Fly Ash an Alternative of Clay in Bricks: A Sustainable Solution for Future Constructions

Clay (CL) bricks have been commonly used in construction industry for centuries. The negative environmental impacts of use of CL bricks include rapidly depleting fertile clayey layer of soil and the high energy consumption of CL bricks, which have led to the development of alternative brick units incorporating waste materials. Fly ash (FA) brick has been identified as a sustainable and environmental friendly alternative of traditional CL brick, which reduces carbon dioxide (CO2) emissions and hence global warming. This study aims to develop eco-friendly geopolymer mortar brick mixes using FA and CL without heat curing and applying molding pressure. This study investigates influences of percentage replacements of CL with FA and curing period on the compressive strength (CS) of geopolymer mortar brick mixes. In the preparation of geopolymer mortar mixes, the percentage replacements of CL with FA varied from 0 to 100% (0%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% and 100%) using 12 M sodium hydroxide (NaOH) solution. A total of 11 geopolymer mortar mixes were cast and cured at 14, 28, 56 and 90 days. The optimum CS of 49.7 MPa with 80% replacement of CL with FA using 12 M NaOH solution at 90 days was achieved. This study is expected to contribute in reducing the level of CO2 emissions, which will subsequently reduce global warming and smog formation in Pakista

Behavior of Scaled Infilled Masonry, Confined Masonry & Reinforced Concrete Structures under Dynamic Excitations

This research investigates the nonlinear behavior of scaled infilled masonry (IFM), confined masonry (CM), and reinforced concrete (RC) structures by utilizing and validating two tests from the literature as benchmarks. The validation was based on a comparison with the pushover results of small-scaled physical tests and their numerical modeling. Numerical modeling of small-scale (1:4 and 1:3) IFM, CM, and RC models has been carried out with Finite Element Modelling (FEM) and Applied Element Modelling (AEM) techniques using SAP2000 and the Extreme Loading for Structures (ELS) software, respectively. The behavior of the structure under lateral loads and excitations was investigated using nonlinear static (pushover) and nonlinear time history (dynamic) analysis. The evaluation of the pushover analysis results revealed that for IFM, the %age difference of tangent stiffness was 4.2% and 13.5% for FEMA Strut and AEM, respectively, and the %age difference for strength was 31.2% and 2.8% for FEMA Strut and AEM, respectively. Similarly, it was also calculated for other wall types. Dynamic analysis results from FEM and AEM techniques were found in the fairly acceptable range before yield; however, beyond yield, AEM proved more stable. Finally, the results also showed that the numerical study can be utilized for the evaluation of small-scale models before performing the physical test

A comparison of in-air and in-water calibration of a dosimetry system used for radiation dose assessment in cancer therapy

An accurate calibration of the therapy level radiation dosimetry system has a pivotal role in the accuracy of dose delivery to cancer patients. The two methods used for obtaining a tissue equivalent calibration of the system: air kerma calibration and its conversion to a tissue equivalent value (absorbed dose to water) and direct calibration of the system in a water phantom, have been compared for identical irradiation geometry. It was found that the deviation between the two methods remained within a range of 0% to ±1.7% for the PTW UNIDOS dosimetry system. This means that although the recommended method is in-water calibration, under exceptional circumstances, in-air calibration may be used as well

Experimental study on strength and endurance performance of burnt clay bricks incorporating marble waste

Burnt clay brick is one of the oldest and most widely used construction materials. The production of burnt clay bricks with various waste materials can help reduce the environmental hazards and improve brick performance at low manufacturing costs, thereby leading towards more sustainable construction. This research aimed to evaluate the effect of using waste marble powder (WMP) in varying percentages, i.e., 0, 3, 6, 9, 12, and 15%, by weight of clay in an industrial brick kiln plant. A range of mechanical and durability tests was performed on the raw material, i.e., clay, WMP, and bricks, to quantify their performance. It was observed that incorporation of WMP resulted in a reduced unit weight of the bricks, making the structure lighter in weight. Moreover, compressive strength and freeze thaw test results for all the brick specimens and sulfate tests for the brick specimens with 12% WMP addition were within the Building Code of Pakistan, and ASTM C67 prescribed limits. Finally, it can be concluded that WMP up to 12% by weight of clay can be incorporated to prepare burnt clay bricks, which can reduce the environmental waste to achieve sustainability and economy for the brick industry

Impact of Openings on the In-Plane Strength of Confined and Unconfined Masonry Walls: A Sustainable Numerical Study

While openings are an essential requirement in buildings as a source of access, fresh air and sunlight, these openings cause a reduction in the lateral stiffness and torsional resistance of masonry wall units. A detailed numerical investigation was carried out to explore the impact of the opening percentage on the in-plane stiffness and lateral strength of unconfined and confined masonry wall panels prepared using calcium silicate bricks, for sustainable masonry structures. A commercially available FEM package (ANSYS) was used to carry out comparative analysis of ten wall panels, five of each type (confined and unconfined masonry walls) with concentrically located openings of varying sizes (0% to 16.5%). A simplified micro-modeling technique following the Newton Raphson Algorithm was adopted. Results revealed that the confined masonry approach unveiled a more reliable anti-seismic response along with improved in-plane strength in the case of confined masonry walls. The failure type shifted from pure flexural to more of a blend of shear and flexure after the opening percentage increased to 10.09% in unconfined masonry walls, which was not the case where confinement was provided. Based on the outcomes, it is strongly recommended to adopt confined masonry in highly seismic-prone areas to avoid catastrophic damage caused by earthquakes

