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Construction of affordable housing in Malaysia has been one of the national objectives set by its government, ensuring low-income families have access to adequate housing. This paper discusses the perceptions and the needs of residents for the development of single-family housing units for low-income families in Kuala Lumpur, Malaysia based on the outcomes from participatory design activities in the city. As part of these activities, a series of six focus groups and participatory design workshops were conducted in Kuala Lumpur. The findings from these interactive sessions are to be used in the development of proposals for new housing in the city built for low-income families, advocating for consideration of the views of the residents in the design process.

Fiber reinforced polymer (FRP) composite materials have been used in a variety of civil and infrastructure applications since the early1980s, including in wind turbine blades. The world is now confronting the problem of how to dispose of decommissioned blades in an environmentally sustainable manner. One proposed solution is to repurpose the blades for use in new structures. One promising repurposing application is in pedestrian and cycle bridges. This paper reports on the characterization of a 13.4-m long FRP wind blade manufactured by LM Windpower (Kolding, Demark) in 1994. Two blades of this type were used as girders for a pedestrian bridge on a greenway (walking and biking trail) in Cork, Ireland. The as-received geometric, material, and structural properties of the 27 year-old blade were obtained for use in the structural design of the bridge. The material tests included physical (volume fraction and laminate architecture) and mechanical (tension and compression) tests at multiple locations. Full-scale flexural testing of a 4-m long section of the blade between 7 and 11 m from the root of the blade was performed to determine the load-deflection behavior, ultimate capacity, strain history, and failure modes when loaded to failure. Key details of the testing and the results are provided. The results of the testing revealed that the FRP material is still in excellent condition and that the blade has the strength and stiffness in flexure to serve as a girder for the bridge constructed.

This paper describes repurposing projects using decommissioned wind turbine blades in bridges conducted under a multinational research project entitled “Re-Wind”. Repurposing is defined by the Re-Wind Network as the re-engineering, redesigning, and remanufacturing of a wind blade that has reached the end of its life on a turbine and taken out of service and then reused as a load-bearing structural element in a new structure (e.g., bridge, transmission pole, sound barrier, seawall, shelter). The issue of end-of-life of wind turbine blades is becoming a significant sustainability concern for wind turbine manufacturers, many of whom have committed to the 2030 or 2040 sustainability goals that include zero-waste for their products. Repurposing is the most sustainable end-of-life solution for wind turbine blades from an environmental, economic, and social perspective. The Network has designed and constructed two full-size pedestrian/cycle bridges—one on a greenway in Cork, Ireland and the other in a quarry in Draperstown, Northern Ireland, UK. The paper describes the design, testing, and construction of the two bridges and provides cost data for the bridges. Two additional bridges that are currently being designed for construction in Atlanta, GA, USA are also described. The paper also presents a step-by-step procedure for designing and building civil structures using decommissioned wind turbine blades. The steps are: project planning and funding, blade sourcing, blade geometric characterization, material testing, structural testing, designing, cost estimating, and construction.

Cracking occurrence due to shrinkage related effects is a widely recognised issue which is frequently evaluated with the shrinkage restraining ring test. This paper provides a state-of-the-art review of the ring test method, which has been used for the last four decades. The last review on such matter was conducted only in early 2000s; however, a significant amount of studies has been conducted since then and considerable advancements or modifications in this testing method have taken place over the last decade. Studies on the traditional ring test, i.e. a circular concrete ring cast around a steel ring, are identified and the history, tendencies, practices and quantitative methods are analysed thoroughly. Furthermore, any modifications/advancements in the testing method with respect to their purpose, applications and capabilities based on current knowledge, are addressed. Finally, an insight on the challenges that the developers of testing methods for restrained shrinkage are faced with is given together with perspectives for their future potential improvement., This study was conducted during the “Short-term Scientific Mission” (STSM) fund awarded to the first author and hosted by the second author. The authors are grateful for the financial support received by COST Action TU1404 “Towards the next generation of standards for service life of cement-based materials and structures”. This work was partially financially supported by project POCI-01-0145-FEDER007633 (ISISE), funded by FEDER funds through COMPETE2020 - Programa Operacional Competitividade e Internacionalização (POCI), and by national funds through FCT - Fundação para a Ciência e a Tecnologia. FCT and FEDER (COMPETE2020) are also acknowledged for the funding of the research project IntegraCrete PTDC/ECM-EST/ 1056/2014 (POCI-01-0145-FEDER-016841). The contents of this paper reflect the views of the authors, who are responsible for the validity and accuracy of presented data, and do not necessarily reflect the views of their affiliated organisations., info:eu-repo/semantics/publishedVersion

