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The validation of a feasible application for the production of sustainable bricks with local materials in humid and hot climates, which would allow the current housing needs of a constantly growing population with scarce economic resources to be met while also reducing energy inputs for climate control, is a current challenge without a definitive solution. Therefore, this research studied the incorporation of local aggregates and two second-generation materials to produce lime-stabilized Compressed Earth Blocks (CSEBs) using a semi-automatic machine for their manufacture. An initial matrix was designed as a baseline, and three more were developed with variations to incorporate second-generation materials individually and as mixtures. The stabilizer was added in concentrations of 5, 10, and 15%, resulting in a total of 12 batches of CSEBs. Eleven of the studied batches exceed the normative limits for simple compressive strength and initial water absorption coefficient. The best result of simple compressive strength was obtained in two batches of the same matrix that used construction demolition waste (CDW), reaching 4.3 MPa (43% above the minimum limit established by the most restrictive regulations and 115% above the least restrictive). It was possible to produce sustainable bricks in situ with average ambient temperatures of 32 °C and relative humidity of 91%. [ABSTRACT FROM AUTHOR]

The effect of different sintering parameters on the mechanical properties of sintered kaolin-GGBS will influence the variation of mechanical properties of sintered kaolin-GGBS geopolymer. Based on previous research, the samples have major cracking and many large pores due to the sintering temperature and holding time during the sintering process. The first objective is to study the effect of different sintering parameters on the mechanical properties of sintered kaolin-GGBS geopolymer and the second objective is to correlate the strength properties of sintered kaolin-GGBS geopolymer with microstructural analysis. In a solid-to-liquid 2:1 ratio, kaolin and GGBS were combined with an alkali activator. The kaolin-GGBS geopolymer was then cured at room temperature for 24 h. The samples were then cured for 14 days at 60 °C, followed by using double-step sintering at temperatures of 500 °C and 900 °C with varying heating rates and holding durations. The compressive strength and shrinkage of the kaolin-GGBS geopolymer were evaluated, and the morphology was examined using a scanning electron microscope. In comparison to other samples, the sintered kaolin-GGBS geopolymer with a heating rate of 2 °C and a holding duration of 2 h had the optimum compressive strength value: 22.32 MPa. This is due to the contribution of MgO from GGBS that refines the pore and increases the strength. The 13.72% shrinkage with a densified microstructure was also obtained at this parameter due to effective particle rearrangement during sintering. [ABSTRACT FROM AUTHOR]

Due to the current problems related to the generation of diverse wastes and the extraction of nonrenewable materials to be used in the construction sector, the alternative use of waste glass could be a sustainable option with environmental and economic benefits, in case of being feasible its use as a replacement of the usual aggregates to manufacture recycled mortars. In this research, one presents a study of the fresh-state properties of the mortars containing 15, 30, 60, and 100% recycled glass aggregates as a replacement for the usual aggregate, providing the experimental results of consistency, density, and air content. Using the experimental results, and by means of a numerical and statistical analysis of these, a diagram of triple interaction that allows us to unify the behavior of the studied properties is constituted; making feasible with this, the prediction of the behavior of these properties with respect to variables as their ratio water/cement, aggregate/cement, and different percentages of replacement of aggregates. [ABSTRACT FROM AUTHOR]

Chemical properties of geopolymers were evaluated from the reduction of fly ash particle size by grinding. X-ray diffraction determined that at early curing ages new crystalline phases appear in the matrix of the geopolymer and they remain for 28 days, with increases in intensities up to 60%. In Fourier transform infrared spectroscopy, displacements were identified in the main band of the geopolymers at higher wavenumbers, attributed to the greater rigidity in the structures of the aluminosilicate gel due to the increase of the reaction products in the geopolymers obtained through fly ashsubjected to previous grinding, which is observable in the geopolymers matrix. Results indicate that the reduction of fly ash particle size by grinding has an influence on the chemical properties of geopolymers. [ABSTRACT FROM AUTHOR]

At an international level, enormous volumes of construction and demolition wastes are generated: 170 million tons/year in the USA, 500 million tons/year in the European Union (EU) and 12 million tons/year in Mexico. Alternative uses for these heterogeneous materials, such as the manufacture of sustainable bricks, are potential solutions to this growing environmental issue. Based on previous studies, and in compliance with Mexican standards, four different types of secondary materials were utilized in the composition of a sustainable brick matrix. Temperature and solar radiation used for drying purposes were determined, as well as weight loss, resistance and initial maximum absorption. In order to characterize the resulting matrix, observations were made with a scanning electron microscope, and the chemical composition of the samples was determined by detecting basic compounds using mapping through SEM-EDS microanalysis, connected to the SEM unit. Finally, thermogravimetric analyses were performed to correlate mechanical and chemical behavior, and resistance to high temperatures of the mixtures. The results obtained showed that all-in-one (AiO) is the most appropriate material for brick manufacturing, Opuntia ficus-indica mucilage improves physical properties, such as increased compressive strength and reduced water absorption, while wood residues, clay minerals and illite enhance mechanical properties. [ABSTRACT FROM AUTHOR]

