Sustainable Masonry Research Articles

Water Treatment Sludge–Calcium Carbide Residue Geopolymers as Nonbearing Masonry Units

AbstractIn this research, water treatment sludge (WTS) calcium carbide residue (CCR) geopolymers were evaluated as a sustainable masonry nonbearing unit. The WTS was a by-product from a water treat...

Development of sustainable masonry units from flood mud soil: Strength and morphology investigations

In the aftermath of the mega flood 2014–2015 event on the East Coast of the Peninsular Malaysia high piles of debris and mud were found deposited on the affected area. The cost of cleaning and removal of the debris and mud was extremely high. Utilisation of the flood mud soil as an aggregate to develop sustainable masonry units could be possible through chemical stabilisation to increase the strength of the soil. Biomass silica (BS) stabiliser was used to enhance the engineering properties of the flood mud. The flood mud soil sample was taken from Kuala Krai, Kelantan, after the flood event, which occurred during December 2014 and January 2015. The Unconfined Compressive Strength (UCS) of unstabilised samples and samples stabilised using 3%, 5% and 10% stabiliser, was measured after three and seven days of curing. The stabiliser could increase the soil strength up to 10-fold (1330kPa) of the unstabilised strength but was still lower than the strength requirement specified by British Standard Institute. An addition of 2% of cooking salt at 105°C curing could significantly improve the UCS. Microstructural analyses via Energy-Dispersive X-ray spectrometry (EDX) and Field-Emission Scanning Electron Microscopy (FESEM) tests were undertaken to examine the influence of BS stabiliser, cooking salt and heat curing on UCS development. The additional cooking salt with heat curing caused the aggregation and enhanced the chemical reaction of the BS stabilised soil. The formation of Calcium Silicate Hydrate (CSH) and Calcium Aluminate Hydrate (CAH), as shown by white-coloured lumps, filled the pore spaces of the biomass silica stabilised soils. The aggregation and CSH and CAH products resulted in a dense and strong soil structure and subsequent strength development. This research indicates that the mixture of BS stabiliser and cooking salt can be used to manufacture mud-based masonry units as a sustainable construction and building material.

Development of stabilised brick and mortar using biomass waste

This paper reports the potential of using cereal ash and bottom ash waste generated from biomass combustion plants for the manufacture of stabilised bricks and sustainable masonry mortar for brick joints and plaster. For the stabilised brick production, the cereal ash waste and bottom ash waste were used as full substitutes for primary clay, while magnesium oxide ash was used as a partial substitute for conventional stabilisers. The blending for the production of the masonry mortar was accomplished by the partial replacement of Portland cement, quicklime or hydraulic lime with large volumes (up to 70%) of cereal ash waste. The properties investigated under this study include material characterisation and compressive strength and durability using freeze–thaw tests. The results obtained suggest that there is potential for the manufacture of sustainable construction materials such as bricks and mortar from cereal ash, bottom ash and magnesium oxide ash waste streams.

Durability against Wetting–Drying Cycles of Water Treatment Sludge–Fly Ash Geopolymer and Water Treatment Sludge–Cement and Silty Clay–Cement Systems

AbstractThe viability of using two waste materials, water treatment sludge (WTS) and fly ash (FA), for developing sustainable masonry units has been previously investigated in terms of strength but the important aspect of durability against wetting–drying (w–d) cycles has yet to be studied. A study on durability against w–d cycles, an important parameter for service life design of the sustainable masonry units, is investigated in this paper. The liquid alkaline activator (L) was a mixture of sodium silicate (Na2SiO3) and sodium hydroxide (NaOH), and a high calcium fly ash (FA) was used as a precursor. The results of cyclic w–d test indicate that the WTS–FA geopolymer manufactured with an optimum ingredient (L:FA=1.6, Na2SiO3:NaOH=90∶10) and at an optimum heat condition of 85°C for 72 h can be used as durable bearing masonry units; i.e., the compressive strength is greater than 12 MPa after 12 w–d cycles. For this optimum ingredient, the w–d cycle strength, qu(w−d) at heat temperatures between 65 and 95°C ...