Feasibility of Using Coal Ash for the Production of Sustainable Bricks

In this research study, environmentally friendly unburnt coal ash (CA) bricks were investigated as an alternative to conventional burnt clay bricks. In this research study, various physical and mechanical properties of unburnt CA bricks were investigated. The unburnt CA bricks were prepared by using 60% CA and 10% lime by weight. In these unburnt CA bricks, varying cement contents (5%, 10%, and 15%), sand contents (10% and 15%), and quarry dust contents (5% and 10%) by weight were used. A forming pressure of 29 MPa was applied through an automatic pressure control system either for 3 s or 6 s. The prepared bricks were moist cured for 28 days. The experimental results exhibited that unburnt CA bricks with 10% cement, 10% sand, and 10% quarry dust subjected to forming pressure for 3 s exhibited the highest compressive strength of 19 MPa and flexural strength of 2.1 MPa. The unburnt CA bricks exhibited reduced water absorption, reduced efflorescence, and lower weight per unit area than the conventional clay bricks. A cost comparison of unburnt CA bricks and clay bricks exhibited that unburnt CA bricks are cost-effective compared to clay bricks

Impact of Openings on the In-Plane Strength of Confined and Unconfined Masonry Walls: A Sustainable Numerical Study

While openings are an essential requirement in buildings as a source of access, fresh air and sunlight, these openings cause a reduction in the lateral stiffness and torsional resistance of masonry wall units. A detailed numerical investigation was carried out to explore the impact of the opening percentage on the in-plane stiffness and lateral strength of unconfined and confined masonry wall panels prepared using calcium silicate bricks, for sustainable masonry structures. A commercially available FEM package (ANSYS) was used to carry out comparative analysis of ten wall panels, five of each type (confined and unconfined masonry walls) with concentrically located openings of varying sizes (0% to 16.5%). A simplified micro-modeling technique following the Newton Raphson Algorithm was adopted. Results revealed that the confined masonry approach unveiled a more reliable anti-seismic response along with improved in-plane strength in the case of confined masonry walls. The failure type shifted from pure flexural to more of a blend of shear and flexure after the opening percentage increased to 10.09% in unconfined masonry walls, which was not the case where confinement was provided. Based on the outcomes, it is strongly recommended to adopt confined masonry in highly seismic-prone areas to avoid catastrophic damage caused by earthquakes

Utilization of Fly Ash as a Viscosity-Modifying Agent to Produce Cost-Effective, Self-Compacting Concrete: A Sustainable Solution

Sufficient deformability can be achieved in concrete while maintaining segregation resistance either by using a chemical viscosity-modifying admixture (VMA) or increasing the fine content in the concrete. Using VMA, the initial cost of self-compacting concrete (SCC) increases, making it unsuitable for general construction. As a result, alternative methods for lowering the cost of SCC must be investigated. In this study, we assess the effectiveness of fly ash (FA) as a viscosity-modifying agent in the production of cost-effective and durable SCC. We also forge new pathways for sustainable development. The percentage of FA, superplasticizer dose, and water/binder ratio were varied, whereas the amounts of cement and water, as well as fine/coarse aggregate content were kept constant. Fresh properties, such as flow, filling and passing abilities, viscosity, and segregation resistance, were measured. Compressive/flexural strength, density, water absorption, and rate of water absorption of hardened SCC were also determined. The test results showed that fly ash can be used as an alternative to a VMA to produce cost-effective, self-compacting concrete. The slump flow of the various fresh-state concrete mixes ranged from 200 to 770 mm, with an L-box ratio of 0 to 1 and a flow time of 2.18 to 88 s. At 28 and 56 days, the compressive strengths of the concrete mixes with fly ash were found to be comparable to those of the control concrete mixes with VMA. The cost of ingredients for a specific SCC mix is 26.8% lower than the price of control concrete, according to a cost comparison assessment

Concrete incorporating supplementary cementitious materials: Temporal evolution of compressive strength and environmental life cycle assessment

The use of Supplementary Cementitious Materials (SCMs) or industrial wastes as a partial replacement for cement in the production of concrete is an urgent need in the construction industry due to cement's growing environmental challenges and rising cost. In respect of this, we conducted research work on proportioning binary concrete mixes. Fly ash (FA) replaced 10 %, 20 %, and 30 % of the cement, while silica fume (SF) replaced 5 %, 10 %, and 15 % of the cement. A control concrete mix was also developed with 100 % cement and no SCM. The results showed no increase in compressive strength for FA concrete compared to control at the early age of 3–28 days, but a maximum increase in compressive strength of 4 % was discovered at a later age of 56 days for concrete with 20 % FA. For 5 % SF concrete, a considerable strength increase of 15 % was seen at the early age of 3 days. Like with FA concrete, 2 % improvement in strength was recorded at the later age of 56 days for 10 % SF concrete. This study further focused on the concrete's temporal evolution of compressive strength by developing a strength evolution model (SEM) using nonlinear regression analysis at a 95 % confidence level. Pearson correlation coefficient was used to determine the correlation between the model values and the experimental results. For comparison, the fib Model Code 2010 was applied to the experimental data, and a good agreement was observed among the proposed model, the fib Model values, and the experimental results. The proposed model can be expanded to address further regression-related problems. Finally, environmental life cycle assessment revealed that utilizing 10 %, 20 %, and 30 % of FA lowered Global Warming Potential (GWP) by 9 %, 19 %, and 29 %, respectively. Likewise, using 5 %, 10 %, and 15 % of SF reduced the GWP by 5 %, 9 %, and 14 %