Said Jalali

Properties of tungsten mine waste geopolymeric binder

Abstract Tungsten mine waste mud (TMWM) geopolymeric binder is a new cementitious material with a very high early age strength. It is obtained from dehydroxylated mine waste powder mix with minor quantities of calcium hydroxide and activated with NaOH and waterglass solutions. Tests on properties of TMWM binders such as workability, setting time, unrestrained shrinkage, water absorption and static modulus of elasticity were carried out and the results are reported in this paper. This is followed by comparisons with literature related data and a discussion about it. The results showed that current devices use to assess OPC fresh properties are not recommended to evaluate TMWM binders. It has also been found that traditional procedures used to evaluate unrestrained shrinkage may be responsible for misleading results when using those new binders. Water absorption data shows that TMWM has a very compacted structure. Results concerning the static modulus of elasticity are similar to the ones obtained by other authors. However the hypothesis related to modulus of elasticity decrease due to the use of high Al/Si alkali activated mixtures was not confirmed.

Eco-efficient concrete

Part 1 Eco-efficiency of Portland cement concrete: Environmental impact of Portland cement production Low binder intensity eco-efficient concretes Life cycle assessment (LCA) aspects of concrete. Part 2 Concrete with supplementary cementitious materials (SCMs): Natural pozzolans in eco-efficient concrete Artificial pozzolans in eco-efficient concrete Tests to evaluate pozzolanic activity in eco-efficient concrete Properties of concrete with high volume pozzolans Influence of supplementary cementitious materials (SCMs) on concrete durability Performance of self- compacting concrete (SCC) with high volume SCMs High volume ground granulated blast furnace slag (GGBFS) concrete Recycled glass concrete. Part 3 Concrete with non-reactive wastes: Municipal solid waste incinerator (MSWI) concrete Concrete with polymeric wastes Concrete with construction and demolition wastes (CDW) An eco-efficient approach to concrete carbonation Concrete with polymers. Part 4 Future alternative binders and use of nano and biotech: Alkali-activated based concrete Sulfoaluminate cement Reactive magnesia cement Nanotechnology for eco-efficient concrete Biotechconcrete: An innovative approach for concrete with enhanced durability.

Toxicity of building materials: a key issue in sustainable construction

To avoid the use of toxic building materials is one of the principles of sustainable construction. However and contrary to general beliefs, current residential buildings frequently contain many toxic building materials, some of which even comply with legal regulations. Part of the problem is because architects and civil engineers have no form of knowing the toxicity of building materials. The other part is economically related. Some regulations about toxicity limits are influenced by economic reasons. For instance, although scientific evidence about the toxicity of lead plumbing has existed for quite some time, legal regulations avoid imposing very tight thresholds because of the cost of lead pipe substitution (in Europe that could cost almost 200,000 million euros). It is then no surprise to see that the related Directive (98/83/CE) established a 15-year delay period before the 10 μg/l lead content threshold is enforced. This paper discusses some cases of toxic building materials by reviewing previously published work, it also covers the emission of volatile organic compounds from paints and varnishes, the toxicity of impregnating agents, materials that release toxic fumes during a fire, asbestos-based materials, radioactive materials and lead plumbing.

Utilization of mining wastes to produce geopolymer binders

Abstract: This chapter discusses the utilization of mining wastes to produce geopolymeric binders. It includes the influence of calcination operations in the reactivity of mine wastes; in what way mix design parameters influence strength gain; it covers physical and mechanical properties and also durability and environmental performance.

New Eco-Friendly Gypsum Materials for Civil Construction

The sustainable world’s economic growth and people’s life improvement greatly depend on the use of alternative products in the architecture and construction, such as industrial wastes conventionally called “green materials”. This paper concerns the main results of an experimental work carried out with the objective of developing new composite materials based on gypsum and incorporating waste material as granulated cork, a by-product of cork industry, and cellulose fibres, a waste of paper industry. Such materials are intended to be used as composite boards for non structural elements of construction, such as dry walls and ceiling. Cork (bark of the plant Quercus Suber L), a substance largely produced in Portugal, is a material whose characteristics are of considerable interest for the construction industry. It is regarded as a strategic material with enormous potential by its reduced density, elasticity, compressibility, waterproof, vibration absorption, thermal and acoustic insulation efficiency [1]. During the first stage of this research work the gypsum binder and its properties were studied. Then, composites with mineral additions (added to increase the waterproofing and resistance) were also developed and submitted to tests to determine their physical and mechanical properties. In last stage, reinforced composites using different industrial by-products have been developed. This paper will present the properties and the manufacture methods used to produce the above mentioned eco-friendly composites that can ease ways for using industrial wastes as new construction materials, with excellent inherent thermal and acoustic properties.