Alternatives to Conventional Cement-Sand Mortar for Sustainable Masonry Construction

Masonry Mortar is basically a binding agent that is composed of cementitious material, fine aggregates and water. The main purpose of the mortar is to sew masonry units (blocks/bricks) into single integral unit. Conventionally used mortar is cement sand mortar in the proportion 1:6 (Cement: River Sand). Over the past few decades man has exploited the natural resources at a severe rate. Good quality Natural River Sand stands first in the list of construction materials that are in the verge of extinction due to excessive and unnecessary consumption in construction process. One has to adapt to alternative materials that can be used as an effective replacement over ‘Natural River Sand’ in Masonry Mortar without affecting its efficiency. This paper focuses on the experimental analysis on six such alternatives that have the potential to replace Natural River Sand in mortar. Mortars prepared from these alternatives satisfies the minimum strength requirement as per IS code. Thus the use of such alternatives to natural sand for mortars in masonry construction would deliver an efficient-economical and sustainable structure.

The use of optimisation for enhancing the development of a novel sustainable masonry unit

This paper examines whether it is possible to utilise optimisation techniques to enhance the efficiency of the experiment-based development of a new product. Conventionally, a laboratory-based experimental investigation requires to check all combinations of all independent parameters describing the product; hence the optimum levels of the tested parameters is obtained. As a result there may be many thousands of samples produced to optimise these parameters; this is a time consuming, costly and laborious process. Instead, it is suggested that an empirical model is established and validated using the results of the laboratory investigation making it suitable for optimisation.In this paper the empirical model describes the compressive strength of a new masonry unit (bitublock) in terms of two parameters that are the proportion of the coarse aggregate and the compaction pressure. The expression for the compressive strength obtained from all experimental data was optimised showing a similar result to that from an experimental investigation. A much reduced set of experimental data was then used to establish further empirical models. The predictions from these models were compared with the output from the full set of experimental data to assess the accuracy of these empirical models and arrive at recommendations for the reduction of an experimental programme for future studies.From the experimental investigation alone, the optimal compressive strength (35.82MPa) of the new unit was obtained from a mix containing 30% coarse aggregate compacted at 24MPa. Empirical modelling using only half of the original experimental data predicted that a coarse aggregate content of 31.95% and a compaction pressure of 21.73MPa would provide an optimum compressive strength of 35.95MPa. This shows that the use of optimisation techniques can improve the efficiency and economy of laboratory investigations and also has a potential to provide economies during future scaling-up and manufacturing processes, e.g. in this case, by reducing compaction pressures.

Sustainable Masonry Constructions: Initial structural tests of brick and hemp‐lime composite walls

AbstractThe work presented in this paper is part of a larger project investigating methods of reducing environmental impact, and improving performance, of fired clay brick masonry walls. Brick masonry has been combined with natural, sustainable materials in order to create a construction system that is structurally and thermally efficient. This is being accomplished through a programme of desk based research and physical testing on both small and full scale samples. The sustainable materials chosen for use in the project are unfired clay bricks and hemp‐lime.The paper presents initial results from an on‐going experimental programme investigating performance of novel hemp‐lime and brickwork composite walls. Hemp‐lime provides sufficient thermal resistance to act as the insulative material in a wall construction. Due to its low structural strength and stiffness it has not been used in structural applications to date. Results from preliminary testing suggest that combining structural brickwork with a hemp lime inner leaf can result in some structural benefits despite its low strength. This hypothesis has been investigated further at a larger scale. Results of these initial tests are presented.Nachhaltige Mauerwerkskonstruktionen: Erste Versuche an Verbundwänden aus Ziegeln und Hanf‐Kalk. Die in diesem Beitrag vorgestellte Arbeit ist Teil eines größeren Projektes zu Untersuchungen zur Verminderung von Umweltauswirkungen, sowie zur Verbesserung des Verhaltens von Wänden aus Ziegelsteinen. Ziegelmauerwerk wurde mit natürlichen, nachhaltigen Materialien kombiniert, um ein Bausystem zu schaffen, welches von der Tragwirkung und der Energieeffizienz her leistungsfähig ist. Durch Simulationen und Versuche sowohl an verkleinerten als auch an 1 : 1‐Modellen wurde dies erreicht. Die nachhaltigen Materialien, die für das Projekt ausgewählt wurden, sind ungebrannte Lehmziegel mit Hanf‐Kalk.Der vorliegende Beitrag präsentiert erste Ergebnisse aus einer laufenden Untersuchung zum Verhalten von neuartigen Mauerwerkswänden, die aus Hanf‐Kalk und Ziegelmauerwerk kombiniert werden. Hanf‐Kalk bietet eine ausreichende thermische Beständigkeit, um als Dämmmaterial in einer Wandkonstruktion zu fungieren. Aufgrund seiner geringen Festigkeit und Steifigkeit kam es bisher nicht zu einer Anwendung bei baulichen Konstruktionen. Die Ergebnisse aus Vorversuchen lassen vermuten, dass die Kombination des tragenden Ziegelmauerwerks mit Hanf‐Kalk als innerer Schale trotz ihrer geringen Festigkeit zu einigen Vorteilen führen kann. Diese Hypothese wurde in größerem Maße weiter untersucht. Die Ergebnisse dieser ersten Tests werden vorgestellt.