In the field of construction, sustainable building materials are currently undergoing a process of technological development. This study aims to contribute to understanding the behavior of the fundamental properties of concretes prepared with recycled coarse aggregates that incorporate a polyethylene terephthalate (PET)-based additive in their matrix (produced by synthesis and glycolysis of recycled PET bottles) in an attempt to reduce their high porosity. Techniques to measure the gas adsorption, water porosity, Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) were used to evaluate the effect of the additive on the physical, mechanical and microstructural properties of these concretes. Porosity reductions of up to 30.60% are achieved with the addition of 1%, 3%, 4%, 5%, 7% and 9% of the additive, defining a new state in the behavioral model of the additive (the overdosage point) in the concrete matrix; in addition, the porous network of these concretes and their correlation with other physical and mechanical properties are also explained. [ABSTRACT FROM AUTHOR]

Construction and Demolition Residues have become a complex-to-manage and expensive urban problem, so currently an environmental legislation is innovated in order to promote activities to mitigate it being the recycling one of the more accurate (it empowers the reintegration as second generation material for new use in construction). Considering the previous comments, some studies with mortars have been developed, where the natural aggregates are replaced by different percentages of residues, since there are not legislation or regulation that propose them. However, there are few investigations about the behavior of these concretes in fresh state, linked them with theirs properties in the posteriori hardened state. In this investigation, tests of properties in fresh condition (consistency, density and content of air) of mortars containing different percentages of recycled concrete aggregates as substitution of natural aggregates (10, 20, 30, 50 and 100%) and with different cement/sand rates (1:3.25, 1:4 and 1:4.74), have been realized. The results obtained show that mortars with recycled aggregates present a lower density, need more quantity of water to achieve the required consistency, and have higher air content than the reference mortars. [ABSTRACT FROM AUTHOR]

The difficult current environmental situation, caused by construction industry residues containing ceramic materials, could be improved by using these materials as recycled aggregates in mortars, with their processing causing a reduction in their use in landfill, contributing to recycling and also minimizing the consumption of virgin materials. Although some research is currently being carried out into recycled mortars, little is known about their stress-strain (&#963-ε); therefore, this work will provide the experimental results obtained from recycled mortars with recycled ceramic aggregates (with contents of 0%, 10%, 20%, 30%, 50% and 100%), such as the density and compression strength, as well as the &#963-ε curves representative of their behavior. The values obtained from the analytical process of the results in order to finally obtain, through numerical analysis, the equations to predict their behavior (related to their recycled content) are those of: σ (elastic ranges and failure maximum), ε (elastic ranges and failure maximum), and Resilience and Toughness. At the end of the investigation, it is established that mortars with recycled ceramic aggregate contents of up to 20% could be assimilated just like mortars with the usual aggregates, and the obtained prediction equations could be used in cases of similar applications. [ABSTRACT FROM AUTHOR]

Due to the environmental problem posed by the use of Portland cement as construction material, it becomes necessary the search for supplementary cementitious materials that mitigate the ecological damage caused by it. Because the chemical similarity and the high cementitious powers of the blast furnace slag, it is used in the generation of geopolymers in a cement total replacement. This research focused on the study of the influence of the curing conditions on the final properties of blast furnace slag establishing three variables: no cured process (N-C), cured of controlled temperature of 45°C (CT45-C) and room temperature cure (RT-C); evaluating the mechanical behavior until 28 days of age and the water porosity index. The results show that geopolymers based on blast furnace slag has a behavior similar to hydration maturity of Portland cement and curing process decreases the porosity; On the other hand, applying a controlled temperature generates densest resistant pastes such as the variable CT45-C which reach the highest value of resistance in all curing ages. [ABSTRACT FROM AUTHOR]

Due to the problem that represents the accelerated production of waste from the consumption of polyethylene terephthalate (PET), it becomes necessary to look for alternative solutions; chemical recycling is a suitable method for conversion into a material with potential application in concrete additive, such as unsaturated polyester resins; with the above improvements and conservation of non-renewable raw materials can reduce the environmental impact. This investigation was focused on obtaining the synthesis of a polymeric resin by the method of glycolysis, and their characterization by Infrared Spectroscopy (FT-IR); the results show that the recycled materials (PET and its processing) are similar to reagents made from primary materials so that it is considered feasible to use in the intended application. [ABSTRACT FROM AUTHOR]

The porosity of mortars with recycled ceramic aggregates (10, 20, 30, 50, and 100% as a replacement of natural aggregate) was evaluated and analyzed using three different techniques. The results of gas adsorption (N2), Scanning Electron Microscopy (SEM) image analysis and open porosity allowed establishing the relationship between the recycled aggregate content and the porosity of these mortars, as well as the relationship between porosity and the physical and mechanical properties of the mortars: absorption, density, compressive strength, modulus of elasticity, and drying shrinkage. Using the R2 coefficient and the equation typology as criteria, additional data such as Brunauer, Emmett, and Teller (BET) surface area (N2 adsorption) established significant correlations with the mentioned properties; with SEM image analysis, no explanatory relationships could be established; and with open porosity, revealing relationships were established (R2 > 0.9). With the three techniques, it was confirmed that the increase in porosity is related to the increase in the amount of ceramic aggregate; in particular with gas adsorption (N2) and open porosity. It was concluded that the open porosity technique can explain the behavior of these recycled mortars with more reliable data, in a simple and direct way, linked to its establishment with a more representative sample of the mortar matrix. [ABSTRACT FROM AUTHOR]