The EU Waste Framework Directive 2008/98/EC states that all member states should take all necessary measures in order to achieve at least 70% re-use, recycling or other recovery of non-hazardous Construction and Demolition Waste (CDW) by 2020. In response, the Horizon 2020 RE4 project consortium (REuse and REcycling of CDW materials and structures in energy efficient pREfabricated elements for building REfurbishment and construction) consisting of 12 research and industrial partners across Europe, plus a research partner from Taiwan, was set up. For its success, the approach of the Project was manifold, developing sorting technologies to first improve the quality of CDW-derived aggregate. Simultaneously, CDW streams were assessed for quality and novel applications developed for aggregate, timber and plastic waste in a variety of products including structural and non-structural elements. With all products considered, innovative building concepts have been designed in a bid to improve future reuse and recycling of the products by promoting prefabricated construction methods and modular design to ease future recycling and increase value of the construction industry. The developed technologies and products have been put to the test in different test sites in building a two-storey house containing at least 65% of CDW.

The early age compressive strength of concrete can, according to the fib Model Code, be estimated from its 28-day strength using an exponential function. This requires an “s” value which depends on the strength class of the cement. This has recently been extended to include supplementary cementitious materials (SCMs), or otherwise known as additions, by providing a way of determining an appropriate “s” value based, in addition to cement strength class, on the water/binder and SCM/binder ratio. The applicability of this relationship for four concrete grades (C30/37, C35/45, C50/60 and C60/75) with up to 70% ground granulated blast-furnace slag (GGBS) has been investigated and shown to be satisfactory. This increased confidence in its use for predicting the strength development of other curing regimes, i.e. adiabatically cured concrete cubes, using the maturity function in the fib Model Code. Predictions/estimates of the effect of the adiabatic temperature history on the compressive strength development using the maturity function in the fib Model Code have been compared to those of the Arrhenius function that uses a strength-time relationship and “apparent” activation energy determined from experimental data. The fib Model Code’s strength estimates were not significantly affected by the use of one value of “apparent” activation energy for all concrete mixes, i.e. the “apparent” activation energy was not specific to the concrete mix.

The Modified Nurse-Saul function relies on (a) a relationship between concrete compressive strength and the Nurse-Saul maturity index, (b) an “acceleration” factor and (c) a “temperature efficiency” factor. The “acceleration” compresses a certain percentage of hydration or strength development into a smaller time interval. The strength development rate is therefore increased because of the “compression” of the hydration interval. Had the hydration at higher curing temperatures been as efficient in contributing to the compressive strength as at lower temperatures then the “acceleration” factor would be equal to the “compression” factor. Procedures are described to determine these factors from isothermally cured concretes. They are then used in an iterative procedure to predict/estimate the strength development for adiabatically cured concretes. The predictions/estimates are shown to be significantly more accurate than those from the Nurse-Saul and Arrhenius maturity functions.

Ground granulated blast furnace slag (GGBS) is the most common industrial by-product used as a precursor for alkali activated binders due to its fast setting, simple curing needs, and good early age strength gain. There are conflicting findings on the chloride penetration resistance of such binders and more information is required regarding the suitability of this type of binder material for chloride environments. This article outlines the findings of investigation of alkali activated slag concretes (AASC), to provide a comprehensive view of the effect of mix design variables on slump, strength, and chloride transport and binding. It is concluded that AASC can be designed for different workability and different grades of concrete. The diffusivity results demonstrate that the addition of excess water does not directly control the pore structure/connectivity in AASC as it does for Portland cement, and therefore AASC can be designed based on the water/binder ratio needed for a specified mechanical performance. The chloride binding capacity increased as the paste content of the concrete and/or the silica content of the activator was increased.

