Low-Carbon and Fundamental Properties of Eco-Efficient Mortar with Recycled Powders

Using recycled powders from solid waste is accepted as an effective strategy to realize the sustainable development of the construction industry. In our study, the cement was substituted by two kinds of recycled powders, i.e., spontaneous combustion gangue powder (SCGP) and recycled concrete powder (RCP), with a certain replacement ratio of 30%. The experimental variables were mainly the type of replacement powder (e.g., SCGP, RCP, and SCGP + RCP) and the grinding time of RCP (e.g., 25 min, 50 min, and 75 min). The fundamental properties, including mechanical properties, long-term properties, and carbon emission, were analyzed for all the mortar mixtures. Experimental results indicate that incorporation of RCP contributes to enhancing the toughness and dry shrinkage resistance of eco-efficient mortar, while SCGP positively affects the compressive strength and chloride resistance. The grinding process improves the activity of RCP to a certain extent, while a long grinding time leads to fusion and aggregation between powders. Investigation on CO₂ emission demonstrates that carbon emission from cement production accounts for the largest proportion, 80~95%, in the total emission from mortar production. Combined with the AHP model, eco-efficient mortar containing 15% RCP ground for 50 min and 15% SCGP displays optimal fundamental properties.     

Influence of Polymer Modifiers on Selected Properties and Microstructure of Cement Waterproofing Mortars

This paper presents the results of research on the influence of polymer modifiers: styrene-acrylic copolymer, vinyl acetate/ethylene (EVA), vinyl acetate/acrylic copolymer (VAAc), and VA/VeoVa/acrylic terpolymer on the water permeability and adhesion of cement-containing waterproofing mortars in concrete. The content of the polymers in the composition of the mortars was 15, 20 and 26% (m/m) in relation to the weight of the dry ingredients. Using microscopic methods, an attempt was made to analyse the relationship between the microstructure of the mortars and the properties of these polymers. The EVA and the vinyl acetate/acrylic copolymer, which were used in the form of dry powders, had the most favourable effect on water permeability and adhesion to the concrete substrate. They may prove to be useful for the production of one-component cement-containing waterproofing mortars. On the other hand, the VA/VeoVa/acrylic terpolymer modifier had the least favourable effect on the tested properties. For mortars with this modifier, the desired water-permeability parameters were not achieved. Depending on the amount of polymer modifier, the mortars were characterized by differences in watertightness, as established on the basis of changes in porosity and differences in the adhesion of the cement-polymer paste to the surface of aggregate grains. It was determined that the type of polymer and its dispergation properties influence the water permeability of mortars, as well as their adhesion to concrete substrates.     

Investigation into the Integration of Impregnated Glass and Carbon Textiles in a Laboratory Mortar Extruder (LabMorTex)

A promising process for the automatization of concrete structures is extrusion or extrusion molding. An innovative approach is the extrusion of concrete with imbedded technical textiles as reinforcement. For a successful extrusion, the rheological properties of the fresh concrete have to be optimized, as it must be extrudable and have sufficient early strength after leaving the mouthpiece. Within the scope of this paper, a process was developed which allows the integration of flexible as well as stiff impregnated textiles into the extrusion process. For this purpose, different textile-reinforced mortars (TRM) were extruded and their material characteristics were investigated. The results show that the mortar cross-section is considerably strengthened, especially when using carbon textiles, and that extrusion has considerable potential to produce high-performance TRM composites. In uniaxial tension tests with TRM, as well as in the pure roving tensile strength tests, textile stresses of approx. 1200 MPa were achieved for the glass textile and approx. 2250 MPa for the carbon textile. The position of the textile layer deviated a maximal 0.4 mm from its predesigned position, which shows its potential for producing tailor-made TRM elements. In addition, by adjusting the mortar mix design, it was possible to reduce the global warming potential (GWP) of the extrusion compound by up to 49.3% compared to the initial composition from preliminary studies.     