Sustainable monitoring of concrete structures : strength and durability performance of polymer-modified self-sensing concrete

Concrete structures all over the world are reaching the end of their service life sooner than expected. This is due to the fact that ordinary Portland cement-based concrete deteriorates under environmental actions and also that structural inspections and conservation actions are expensive. Besides, as they consume energy and non-renewable resources, they have negative environmental impacts. Self-sensing concrete provides an alternative way of monitoring concrete-reinforced structures at a much lesser cost and with lesser environmental impact. Although the short-term mechanical properties of these materials are usually well documented, the long-term durability issues about carbon fibre concrete still deserve further investigations. This paper reports some investigation of the strength and durability characteristics of several concrete mixtures modified with different percentages of polymer and carbon fibre addition. The results show that the addition of carbon fibre decreases the strength and increases water penetration under pressure and also increases chloride diffusion, whereas polymer addition is responsible for a denser microstructure and higher concrete durability.

Application of braided fibre reinforced composite rods in concrete reinforcement

This paper describes the work that is being done at the University of Minho concerning the development of braided rods for concrete reinforcement. A preliminary research study has been conducted to understand the mechanical behaviour of braided fabrics. Various samples have been produced varying the type of fiber (glass, polyester and aramid), the type of braided fabric (simple, hybrid and core reinforced) and in the latter case, the number of core reinforcing yarns. The tensile properties of these samples have been evaluated and the results presented. The influence of each factor on the tensile properties of braided fabrics has also been analysed and discussed. In order to produce braided reinforced composite rods to use as a concrete reinforcement, a special technique has been developed using a standard vertical braiding machine. The braided reinforced composite materials have been produced in rib structure to improve adhesion between them and the concrete. Special samples have been prepared and tested to evaluate the adherence between both materials involved. The tensile and bending properties of braided reinforced composite rods have been evaluated and the results obtained presented and discussed.

Construction and Demolition (C&D) Wastes

This chapter includes the description of European waste catalogue codes related to C&D wastes highlighting those considered as hazardous wastes. It also includes the C&D wastes management plan which addresses the estimation of the several waste streams generated on-site. The selective demolition versus traditional demolition processes are analyzed. The principles and the benefits of design for disassembly are described. Considerations about waste sorting are made. This chapter also covers the recycling of gypsum materials, the inertization of C&D wastes containing asbestos and also the use of thermal treatments to produce concrete recycled aggregates with low cement paste content.

Self-monitoring Composite Rods for Sustainable Construction

This paper presents the development and properties assessment of braided reinforced composite rods (BCR) able to both reinforce and monitor the stress state of concrete infrastructures. The research study aims at understanding the tensile behaviour and self-monitoring ability of composite rods reinforced by a textile structure – braided structure with core reinforcement – for civil engineering applications, namely for concrete internal reinforcement, as a steel substitute, in order to improve structures safety and sustainability. Seven types of braided composite rods have been produced using an author patented technique based on a modified conventional braiding machine. The tensile properties of the braided reinforced composite rods were evaluated in order to identify the type(s) of fibre(s) to be used as core reinforcement. BCR have been tested under bending while the variation of the electrical resistance was simultaneously monitored.

Multifunctional Braided Composite Rods for Civil Engineering Applications

This paper presents the development of a braided reinforced composite rod (BCR) able to both reinforce and monitor the stress state of concrete elements. Carbon fibers have been used as sensing and reinforcing material along with glass fiber. Various composites rods have been produced using an author patented technique based on a modified conventional braiding machine. The materials investigated were prepared with different carbon fiber content as follows: BCR2 (77% glass/23% carbon fiber), BCR3 (53% glass/47% carbon fiber), BCR4 (100% carbon fiber). BCRs have been tested under bending while the variation of the electrical resistance was simultaneously monitored. The correlations obtained between deformation and electrical resistance show the suitability of the rods to be used as sensors. The fractional resistance change versus strain plots show that the gage factor increases with decreasing carbon fiber content.