Geopolymer and Alkali-Activated Binders (AAB) has recently emerged as a new, green material with the potential to replace Portland cement in several applications. They can reduce the CO2 footprint of concrete by up to 80% and this is in addition to being more durable in certain aggressive environments. However, commercial alkaline activators contribute significantly to the cost and CO2 footprint of AAB concrete mixes. This research investigated the production of a low cost, low environmental impact sodium silicate solution (waterglass) from Rice Husk Ash (RHA) and more specifically RHA from Vietnam. A hydrothermal process for the dissolution of RHA in sodium hydroxide solution was developed. Sodium hydroxide solution concentration, process temperature and duration were studied. Optimised procedure parameters were found to be: NaOH concentration 3M, heating temperature 80 °C and heating duration 3 h. The obtained solution was used for the production of AAB mortar made with a blend of fly ash and ground granulated blast furnace slag. Obtained compressive strength of mortar was in the range of 60 MPa at 28 days, matching the strength obtained from control samples produced with commercially available activators. Microstructural investigation (isothermal calorimetry, infrared spectroscopy, X-ray diffraction and thermogravimetric analysis) on pastes confirmed the equivalence between the solution produced with the optimised method and commercially available options. Cost analysis indicated that the proposed method could allow a reduction of almost 55% of the cost for the activation of AAB. Results from a simplified preliminary environmental analysis suggested increased sustainability of the RHA-derived solution when compared with commercially available waterglass.

Geopolymer (GP) binders are an appealing alternative to Portland cement (PC) binders as they have the potential to reduce the CO2 emissions associated with the cement and concrete industry. However, their durability in aggressive environments needs thorough examination if they are to become a viable alternative to traditional PC materials. This study investigated the effect of increasing slag content and activator dosage on the sulfuric acid resistance of fly ash GP binders. Their performance was also compared with that of neat PC mixes using various physical and microstructural techniques. The results show that increasing the slag content of fly ash GPs decreases porosity, but makes the reaction products more susceptible to sulfuric acid attack. It was also found that increasing the alkaline activator dosage of fly ash GPs has little impact on sulfuric acid resistance. Finally, GP binders displayed superior sulfuric acid resistance than their PC counterparts.

There is often a demand in developing countries for single-storey buildings, for industrial and agricultural use. Whilst conventional hot-rolled steel sections are still commonly used for the primary column and rafter members, for frames of modest span (up to 30 m), a viable alternative can be the use cold-formed steel sections. Advantages include pre-galvanised sections that do not require painting to prevent rusting; reduced transportation and acquisition costs as the cold-formed steel used for the secondary members can come from the same supplier; bolted joints that are easy to assemble on site. This paper compares both types of portal steel buildings in terms of a life-cycle assessment (LCA) and a life-cycle cost (LCC). Three sizes of buildings are considered: 18 m, 24 m and 30 m. It is shown that in terms of the primary framing, use of cold-formed steel for the 18 m and 24 m span buildings can result in up to 30% less embodied carbon than hot-rolled steel. However, when secondary members and cladding are taken into account in the LCA, the differences in embodied carbon of cold-formed and hot-rolled steel are found to be negligible. LCC is concerned not only with the cost of the steel, but also with the labour costs and the cost of having a crane on site. It is shown that the 18 m and 30 m span cold-formed steel frames are cheaper than the hot-rolled steel frames by 33% and 15%, respectively, primarily owing to the fact that the erection of cold-formed steel portal frames have less demand for having a crane onsite. The use of LCA and LCC has therefore helped quantify associated embodied carbon and costs, with differences between section types for the primary framing shown to be relatively negligible when considered in context of the entire building, and the real differences between the two types of steel due to the ease of erection on site.

To get an insight into the radiological features of potentially reusable by-products in the construction industry a review of the reported scientific data is necessary. This study is based on the continuously growing database of the By-BM (H2020-MSCA-IF-2015) project (By-products for Building Materials). Selection criteria were defined for manual data mining in such a way to avoid the collection of too heterogeneous datasets. Currently, the By-BM database contains individual data of about 431 by-products and 1095 construction and raw materials. The By-BM database only consists out of measurement information on individual samples and not out of processed data that only gives a rough summary (such as only a range or average) of experimental results. As a consequence of the statistical analysis of the data, it was found that in the case of the construction materials the natural isotope content had a wider distribution than the by-products. However, the average of the Ra-226, Th-232 and K-40 contents of reported by-products were 2.00, 2.11 and 0.48, while the median was found 1.97, 1.24 and 0.53 times higher than the construction materials, respectively. The calculated Radium equivalent concertation was greater than the accepted value for residential properties of 370 Bq/kg in the event of 10.3% of total construction materials and 42.4% of by-products, while the I-indexes were above 1.0 index value with 17.3% and 58.2%, respectively. From the obtained data, it can be concluded that the reuse of industrial by-products in construction materials for residential purposes, without due diligence, can pose elevated risks to residents as a result of their high-volume usage. (C) 2017 Elsevier Ltd. All rights reserved. The project leading to this application has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 701932. R. Doherty's time was also supported by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 643087. The authors would also like to acknowledge networking support by the COST Action TU1301. www.norm4building.org.

