Geopolymer materials can be formulated with a variety of precursors rich in aluminosilicates. However, some of these precursors, which are industrial by-products, are not widely available in the world. Therefore, there is a need to explore alternative potential precursors derived from natural sources. This study investigates the viability of using natural zeolite utilization as a part of the precursor in one-part ground granulated blast furnace slag (GGBFS)-based geopolymer mortars activated with sodium metasilicate. Geopolymer mortars were made with 0–90 wt% natural zeolite and cured at ambient and 40 ℃ temperatures. Fresh and hardened properties were evaluated. The test results showed that zeolite addition reduced the workability and setting time of the fresh mortar, significantly. Furthermore, the mechanical strength dropped with increasing zeolite content due to the microporous structure of the zeolite particles and weak reaction products. The microstructural examination showed that the mortars containing zeolite had a more porous structure compared to the pure slag mortar. Furthermore, heat-curing increased the mechanical strength in all mortars and densified the microstructure.

Highlights • Nano lime densifies the matrix, which improves the mechanical properties of nLC3 composite. • The micromechanical model of ECC was used to find critical volume fraction of fibers. • The use of nLC3 based ECC can help to lower the carbon footprints by 50%. • The mechanical properties of nLC3 ECC were significantly improved as compared to LC3 ECC. The construction industry is responsible for around 5% of total CO2 emissions globally. As a result, recent research is focused on the sustainability aspects of construction materials. Engineered cementitious Composites (ECC) are high-performance fiber reinforced composites with improved ductility and tensile strength but utilize higher cement content, raising concerns about their sustainability. In this study, nano-lime and calcined clay are combined with cement to develop a high strength sustainable nano lime calcined clay cement (nLC3) based Engineered Cementitious Composite (ECC). Initially, the packing density model was employed to develop a high strength nLC3-based matrix by combining the particle packing models and chemical compatibility while keeping costs to a minimum. Micromechanical modeling was then applied to determine the critical volume of fibers for the novel matrix using single fiber pullout tests and matrix toughness tests. According to the micromechanical model, the critical volume fraction is found to be 1.93% for the nLC3 mix. This was further confirmed by casting dog bone samples containing 2% fibers by volume which confirmed strain hardening response. The uniaxial test results indicated a strength of around 5.85 MPa in tension and 51 MPa in compression with about 3% tensile strain. These results are comparable to conventional ECC and better than previously developed LC3 based ECC. This study reveals that nLC3-based ECC is a more sustainable composite as compared to conventional ECC mix without any compromise on strength and cost.

Highlights • The high-temperature stability of CMEAM under static and dynamic load was compared. • Fatigue performance of CMEAM considering water damage was investigated. • Constitutive model was built for CMEAM. Cold mixed epoxy asphalt mixture (CMEAM) is widely applied on steel deck bridge pavements due to its excellent high temperature and fatigue resistance. However, previous studies investigated above two properties through destructive test or without considering water-damage factor, respectively, which is far away from real servicing condition. To distinguish above two properties of EA-05 and EA-10 (mixture with nominal maximum particle size of 4.75 mm and 9.5 mm), uniaxial static creep tests, dynamic modulus test and four-point bending beam fatigue test were applied in this paper. At the same time, to comprehensively acquire elastic, viscous-elastic and plastic performance of CMEAM, four kinds of constitutive models were also put forward. Results showed that seven-element viscous-elastic-plastic creep model has the highest correlation coefficients which proves there exists plastic deformation in CMEAM. Meanwhile, EA-10 is likely to present viscous-elastic deformation while EA-05 is more likely to show plastic deformation. Dynamic modulus among different gradation type mixture at 40 °C is not so apparent. But with the increase of frequency and testing temperature, this difference would be clear. The middle gradation of EA-10 has the most excellent high temperature stability under dynamic load. In terms of the resistance to fatigue damage of control or freeze-thaw treated samples, EA-05-U(the upper limit of EA-05 gradation type) always takes the first place and has the lowest sensitivity to the change of stress level and water damage.