Compressive Fatigue Behaviour of High-Strength Concrete and Mortar: Experimental Investigations and Computational Modelling

A high-strength concrete and mortar subjected to compressive fatigue loading were comparatively investigated using experimental and computational techniques. The focus of the investigations was on the influence of the coarse aggregate in high-strength concrete. Accordingly, the fatigue behaviour was analysed experimentally using the macroscopic damage indicators strain, stiffness and acoustic emission hits. The results clearly show differences in the fatigue behaviour between the concrete and the mortar, especially at the lower stress level investigated. The basalt coarse aggregate here improves the fatigue behaviour of the concrete. Indication of a negative effect can be seen at the higher stress level. A finite element approach with a gradient-enhanced equivalent strain-based damage model combined with a fatigue model was used for the computational simulation of the fatigue behaviour. The damage model includes a differentiation between tension and compression. The fatigue model follows the assumption of the reduction in the material strength based on the accumulated gradient-enhanced equivalent strains. A random distribution of spherically shaped basalt aggregates following a given particle size distribution curve is used for the simulation of concrete. The comparison of the experimentally and computationally determined strain developments of the concrete and mortar shows very good agreement.     

通络醒神针法联合缪刺法治疗脑卒中后运动性失语症临床研究

[目的]探讨通络醒神针法联合缪刺法治疗脑卒中后运动性失语症临床疗效。[方法]将70例脑卒中后运动性失语症患者按照随机数字表法分为对照组和观察组,每组35例。两组均接受Schuell刺激疗法进行语言训练,对照组接受通络醒神针法,观察组在对照组治疗基础上采用缪刺法（取穴通里、神堂、神门）。比较两组治疗前后汉语言标准失语症检查量表评分、失语商、失语症严重程度分级、脑卒中失语症患者生活质量量表（SAQOL-39）评分、美国国立卫生研讨院卒中量表（NIHSS）评分及蒙特利尔认知评估评定（MoCA）评分。比较两组治疗总有效率。[结果]治疗后观察组语言功能各项评分、失语商、生活质量评分、Mo CA评分均高于对照组（P<0.05）,NIHSS评分低于对照组（P<0.05）。治疗后观察组与对照组在失语程度分级方面比较,差异有统计学意义（P<0.05）。观察组临床疗效总有效率为91.43%,高于对照组的74.43%(P<0.05)。[结论]通络醒神针法联合缪刺法可以改善脑卒中后运动性失语症患者的语言表达、理解及沟通能力,改善其神经功能缺损、认知功能及日常生活能力。     

Influence of Silica Modulus and Curing Temperature on the Strength of Alkali-Activated Volcanic Ash and Limestone Powder Mortar

This present study evaluates the effect of silica modulus (M_s) and curing temperature on strengths and the microstructures of binary blended alkali-activated volcanic ash and limestone powder mortar. Mortar samples were prepared using mass ratio of combined Na₂SiO_3(aq)/10 M NaOH_(aq) of 0.5 to 1.5 at an interval of 0.25, corresponding to M_s of 0.52, 0.72, 0.89, 1.05 and 1.18, respectively, and sole 10 M NaOH_(aq). Samples were then subjected to ambient room temperature, and the oven-cured temperature was maintained from 45 to 90 °C at an interval of 15 °C for 24 h. The maximum achievable 28-day strength was 27 MPa at M_s value of 0.89 cured at 75 °C. Samples synthesised with the sole 10 M NaOH_(aq) activator resulted in a binder with a low 28-day compressive strength (15 MPa) compared to combined usage of Na₂SiO_3(aq)/10 M NaOH_(aq) activators. Results further revealed that curing at low temperatures (25 °C to 45 °C) does not favour strength development, whereas higher curing temperature positively enhanced strength development. More than 70% of the 28-day compressive strength could be achieved within 12 h of curing with the usage of combined Na₂SiO_3(aq)/10 M NaOH_(aq). XRD, FTIR and SEM + EDX characterisations revealed that activation with combined Na₂SiO_3(aq)/10 M NaOH_(aq) leads to the formation of anorthite (CaAl₂Si₂O₈), gehlenite (CaO.Al₂O₃.SiO₂) and albite (NaAlSi₃O₈) that improve the amorphosity, homogeneity and microstructural density of the binder compared to that of samples synthesised with sole 10 M NaOH_(aq).     