The effects of paste volume, water content and precursor blend on consistency, setting time and compressive strength of alkali activated concrete (AAC) produced with fly ash (FA) and ground granulated blast furnace slag (GGBS) have been investigated with the aim of developing a suitable mix design procedure. Paste volumes in the range 30–33% were found not to influence the compressive strength but did influence the consistency of the mixes. The water-to-solid ratio was found to influence compressive strength and setting time. Increasing GGBS content in the binder blend resulted in an increase of the compressive strength, but higher GGBS content caused also early setting which may be undesirable. A mix design procedure has been developed and has been used to determine the constituent mix proportions for three classes of concretes, i.e. (a) a ready-mix concrete with nominal strength 35 MPa, (b) a typical structural concrete with nominal strength 50 MPa, and (c) a high strength concrete for precast applications with nominal strength 70 MPa. Cost analysis was carried out to compare the AAC with Portland cement concretes with similar properties. Normal strength Portland cement concrete (PC), as typically used in ready mix industry has been shown to be less expensive than AAC. However, alkali activated concrete can be competitively priced for high strength concretes. An empirical step-by-step procedure is presented for selecting trial mix proportions for concretes with a range of consistency values, setting times and cube compressive strengths.

Traditional Portland cement (PC) concrete has been used for many years in the agricultural industry for the construction of silos and silage effluent storage facilities. However, the acidic nature of the silage effluent produced by silage has led to severe degradation of PC concrete which in turn has significant environmental and financial implications. This study compares the resistance of PC and geopolymer (GP) mortars and pastes to silage effluent over 12 months. The GP samples displayed increased resistance to silage effluent in terms of mass and strength loss. Analysis of microstructure suggests that the increased stability of the reaction products is the main factor behind increased silage effluent resistance when compared with PC. It was also found that blends of pulverised fuel ash (PFA) and ground granulated blast furnace slag (GGBS) with a higher PFA content may offer increased long term silage effluent resistance due to the nature of the main binder gel produced in PFA dominant systems.

Cement masonry units are not considered as sustainable due to consumption of fuel, cement and natural resources and embracing alternatives is mandatory. Geopolymer is a green cementitious material and has excellent mechanical properties, consumes low energy in production and emits less carbon dioxide. The effects of paste volume, proportion of alkaline activator and water/solid ratio were investigated to develop self-standing dry mix of geopolymer hollow block and compared with OPC mix. Factors that require attention in casting geopolymer dry mix are discussed in this article. The optimized mix of geopolymer self-standing dry mix is expected to be found between 30 and 35% of geopolymer paste volume for 7.5% of alkaline dosage and alkaline molar ratio of 1.00.

Geopolymers produced by using waste materials are more cost-effective and environmentally friendly. Commercial sodium silicate (sodium water glass) is currently being produced by direct fusion of pure silica sand and soda ash (Na2CO3) in oil, gas or electrically-fired furnaces at high temperatures (~1300 °C)—a production process that is energy intensive and which generates CO2. One method of minimizing these environmental issues is to use supplementary sources of silica, such as rice husk ash (RHA), to produce sodium silicate at lower temperatures. Therefore, this project aims to compare the effect of sodium silicate solution made of rice husk ash sieved at various particle sizes (un-sieved

Neat fly ash-based alkali activated binders require high activator dosages and high temperature curing in order to develop satisfactory mechanical properties. Blending ground granulated blast furnace slag (GGBS) with fly ash can give medium to high strengths without the need for high temperature oven curing. An extensive investigation was carried out for understanding the effects of GGBS substitution of fly ash in mortar. GGBS substitution in the mix has an impact on mix proportions, fresh and hardened properties, and microstructure of reaction products. The strength of fly ash/GGBS blends cured at room temperature increased with the increase of GGBS content, whilst setting time showed an opposite trend. Fly ash/GGBS blends required lower activator dosages for obtaining high compressive strength, which has cost and environmental benefits. XRD, FTIR, TGA, and SEM/EDX results confirmed the presence of C-A-S-H gel as a reaction product with as low as 20% GGBS content.