In this study, three-stage research was carried out to investigate the adverse effects of openings in flat slabs. In the first stage of the study, full-scaled reinforced concrete two-way slabs were produced and exposed to a punching load. One of the test specimens was the reference test element produced without openings. For the other test specimens, the number of openings, the location of the opening, and the size of the opening were chosen as variables. The punching strength, initial stiffness, and energy dissipation capacity of the slabs were calculated with the load-displacement data recorded during the experiment. In the second stage of the study, the punching capacities of the test specimens were calculated by means of the punching capacity estimation equations presented in international regulations and compared with the experimental data. In the last stage of the study, the superposition principle, which is among the general principles of mechanics and has not been used before in the literature, was utilized. Considering the opening conditions presented in this study and the literature, it was investigated whether the new opening condition that will arise can be predicted with experimental data via the superposition principle.

In this paper, the subgrade waterproof membrane was proposed to achieve single-direction water-blocking by inhibiting the capillary rise and the downward infiltration of subgrade water. Further, the vertical migration mechanism of water in the waterproof membrane was revealed from the fluid potential perspective. It is found that when the consumption of Organic Silane per unit Area (OSA) is 0–4 g/m2, the water can migrate vertically and the waterproof membrane cannot inhibit the capillary rising, whereas the subgrade rainfall can infiltrate downward. At 6 g/m2, the capillary rise height of 20 cm can be inhibited, and the subgrade rainfall can infiltrate downward. At 8 g/m2, the capillary cannot rise, and the subgrade rainfall can infiltrate. At 10 g/m2 and 15 g/m2, the capillary cannot rise, subgrade rainfall is difficult to infiltrate downward, and water is difficult to migrate vertically in the waterproof membrane. Choosing 10 g/m2 consumption of OSA in the subgrades is recommended.

The use of High Strength Concrete Filled Steel Tube (HSCFST) members has become widespread, but there is limited research on their creep behavior. This study examines the creep and shrinkage characteristics of HSCFST columns subjected to axial loading by testing fifteen specimens with various steel ratios over a period of 365 days. The experimental data is then compared to the predictions made by the creep prediction models MC 90, ACI 209, and AFREM. The results indicate that the creep coefficients of HSCFST specimens are significantly lower than those of plain concrete specimens. By the end of 365 days, the creep coefficient of plain concrete is more than twice that of concrete in HSCFST. The steel ratio has a slight effect on the creep of CFST specimens, with the creep coefficient decreasing as the steel ratio increases. The comparison of the results shows that the MC 90 and ACI 209 models overestimate the creep of concrete, while the AFREM model underestimates it. Furthermore, the ACI 209 model is modified based on the experimental results by applying a correction factor of concrete strength, which significantly improves its accuracy and makes it suitable for predicting the creep of high strength plain concrete and HSCFST.

Highlights ● Marine soil with CG-CCR geopolymer showed excellent engineering performance. ● Geopolymer content, initial water content, and curing age control the enhancement. ● Durability is affected by the geopolymer content and initial water content. ● Mass loss is a prominent factor in strength reduction after wetting-drying cycles. ● Microstructure of marine soil was improved by reaction products of geopolymer. Constructing infrastructure on soft soils demands the implementation of ground improvement. This study proposed an eco-friendly method of stabilizing marine soil using a calcium carbide residue (CCR)-activated coal gangue (CG) geopolymer derived from industrial waste. Laboratory experiments were conducted to investigate the mechanical properties, durability performance, and stabilization mechanisms of stabilized marine soils under multiple wetting-dry cycles. The results highlighted the effectiveness of CG-CCR geopolymer by a content of 15% to achieve satisfactory strength gain over the engineering requirements. However, the largest decrease in strength (71.89%) was observed when the initial water content was beyond 1.5 times the liquid limit (LL). The optimum solution was proposed to have a geopolymer content of 15% or an initial water content of 1.25·LL to exhibit the highest resistance to strength decay after 12 cycles. Compared with water intrusion, mass loss had a more significant effect on soil strength deterioration. The formation of noncrystalline or amorphous-phase reaction products effectively filled intergranular pores and reduced the void space between soil particles, improving the mechanical properties. The CG-CCR geopolymer was demonstrated to offer a promising solution for soil improvement in geotechnical engineering and waste reduction in industry as a soil stabilizer.