Tensile Behaviour of FRCM Composites for Strengthening of Masonry Structures—An Experimental Investigation

This paper presents the results of direct tensile tests performed on six different FRCM (fabric reinforced cementitious matrix) strengthening systems used for masonry structures. The emphasis was placed on the determination of the mechanical parameters of each tested system and a comparison of their tensile behaviour in terms of first crack stress, ultimate stress, ultimate strain, cracking pattern, failure mode and idealised tensile stress-strain curve. In addition to the basic mechanical tensile parameters, accidental load eccentricities, matrix tensile strengths, and matrix modules of elasticity were estimated. The results of the tests showed that the tensile behaviour of FRCM composites strongly depends on the parameters of the constituent materials (matrix and fabric). In the tests, tensile failure of reinforcement and fibre slippage within the matrix were observed. The presented research showed that the accidental eccentricities did not substantially affect the obtained results and that the more slender the specimen used, the more consistent the obtained results. The analysis based on a rule of mixtures showed that the direct tensile to flexural tensile strength ratio of the matrixes used in the test was 0.2 to 0.4. Finally, the tensile stress–strain relationship for the tested FRCMs was idealised by a bi- or tri-linear curve.     

Mechanical resilience and cementitious processes in Imperial Roman architectural mortar

The pyroclastic aggregate concrete of Trajan’s Markets (110 CE), now Museo Fori Imperiali in Rome, has absorbed energy from seismic ground shaking and long-term foundation settlement for nearly two millenia while remaining largely intact at the structural scale. The scientific basis of this exceptional service record is explored through computed tomography of fracture surfaces and synchroton X-ray microdiffraction analyses of a reproduction of the standardized hydrated lime–volcanic ash mortar that binds decimeter-sized tuff and brick aggregate in the conglomeratic concrete. The mortar reproduction gains fracture toughness over 180 d through progressive coalescence of calcium–aluminum-silicate–hydrate (C-A-S-H) cementing binder with Ca/(Si+Al) ≈ 0.8–0.9 and crystallization of strätlingite and siliceous hydrogarnet (katoite) at ≥90 d, after pozzolanic consumption of hydrated lime was complete. Platey strätlingite crystals toughen interfacial zones along scoria perimeters and impede macroscale propagation of crack segments. In the 1,900-y-old mortar, C-A-S-H has low Ca/(Si+Al) ≈ 0.45–0.75. Dense clusters of 2- to 30-µm strätlingite plates further reinforce interfacial zones, the weakest link of modern cement-based concrete, and the cementitious matrix. These crystals formed during long-term autogeneous reaction of dissolved calcite from lime and the alkali-rich scoriae groundmass, clay mineral (halloysite), and zeolite (phillipsite and chabazite) surface textures from the Pozzolane Rosse pyroclastic flow, erupted from the nearby Alban Hills volcano. The clast-supported conglomeratic fabric of the concrete presents further resistance to fracture propagation at the structural scale.The builders of the monuments of Imperial Rome (from 27 BCE, when Octavian became Emperor Augustus, through the fourth century CE) used pyroclastic volcanic rock to create unreinforced concrete structures with dramatic vaulted spans, as at the Markets of Trajan (110 CE) (1, 2) (Fig. 1A). The concrete foundations, walls, and vaulted ceilings are composed of decimeter-sized volcanic tuff and brick coarse aggregate (caementa) bound by volcanic ash–lime mortar (Fig. 1B). The conglomeratic fabric of the concretes is analogous to sedimentary rocks made of coarse rock fragments and a matrix of finer grained material. The concretes have resisted structural scale failure during moderate-magnitude earthquakes (<8 on the Mercalli–Cancani–Sieberg intensity scale) associated with slip on Appennine fault systems 80–130 km to the northeast, as well as chemical decay associated with repeated inundations of foundations and walls by Tiber River floods (3–5). To date, at least six episodes of moment magnitude 6.7–7 ground shaking and damage to monuments have been recorded since 508 CE (4). The concrete structures contain common macroscale fractures, with rough surfaces that link by complex segment overlap and bridging, and either follow or traverse caementa interfacial zones (Fig. 1C). Many monuments remain in active use as residences, offices, museums, and churches. In addition to the Markets of Trajan, these include the Theater of Marcellus (44–13 BCE), Mausoleum of Hadrian (123–39 CE), Pantheon (ca. 126 CE), and Baths of Diocletian (298–306 CE). The monuments that did undergo sectional failure, for example at the Colosseum (70–90 CE), Baths of Caracalla (ca. 215 CE), and Basilica of Maxentius (ca. 313 CE), mainly did so in Late Antiguity or the Middle Ages, when they were several centuries old and had become vulnerable through subsurface instabilities; problematic structural design; removal of marble and travertine dimension stone, columns, and cladding; and lack of regular maintenance (4, 6, 7).Open in a separate windowFig. 