The strength development of standard and adiabatically cured concretes was determined. The concrete mixes were of 28-day cube strengths of 50 and 30 MPa and also had Portland cement (PC) replaced partially with fly ash (FA) and ground granulated blast-furnace slag (GGBS) at 30% and 50%, respectively. The peak adiabatic temperature was effectively reduced with GGBS addition but was only reduced with FA addition for the lower w/b concrete. Considerable early age strength enhancements resulted from the adiabatic curing regime. The Nurse-Saul and Arrhenius based maturity functions were used to estimate the increases in early age adiabatic strength. The Nurse-Saul function underestimated the effect of high early age curing temperature for all concretes but to a greater extent for those with GGBS and FA whilst the Arrhenius based, which allows for the consideration of an “apparent” activation energy, gave more accurate estimates. Strength estimates for adiabatically cured concretes and isothermally (50 °C) cured mortars were also compared indicating that the latter might have been affected by the detrimental effect of high curing temperatures starting from early age.

This study characterises the naturally occurring radionuclide (NOR) contents of a suite of secondary raw materials or industrial residues that are normally disposed of in landfills or lagoons but now are increasingly used in green concretes. This includes ashes from a variety of industrial processes and red mud from aluminium production, as well as air pollution control residue and cement kiln dust. The chemical composition of the samples was determined with X-ray fluorescence spectroscopy (XRF). The Ra-226, Th-232 and K-40 activity concentrations were obtained by gamma spectrometry, and the results were compared with recently published NOR databases. The correlation between the NOR contents and the main chemical composition was investigated. The radioactive equilibrium in the U-238 chain was studied based on the determination of progeny isotopes. The most commonly used calculation methods (activity concentration index and radium equivalent concentration) were applied to classify the samples. The radon exhalation rate of the samples was measured, and the radon emanation coefficient was calculated. Significant correlation was found between the NORs and certain chemical components. The massic exhalation demonstrated a broad range, and it was found that the emanation coefficients were significantly lower in the case of the residues generated as a result of high-temperature combustion processes. The results showed a weak correlation between the Ra-226 concentration and the radon exhalation. This emphasises that managing the Ra-226 content of recycled material by itself is not sufficient to control the radon exhalation of recycled materials used in building products. The investigated parameters and their correlation behaviour could be used to source apportion materials found during the process of landfill mining and recovery of material for recycling. The project leading to this paper has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 701932. R. Doherty's time was also supported by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 643087. The authors would also like to acknowledge networking support by the COST Action TU1301 (www.norm4building.org).

A simple process to produce sodium silicate powder from glass cullet has been developed. A mixture of glass powder, sodium hydroxide powder, and water was heated at temperatures of 150 to 330 °C. The effects of glass to NaOH ratio, temperature and duration, inclusion of water and fineness of NaOH were investigated. Fly ash and fly ash/GGBS blends were the precursors for alkali activated binder (AAB) mortars produced with this sodium silicate. Compressive strengths were similar to or better than those obtained with commercially available sodium silicate and sodium hydroxide solutions. FT-IR tests suggested that the reactivity of the glass derived sodium silicate powder was related to the number of non-bridging oxygen atoms in the silicate structure. Cost comparison between AAB and Portland cement concretes gave similar results for normal strength concretes (35 MPa). AAB concretes with higher strengths (50 and 70 MPa) can be cheaper than equivalent traditional concrete.

Construction and Demolition Waste (CDW) accounts for approximately 25-30% of all waste generated across Europe each year. However, Waste Framework Directive 2008/98/EC requires from all EU member states to achieve at least 70% re-use, recycling or other recovery of non-hazardous CDW by 2020. In response, the Horizon 2020 RE4 Project (REuse and REcycling of CDW materials and structures in energy efficient pREfabricated elements for building REfurbishment and construction) consortium was set up. Its main aims are to assess the quality of various CDW fractions (e.g. mineral aggregate, timber, plastics, silt & clay), improve the quality of mineral aggregates and develop different building elements/components which contain at least 65% of CDW. Innovative building concepts will also be developed in an effort to improve recycling rates of future buildings through the use of prefabrication and modular design. The developed products and technologies will be assessed in a number of test sites by building 2-storey demonstration houses.

