLED MATERIALS IN CONCRETE BARRIERS

Results are reported from a research program that investigated use of concrete containing leachate from landfill waste in barrier structures. The barriers were constructed of a composite multi-layer design with concrete above and below a clay core. The aim is to provide a financially attractive alternative to current technologies such as bentonite and high-density polyethylene membranes. A wide range of materials were tested for use in the concrete including slags, ashes, and other industrial byproducts. Many of the mixtures do not contain any constituents which have commercial value. Results indicate that the barriers are durable, but the concept of durability must be carefully understood within this context.

Implementation of total quality management in the Libyan construction industry

Delivering quality projects is a real challenge for the construction sector in Libya. However, there is little information for developing quality improvement initiatives in construction companies. The aim is to present the main factors influencing the implementation of quality management systems in Libyan construction industry (LCI) through a review of relevant literature, and identify the most important factors based on a survey of managers working in construction companies in Tripoli. Of 200 hundred questionnaires distributed, 130 were fully completed giving a response rate of 65%. Among these respondents, 63% were government-related organisations, and the rest were from private sector. The data were subjected to principal component analysis (PCA), which helps interpretation of data. The analysis identified five reliable and valid quality management constructs namely top management commitment, communication, teamwork, employee empowerment and involvement, and work environment and culture. These will help to focus areas for improving quality in construction projects.

An Empirical Investigation of Total Quality Management in Libya: A Proposed Guideline of Implementation

Rapid socio-economic and technological changes have urged the implementation of new approaches to procure construction projects. Total Quality Management (TQM) is one of the approaches that contribute towards ensuring that projects are being delivered to the stakeholder requirements. This study identifies critical success factors (CSFs) that affect the implementation of TQM in the Libyan Construction Industry (LCI) and develops guidelines which help companies implement and maintain quality management systems. To achieve these aims, the research employed both quantitative and qualitative methods. Based on a thorough review of literature, a questionnaire was developed and distributed to 200 managers. Data from 130 completed questionnaires were then analysed using Principal Component Analysis (PCA), which reveals the internal structure of the data in a way that explains the dimensions of TQM implementation in LCI. The results identify five reliable and valid TQM dimensions, namely organisation management, communication to improve quality, training and development, employee involvement and recognition, and culture. Supported by relevant literature and interviews with a number of managers, they provide the basis for developing the guideline for successful implementation of TQM in Libyan construction companies.

Zinc-Rich Paint As Anode for Cathodic Protection of Steel in Concrete

This paper describes the findings of the experimental works undertaken to investigate the performance of zinc-rich paint (ZRP) to provide cathodic protection to chloride-contaminated reinforced concrete (RC) structures. The program of experimental works was designed and conducted to assess four principal properties, viz (1) conductivity, (2) adhesion with concrete (short term and long term), (3) durability, and (4) electrochemical polarization. These properties considered together define the ability and effectiveness of the materials to act as an anode for impressed current cathodic protection. The research findings indicated that a specific proprietary ZRP product showed that optimum conductance was obtained with three coats producing a 280-320 μm thickness, with good adhesion to the concrete substrate, in which values obtained ranged between 1.65 and 3.5 MPa with and without applied current. It was capable of withstanding/supporting high levels of current, i.e., more than 300 mA/m², and the service life of the ZRP coating was estimated to be well in excess of 20 years at an applied current density of 10 mA/m².

Reducing Cement Contents of Paving Blocks by Using Mineral Waste and by-Product Materials

AbstractIn the production of conventional paving blocks, it is usual to use a minimum of 210  kg/m3 of cement. However, when portland cement is produced, it impacts negatively on the environment due to carbon dioxide emissions. Therefore, this paper investigates the use of waste and by-product materials, such as run-of-station ash (ROSA), basic oxygen slag (BOS), ground granulated blast-furnace slag (GGBS), plasterboard gypsum (PG), and cement bypass dust (BPD) to reduce the amount of cement in paving blocks. The combinations of binary and ternary blends in different mixes are considered. Tensile strength, skid/slip and freeze/thaw resistance of paving blocks, verified that a cementitious mix containing ROSA up to 60%, GGBS up to 55%, BPD up to 25%, and plasterboard gypsum PG up to 5% by weight can replace portland cement without having any substantial impact on the strength or durability of the blocks. XRD and XRF tests of selected mixes have been presented and discussed. Concrete blocks prepared with OP...

Compressive Strength of Cement Mortar Using Sebha Clay, Treated by Sonication Method

Clay as natural pozzolan is found in the north of the city of Sebha, Libya. Sebha clay is relatively high in silica, and its physical and chemical properties could be referred to as ASTM C618 class N. Sonication treatment is carried out and the treated Sebha clay is used as a mineral admixture in the Portland cement mortar. Horn method 20 kHz frequencies with different powers and different times are used in the Sonication treated. The particle size distributions (PSD) and Scanning Electron Microscope (SEM) imaging are used to understand the mechanism of pozzolanic improvement of the Sebha clay after treatment by sonication. This paper shows the physical and chemical properties of sonication treat Sebha clay. The effect of magnitude of sonic power on pozzolanic activity of treated kaolin is investigated. The main aim of the present research is to study the strength characteristics of cement mortar using Sebha natural clay after sonication is treated as a partial replacement of ordinary Portland cement OPC. The parameters are investigated, including compressive strengths .The results show enhancement in particle size and pozzolanic activity of treated kaolin, with increase in sonic power and in the time.

Special Section on Sustainable Construction Materials

This special section of the ASCE Journal of Materials in Civil Engineering was put together at the suggestion of the editor in chief, Professor Antonio Nanni. These manuscripts were part of the Second International Conference on Sustainable Construction Materials and Technologies, which was held in Ancona, Italy, from June 27 to 30, 2010. About 250 papers were originally proposed for this conference. From these, 25 manuscripts were selected by the conference organizing committee. An international panel of experts was established for further selection of the manuscripts. After initially selecting 18 manuscripts, the panel evaluated the full manuscripts and selected 12 as being especially noteworthy for consideration by the Journal of Materials in Civil Engineering. The selected 12 manuscripts were reviewed by a minimum of three reviewers, following the established anonymous procedure for publication in ASCE journals. Following thorough review, 11 of the 12 manuscripts were accepted. After requested revisions were finished by the authors, the final manuscripts were accepted by the editors for publication in this volume. The editors of this volume are grateful to all reviewers for conducting their reviews in a timely and professional manner to bring this issue to publication.