1.Markets of Trajan concretes. (A) Great Hall, vaulted ceiling and brick-faced concrete walls; reprinted with permission from Archives, Museo Fori Imperiali. (B) Drill core with Pozzolane Rosse volcanic ash (harena fossicia) mortar and conglomeratic aggregate (caementa). (C) Fractures in vaulted ceiling, Grande Emiciclo: 1, crack follows caementa perimeter; 2, crack traverses caementa. Wall concrete contains ∼88 vol % pyroclastic rock: 45–55% tuff (and brick) as caementa, ∼38% volcanic ash pozzolan, and ∼12% lime paste, with 3:1 ash:lime volumetric ratio (de Architectura 2.5.1) in the mortar (18).The pozzolanic mortar perfected by Roman builders during first century BCE (8) is key to the durability of concrete components in structurally sound monuments well maintained over two millennia of use. [Pozzolans, named after pumiceous ash from Puteoli (now, Pozzuoli) in the Campi Flegrei volcanic district, react with lime in the presence of moisture to form binding cementitious hydrates (9)]. By the Augustan era (27 BCE–14 CE), after experimenting with ash mixtures for >100 y, Romans had a standardized mortar formulation using scoriaceous ash of the mid-Pleistocene Pozzolane Rosse pyroclastic flow (Fig. S1) that substantially improved the margin of safety associated with increasingly daring structural designs (10, 11). They used this mortar formulation in the principal Imperial monuments constructed in Rome through early fourth century CE (8). Pozzolane Rosse erupted at 456 ± 3 ka from nearby Alban Hills volcano (12), filling valleys and covering topographic plateaus across the Roman region; the ash has a highly potassic tephritic composition (13). Romans made the architectural mortars by calcining limestone at ∼900 °C to produce quicklime [CaO], hydrating the quicklime to form portlandite [Ca(OH)₂], a trigonal calcium hydroxide] putty, and laboriously incorporating granular Pozzolane Rosse ash. This is the red and black excavated sand (harena fossicia) described by the Roman architect Vitruvius in first century BCE (de Architectura 2.4.1–2.4.3; 2.5.1–2.5.3) (14). The strongly alkaline portlandite solution attacks the surfaces of the scoriaceous pozzolan; volcanic glass and silicate mineral textures dissociate; their alkali ions dissolve in the liquid phase; and calcium is adsorbed on the scoria surfaces, forming cementitious hydrates (9). These phases are regarded as central to the chemical durability that is an essential component of the impressive record of survival of many monuments, but their role in resisting mechanical degradation through obstructing microcrack propagation has never been examined.Fracture-mechanical properties offer important insight into a cementitious material’s long-term survivability (i.e., its ability to absorb energy from applied loads without failing catastrophically). Two common properties are uniaxial tensile strength [f_t (megapascals)], which refers to the stress at which a macrocrack initiates, and fracture energy [G_F (joules per square meter)], the amount of mechanical work required to propagate a macrocrack to create one square unit of new surface area (15). Experimental characterization of the fracture behavior of the Imperial-age mortar through tests of ancient material is difficult, because it occurs in narrow, irregular zones that are bonded to caementa (Fig. 1B), and the heterogeneous fabric of the concrete requires large test dimensions (16). We therefore duplicated the Imperial-age mortar using the volcanic ash–quicklime proportions described by Vitruvius (de Architectura 2.4–2.5) (14) and petrographic and mineralogical characterization of mortar samples from the Great Hall of Trajan’s Markets (17) to formulate a mix design that closely mimics the Trajanic formulation. Fracture-mechanical properties, as well as Young’s modulus, were previously determined at 28, 90, and 180 d hydration via an innovative arc-shaped three-point bending test (18) that reproduced half-slices of hollow 20-cm-diameter drill cores from the Great Hall (Fig. 1B), so that the behavior of the mortar reproduction can be compared with that of Trajanic concrete in a future experimental testing program. All measured properties increase with age, with the 180-d mortar producing values for Young’s modulus and uniaxial tensile strength around 1/10 of modern structural concrete, whereas fracture energy is close to one-half (Fig. S2) of the crack arrays in the reproduction at 28, 90, and 180 d hydration provide visualization of millimeter-scale fracture processes to which macroscale toughness associated with previously published G_F values are attributed (18). X-ray microdiffraction experiments with synchroton radiation are a critical analytic component, because they provide very fine-scale identifications of the cementitious mineral assemblage that evolved over 1,900 y. The Markets of Trajan concrete provides a proven prototype for innovations in monolithic concretes (19) that are reinforced by a clast-supported conglomeratic fabric at the macroscale and an enduring crystalline fabric at the microscale. New concrete materials formulated with pyroclastic aggregate based on the Imperial Roman prototype could reduce carbon emissions, produce crystalline cementitious reinforcements over long periods of time, enhance durability in seismically active regions, and extend the service life of environmentally sustainable buildings.