Mine tailings disposal is an increasingly important issue for mining companies. Two recent tailing dam failures in Brazil have caused unmeasurable environmental, social and economic damages. This study evaluated the use of iron ore tailings (IOT) as a source of silica (SiO2) to produce an alternative form of sodium silicate (SS) for use as an activator in one-part geopolymer binders. The novel SS was produced in a mechano-thermo-chemical process for mixing IOT with sodium hydroxide (NaOH). The materials were characterised by mineral composition, mineral phase, chemical groups and morphology. One-part geopolymer binders were synthesised with commercial SS and SS produced from tailings to compare their reactivity. Compressive strength tests showed that geopolymers produced with tailings SS and commercial SS achieved maximum mechanical resistance values of approximately 32 MPa and 40 MPa, respectively, which are comparable to regular Portland cement.

The effect of elevated curing temperature on the strength development of concrete mixes with fly ash (FA) has been investigated for strength grades C32/40 and C55/67. Percentages of fly ash in the total binder were 15, 30 and 45 per cent. High curing temperatures have a beneficial effect on the early age strength but a detrimental effect on the long-term strength development. Fly ash concrete mixes have been shown to be less sensitive to curing at high temperatures than Portland cement (PC) concretes and this was reflected in their lower “apparent” activation energies. The accuracy of strength estimates obtained from maturity functions was examined. The temperature dependence of the Nurse-Saul function, i.e. the concrete strength gain rate varies linearly with temperature, was not sufficient to account for the improvement in early age strengths resulting from high curing temperatures. The Arrhenius based function, on the other hand, overestimated them because of the detrimental effect of high curing temperature on strength starting from a very early age. Both functions overestimate long term strengths as neither accounts for the detrimental effect of high curing temperatures on the ultimate compressive strength.

Several factors affecting the reactivity of pulverised fuel ash (pfa) as a precursor for geopolymer concrete have been investigated. These include physical and chemical properties of various pfa sources, inclusion of ground granulated blast furnace slag (ggbs), chemical activator dosages and curing temperature. Alkali-activated pfa was found to require elevated curing temperatures and high alkali concentrations. A mixture of sodium hydroxide and sodium silicate was used and this was shown to result in high strengths, as high as 70 MPa at 28-days. The presence of silicates in solution was found to be a key factor. Detailed physical and chemical characterisation was carried out on thirteen pfa sources from the UK. The most important factor affecting the reactivity was found to be the particle size of pfa. The loss on ignition (LOI) and the amorphous content are also important parameters that need to be considered for the selection of pfa for use in geopolymer concrete. The partial replacement of pfa by ground granulated blast furnace slag (ggbs) was found to be beneficial in not only avoiding the need for elevated curing temperatures but also in improving compressive strengths. Microstructural characterisation with scanning electron microscope (SEM) coupled with energy dispersive X-ray spectroscopy (EDS) was performed on pfa/ggbs pastes. The reaction product of pfa and ggbs in these binary systems was calcium aluminium silicate hydrate gel (C-A-S-H) with inclusion of Na in the structure.

There have been considerable developments in Merseyside over the last fifteen years with regards to the commercialisation of recycled demolition aggregate. Liverpool is an urban region that at the time was undergoing regeneration. This required the demolition of old infrastructure. Subsequent reconstruction required new construction materials. A project started in 2001 to investigate the economics, practicalities and technicalities of using recycled demolition aggregates in concrete precast products. It was estimated that if all six demolition contractors around Liverpool worked round the clock (i.e. assuming there was enough feed material) they would still have found it difficult to maintain the required supplies for a single precast factory. Investment in equipment was therefore required to guarantee supply and improve the quality of the recycled demolition aggregate. The market forces and the incentives/drivers for construction companies to adopt sustainable practises have encouraged investment of several million pounds to be made in new recycling plants and has resulted in ‘urban quarries’. This paper describes the developments in recycling of construction and demolition waste over the last decade in Merseyside and shows that recycling is not only sustainable but also profitable.