• A novel lab-scale ore granulator with adjustable inclined angle (0–30°) and rolling speed (30–150 rpm) is firstly developed. • Influence of physical, chemical, biological issues of copper sulfides agglomeration is revealed; • Powder bonding, leaching and structural feature of well-shaped agglomeration (WAs) is evaluated. • Multi-factor 3D response features of WAs preparation is carefully discussed. The ore agglomerations could ameliorate intra-particle pore network, homogenize flow paths, and improve leaching efficiency of heap leaching. This paper innovatively develops a novel ore granulator with adjustable inclined angle and rolling speed. To comprehensively evaluate granulation procedure, the effects of physical (crushed feeds particle size distribution, rolling speed, inclined angle), chemical (binder type, curing time) and biological factors (bacterial concentration) on bonding performance of crushed feeds are analyzed. The objective of this paper is to obtain the optimal granulation conditions by studying the influence of various factors on the bonding ability, strength, and stability of granulated ores, in order to improve the pore structure of the heap leaching system, and increase the leaching rate of the ore. The results show that well-shaped agglomeration (WAs) does improve minerals leaching efficiency, and the uniaxial compressive strength of WAs is positively related to curing time, binder concentration, inclined angle, and rolling speed. The excessive lower or higher rolling speed is not suitable to get a higher extraction rate due to undesirable disintegration or compaction. The higher concentration (0.5–10 %) sulfuric acid solution could obviously increase WAs strength from 32.6 KPa to 48.3 KPa. The organic binders such as polyacrylamide are benefit for powders bonding and increase the compressive strength, but does not good for the desirable leaching reaction rate. The bacterial pre-adding has no significant positive influence on bonding and leaching efficiency. Relied on the 3D response surface, the preferred preparing condition is: 78.9 rpm rolling speed, 30° inclined angle, 7-days curing time and 9.3 % H2SO4 solution. Future studies should focus on exploring the intrinsic correlation between the various factors and evaluating the granulating and leaching effects from the perspective of chemical detection and leaching bacteria. Graphical Download : Download high-res image (254KB) Download : Download full-size image

Surface water is commonly acknowledged as the most polluted among the several water sources available. The principal pollutants consist of various industrial toxins, organic dyes, and heavy metals, specifically found in surface runoffs. The potential for enhancing water quality through the extraction of pollutants from runoff appears promising with the implementation of porous concrete, in conjunction with other additives. This study investigates the impact of varying quantities of coarse and fine aggregates, with variable water-to-cement ratios, on the mechanical properties of concrete. Furthermore, the effectiveness of MWCNT in the removal of chemical oxygen demand (COD) and the dye pollutant methylene blue via surface absorption and production cost are examined in this research. The results reveal that the MWCNT had significant effectiveness in removing COD and dye pollutants from surface runoff water. The greatest rate of COD removal observed was 71.34 %, while the maximum percentage of dye removal was 91.89 %. In addition, the integration of MWCNTs into the porous concrete matrix yielded improved mechanical characteristics, indicating a positive influence of this addition. Concerning the cost of samples, the inclusion of MWCNT resulted in an increase in the overall cost. However, the utilization of porous concrete pavements offers a promising prospect for cost savings, and with advancements in water purification and mechanical qualities, this method has considerable benefits.

Addressing the scarcity of research on the residual expansion deformation of steam-cured concrete and its underlying factors, this study introduces a testing apparatus to characterize the internal stress in fresh concrete during the thermal treatment. It explores the impact of water-to-cement ratio (w/c) and paste-to-aggregate ratio (p/a) on internal stress and elucidates the developmental patterns of internal stress in concrete throughout the thermal treatment phase. The key findings are as follows: (i) During the thermal treatment, the internal stress in concrete under constraint is predominantly compressive, exhibiting a rapid increase in the heating stage, followed by a gradual decline in the constant temperature treatment stage, and a continued decrease with a decelerating trend during the cooling stage. (ii) Both w/c and p/c significantly influence internal stress in concrete, and this stress can be enhanced by reducing the initial free water content and augmenting the initial structural strength of the concrete. This paper serves as a valuable foundation and reference for further investigations into the residual expansion deformation of steam-cured concrete.