Table 1.

Mechanical properties of mortar reproductions

Influence of Redispersible Powder on Properties of Self-Leveling Mortar of Ternary Cementitious System

The self-leveling mortar (SLM) of a ternary cementitious system with different dosages of redispersible powder (RP) with ordinary Portland cement (OPC), sulfoaluminate cement (SAC), and calcium sulfate (CS) as cementitious materials was investigated with regard to fluidity, bond strength, shrinkage rate, abrasion resistance, flexural strength, and compressive strength. The performance parameters obtained from the experimental test for SLM were weighted values calculated with an analytic hierarchy process (AHP). The comprehensive index of performance was evaluated on the basis of a weighted-sum method, and the optimal dosage of RP was determined according to the comprehensive index. The experimental results demonstrated that the fluidity of SLM decreased with the increase in RP dosage at the beginning but then increased thereafter and decreased rapidly as the dosage went beyond 3.0%. The addition of RP resulted in a significant improvement in bond strength (of SLM), reduction in the shrinkage rate, abrasion loss, early flexural strength and compressive strength, and resistance to cracking. The properties of SLM with 3.0% RP can meet the requirements of the industrial standard for cementitious self-leveling floor mortar. Compared with the SLM without RP, the bond strength of SLM with 3.0% RP was increased by 46.7%, while the shrinkage rate and abrasion loss were reduced by 50% and 71.9% respectively. The weighted values of fluidity, compressive strength, flexural strength, stability, cohesiveness, and abrasion resistance were 0.422, 0.196, 0.196, 0.089, 0.058, and 0.039, respectively. A higher value of the comprehensive index generally denotes a better performance. The comprehensive index of SLM with 3.0% RP was the highest.     

Zweymüller双锥面螺旋臼联合PLUS-SL微创柄治疗股骨头坏死继发骨关节炎疗效分析

目的：探讨使用Zweymüller双锥面螺旋臼联合PLUS-SL微创柄治疗股骨头坏死继发骨关节炎疗效分析。方法：使用Zweymüller双锥面螺旋臼假体联合PLUS-SL微创柄治疗股骨头坏死继发骨性关节炎患者50例（58髋）。所有髋臼内衬均采用高交联聚乙烯防脱位内衬,陶瓷球头,随访10~32个月。结果：50例患者术后疼痛基本消失,双下肢长度差异平均（1.2±0.51）cm,术后Harris评分较术前显著增高（P〈0.01）。结论：Zweymüller双锥面螺旋臼联合PLUS-SL微创柄治疗股骨头坏死继发骨关节炎可以达到良好的恢复关节功能的临床疗效。