This work focuses on low-purity kaolin, widely accessible throughout the globe. Room temperature cured geopolymer mortars (GPMs) were formulated using an aluminosilicate precursor based on calcined lithomarge and potassium silicate activator. The effect of mix proportion parameters on the engineering properties of GPMs was investigated. The behaviour of GPMs was compared with that of Portland cement-based mortars (PCMs). Statistically designed experiments revealed that an increase in water-to-solid (w/s) ratio had a dominant effect on increasing the workability and setting time while decreasing the compressive strength of GPMs. In contrast to PCMs, GPMs proportioned with a constant water content showed a non-linear relationship between the w/s ratio and workability, which could be associated with changes to paste/sand proportions and/or water/alkali proportions. Like-for-like comparison of GPMs and PCMs showed that GPMs require lower free water content, and can offer shorter setting times and a rapid strength development.

Poor storage of industrial wastes has been a cause of land contamination issues. These wastes or by-products have the potential to be used as secondary raw materials in construction, promoting the concept of a circular economy that will avoid land contamination. Here we evaluate radiological environmental impacts when wastes that contain elevated levels of naturally occurring radionuclides (NORs) such as red mud, fly ash and ground granulated blast furnace slag are made into ‘green cements’ such as geopolymers or alkali-activated materials (AAMs). During the study, three AAM concrete and mortar series with various mixing ratios were prepared and investigated. The NOR content, I-Index, radon emanation and exhalation of the precursor waste materials and their cement products were measured and calculated and the strength of the cement products was compared. The emanation and the exhalation properties were calculated for the final products, weighing the data of the components as a function of their mixing ratio. The I-index alone suggested that the AAMs would be suitable products. AAMs containing ground granulated blast furnace slag exhibited the lowest radon exhalation and higher compressive strength, while the fly ash and red mud AAMs had increased final radon exhalation. In the case of fly ash, alkaline activation of fly ash dramatically increased the radon exhalation; the highest measured fly ash exhalation was 1.49 times of the theoretically calculated exhalation value. This highlights the increased risk of using fly ash as a component in AAMs and the need to carry out testing on the final products as well as individual secondary raw materials. The project leading to this paper has received funding from the The project leading to this paper has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no 701932. R. Doherty's time was also supported by the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 643087. Sklodowska-Curie grant agreement no. 643087.

The resistance of room temperature cured geopolymer mortars (GPM) against chemical attacks, i.e. sodium and magnesium sulfate solutions, and sulfuric and hydrochloric acid solutions, was evaluated. GPMs were formulated using a lithomarge precursor (low-purity kaolin) to achieve 28-day characteristic compressive strengths of 37.5 and 60 MPa. Their performance was compared with those of equivalent Portland cement mortars (PCMs) having the same paste volume and strength grade. GPMs with both strength grades showed superior performance against sulfate attack when compared to PCMs. No visual deterioration was observed in GPMs, the mass and length changes were relatively small, and no changes to the microstructure were detected – in contrast to severely deteriorated PCMs. As confirmed by visual observations and lower mass loss, GPMs showed better resistance to attack by both acids than PCMs. GPMs provided a better quality (lower permeability) of an acid-degraded layer, lowering the degree of further deterioration. The main mechanisms of the matrix deterioration of GPMs in both acids was dealumination of the hardened binder, with a higher degree of changes detected for sulfuric acid.

This paper is the joint work of working group 4 of the RILEM TC 238-SCM and the fib Task Group 4.6. It was the aim of this literature study to quantify the effect of ground granulated blast furnace slag (GGBS) and silicious fly ash (sFA) on strength development of concrete. For the strength development the approach of the fib Model Code was chosen, which is based on an e-function that can be adapted to the strength development of an individual binder by selecting the so-called s-value based on the strength class of the Portland cement used. No guidance is provided for s-values for supplementary cementitious materials (SCMs). In order to determine the s-values for mixes with SCMs, a database was set up with results of material testing from literature. A relationship between s-values and w/b plus SCM/b ratios has been determined. This has been tested on laboratory cast specimens with 50 and 30% cement replacement with GGBS and FA respectively. These were cured at 20 °C. The s-values from this relationship were compared to those obtained from regression analysis and they were found to be satisfactory. This increased confidence in their use for predicting the strength development of other curing regimes, i.e. adiabatically cured concrete cubes, using the maturity function in the fib Model Code. Predictions of the effect of curing temperature, i.e. the adiabatic temperature history, on the strength development were again satisfactory. These were not significantly affected by the fib model code’s use of one value of “apparent” activation energy.