Sustainable masonry mortar for brick joint and plaster in the UK

Blended mixtures of ground granulated blastfurnace slag and Portland cement were used in making sustainable masonry mortars suitable for brick joints and for plastering, with Portland cement mortar as control. The testing programme included the determination of a relationship between the mortar flow value and mortar water demand for a wide range of mix compositions. The mortar tensile strength is not a very critical property due to the fact that brickwork mortar is not usually under tension when in service; however, this parameter was determined in the laboratory using a standard briquet towing/testing machine. Chemical durability of the control and blended mortar in aggressive sulfate-bearing exposure conditions was investigated. The relationship between compressive strength of the mortar cured in water and in sodium sulfate solution at room temperature (20 ± 2°C) for from 3 to 120 days was established. The results demonstrated that after a prolonged period of exposure, significant strength and weight loss in the control mortar was observed. This phenomenon is explained, due to calcium hydroxide production as a consequence of Portland cement hydration, change in mortar morphology, inhibition of reaction species and the final disruption of the mortar matrix, resulting in loss of strength and weight at late age. The results obtained suggest that ground granulated blastfurnace slag can be incorporated into Portland cement for the development of sustainable and durable mortars in the UK.

Mechanical properties of natural fibers reinforced sustainable masonry

This research evaluates the physical and mechanical properties of Portland cement masonry blocks reinforced with lechuguilla natural fibers, that were lightened with 2-l bottles of polyethylene terephthalate. A concrete mix was designed for a target compressive strength of 16 MPa at 28 days, and slump of 70 mm. Masonry concrete blocks with dimensions of 730 × 340 × 130 mm were produced for two different fiber lengths (25 and 50 mm) and with fiber contents of 0.25%, 0.50%, 0.75% and 1.0%. Based on the obtained results, it was found that as the aspect ratio decreases the compressive strength increases and that the use of natural fiber (Vf = 0.5–0.75%) improves masonry post-cracking features, showing a ductile behavior and generating a uniform cracking pattern in the longitudinal sides of the blocks.

More Sustainable Masonry Façades: Preheating Ventilation Air Using a Dynamic Buffer Zone

During sunny conditions, surface temperatures on masonry façades can rise to over 40°C above the ambient temperatures. Conventional wall designs minimize the benefits of this solar heat through the use of thermal insulation. However, air that is drawn from the outdoors, between the façade and sheathing, can be used to recover heat from the masonry. The system, which utilizes a dynamic buffer zone (DBZ), acts as a solar air collector. This system can provide an effective way to preheat ventilation air at little to no extra cost, while not compromising the architectural features of the masonry wall system. A numerical model was developed to predict the amount of heat recovery possible using a DBZ. The numerical model was verified by comparing results with a commercial computational fluid dynamics software package and by conducting laboratory experiments. Preliminary results indicate that the DBZ as a solar air collector can achieve as high as 33% daily solar efficiency and seasonal solar efficiencies of up to 27%. Since this system is low-cost, yet effective, it may offer designers an opportunity to build more sustainable masonry wall systems.

A new masonry arch bridge assessment strategy (SMART)

About 40% of the European railway bridge stock comprises masonry arch bridges and over 60% of these are over 100 years old. All are ageing and most are carrying loads well in excess of those envisaged by their builders. The maintenance and assessment of these bridges is a constant concern for the bridge owners. Although current masonry arch bridge assessment methods are able to predict the ultimate carrying capacity of the bridge with some confidence, serious concerns have been identified with respect to predicting long-term behaviour and residual life. A new assessment procedure (sustainable masonry arch resistance technique (SMART)) is presented which differs philosophically from all the current techniques in as much as it takes a holistic approach in considering all possible modes of failure that the structure may experience under any given loading regime. Limit states are discussed and a new permissible limit state that is specific for masonry is proposed. The method advocates consideration of the permissible working loads, long-term behaviour and residual life of the bridge. This enables the assessing engineer to prioritise conflicting maintenance demands on limited budgets. The method is based upon recent research related to the long-term fatigue performance of masonry arch bridges subjected to cyclic loading.