International audience; Since the discovery of the latent hydraulic reactivity of ground granulated blast-furnace slag (ggbfs) by Emil Langen at the end of the 19th century, this material has been used successfully as cement and concrete addition. This chapter includes all relevant information about this valuable material—from production and processing to the effect, which ggbfs additions have on the concrete performance. In this context, light is shed on decisive performance parameters of ggbfs. Of special interest nowadays is certainly also the information given about trace element contents in ggbfs and their leachability. Here and throughout the entire chapter, the latest insights from research and development work are included. Last but not least, the chapter contains very practical information when it comes to the use of ggbfs in concrete, including insights on rheological effects, concrete color and “greening”, and adequate curing. Moreover, an overview about relevant norms and standards on ggbfs as concrete addition is given. © RILEM 2018.

The growth of the construction industry worldwide poses a serious concern on the sustainability of the building material production chain, mainly due to the carbon emissions related to the production of Portland cement. On the other hand, valuable materials from waste streams, particularly from the metallurgical industry, are not used at their full potential. Alkali-activated concrete (AAC) has emerged in the last years as a promising alternative to traditional Portland cement-based concrete for some applications. However, despite showing remarkable strength and durability potential, its utilisation is not widespread, mainly due to the lack of broadly accepted standards for the selection of suitable mix recipes fulfilling design requirements, in particular workability, setting time and strength. In this paper, a contribution towards the design development of AAC synthesised from pulverised fuel ash (60 %) and ground granulated blast furnace slag (ggbs) (40 %) activated with a solution of sodium hydroxide and sodium silicate is proposed. Results from a first batch of mixes indicated that water content influences the setting time and that paste content is a key parameter for controlling strength development and workability. The investigation indicated that, for the given raw materials and activator compositions, a minimum water-to-solid (w/s) ratio of 0.37 was needed for an initial setting time of about 1 h. Further work with paste content in the range of 30–33 % determined the relationship between workability and strength development and w/s ratio and paste content. Strengths in the range of 50–60 MPa were achieved.

Geopolymer binders are generally formed by reacting powdered aluminosilicate precursors with alkali silicate activators. Most research to date has concentrated on using either pulverised fuel ash or high purity dehydroxylated kaolin (metakaolin) in association with ground granulated blast furnace slag as the main precursor material. However, recently, attention has turned to alternative calcined clays that are abundant throughout the globe and have lower kaolinite contents than commercially available metakaolins. Due to the lack of clear and simple screening protocols enabling assessment of such geological resources for use as precursors in geopolymer systems, the present paper presents results from experimental work that was carried out to develop a functional binder using materials containing kaolinite taken from the Interbasaltic Formation of Northern Ireland. The influence of mineralogy has been examined, and a screening process, using three Interbasaltic materials as examples, that will assist in the...

Three mixes were provided namely normal weight self-compacting concrete with Portland cement as a control (NWSCC-PC), lightweight self-compacting concrete with ground granulated blast furnace slag concrete (LWSCC-GGBS) and lightweight self-compacting concrete with limestone powder concrete (LWSCC-LSP). There were three cubes of each mix for each testing age, which were cured at 20, 30, 40 and 50 °C to investigate the effect of curing temperature on strength development. They were tested at ages 0.125, 0.25, 0.5, 1, 2, 4, 7, 14 and 28 days. The results showed that the strength development of self compacting concrete strongly affected by curing temperature as it does with normal concrete. At early ages, the strengths development of concrete cured at higher curing temperature, were faster than that of concrete cured at lower temperature. The strength development of concretes cured at lower temperature, however, have higher strength at later ages.

This chapter briefly discusses some alternatives to Portland cement. These include calcium aluminate cement (CAC) that has been in use for a hundred years or so and some cements that have more limited use and/or are currently being developed and are not yet in widespread use. This latter group is of particular interest because of their potential of being produced at lower temperatures than Portland cement, thereby requiring less energy for production; this is a major concern for Portland cement in relation to sustainability issues, particularly carbon emissions. The setting time of CAC is about 30 minutes longer than that of a typical Portland cement. There are, however, several current important uses of CAC and concrete that takes advantage of its superior properties compared to other cements: alkali-activated cements, geopolymer cements, waste-derived cements and magnesium oxide-based cements.