The construction sector generates 14,000 t/d of construction waste in Mexico City, these materials do not have real applications and end up accumulating in landfills. This work, the objective of which was to analyze the physicochemical and mineralogical properties of soil and construction waste used in the manufacture of Recoblocks, is divided in five stages. First, the excavation material was submitted to field tests. Physical and chemical tests were then carried out on construction waste. Subsequently, the optimal mixture for making Recoblocks was determined. Next, Recoblocks were evaluated and compared with blocks made with water only, without mucilage of Opuntia ficus, and finally a feasibility study was performed. The X-ray diffraction study showed the presence of plagioclase, minerals that improve bending resistance, hardness, durability, as well as resistance to stress in a material. Compared to blocks manufactured without mucilage, the use of Opuntia ficus mucilage increased the compressive strength of the material by 59%, as well as the erodibility. Recoblocks are an environmentally friendly option because they are based on recycled materials, dried under the sun, which eliminates the use of brick oven. The production cost per unit is just USD 0.19, so it is a viable option as a building material. [ABSTRACT FROM AUTHOR]

Studies of the elements that make up the structure of a building have generally focused on topics related to their physical and structural capacities. Although research has been carried out into environmental impact during the life cycle stages, the environmental profile is far from established. This research aims to reduce the gap in the knowledge of this subject, offering useful information to professionals in the construction industry, which will enable them to consider environmental aspects when choosing the best construction systems. The present study applies the methodology of the life cycle assessment (LCA), to analyze and compare four floor construction systems in two different scenarios ("A" with a functional homogeneous unit of 1 m2 and "B" with 1 m² made up of the percentages of the floor system and the special areas of the building). The analysis is performed using the LCA Manager software, along with the Ecoinvent 3.1 database and with a cradle to handover perspective (A1–A5). Comparison was made using two environmental impact methodologies, Eco-indicator 99 and CML 2001. The results highlight the stages A1–A3 as those that generate the greatest environmental impact. Comparing the environmental profiles of the different floor systems, one-way floor systems I and II had the best environmental scores, 30% less than two-way floor system III and 50% less than slab floor system IV. [ABSTRACT FROM AUTHOR]

Social Housing (SH) in Mexico has a potentially important role in reducing both the emission of greenhouse gases and the use of non-renewable resources, two of the main challenges facing not only Mexico but the planet as a whole. This work assesses the environmental impact generated by the embodied stages of a typical SH throughout its life cycle (cradle to grave), by means of a Life Cycle Assessment (LCA). Two types of envelope and interior walls and three types of windows are compared. It was found that SH emits 309 kg CO2 eq/m2 and consumes 3911 MJ eq/m2 in the product stages (A1 to A3) and construction process (A4 to A5); the most important stages are those referring to the products, namely, A1 to A3, B4 (replacement) and B2 (maintenance). Additionally, benefits were found in the use of lightweight and thermal materials, such as concrete blocks lightened with pumice or windows made of PVC or wood. Although the use of LCA is incipient in the housing and construction sector in Mexico, this work shows how its application is not only feasible but recommended as it may become a basic tool in the search for sustainability. [ABSTRACT FROM AUTHOR]

This study analyzes the effect of using waste by-products generated in the process of granite cutting as part of the granular structure of Ultra High Performance Concrete (UHPC). The manufactured concrete has a compressive strength greater than 115 MPa. This study substitutes 35%, 70% and 100% of the volume of micronized quartz powder (<40 μm) with granite cutting waste. This is an innovative study where the feasibility of using waste from granite quarries as a replacement for micronized quartz in UHPC has been analyzed. The results show an improvement in the workability and compressive strength of UHPC, for all substitution ratios. The flexural strength and tensile strength increase when the substitution ratio is 35%, and even the values obtained for 100% substitution are acceptable. In view of the results obtained in this study, granite cutting waste, instead of the micronized quartz powder usually used, is a viable alternative for the manufacture of expectedly more sustainable UHPC. [ABSTRACT FROM AUTHOR]

This research focuses on a comparison of 20 external wall systems that are conventionally used in Spanish residential buildings, from a perspective based on the product and construction process stages of the life cycle assessment. The primary objective is to provide data that allow knowing the environmental behavior of walls built with materials and practices conventionally. This type of analysis will enable promoting the creation of regulations that encourage the use of combinations of materials that generate the most environmentally suitable result, and in turn, contribute to the strengthening of the embodied stages study of buildings and their elements. The results indicate that the greatest impact arises in the product stage (90.9%), followed by the transport stage (8.9%) and the construction process stage (<1%). Strategies (such as the use of large-format pieces and the controlled increase in thickness of the thermal insulation) can contribute to reducing the environmental impact; on the contrary, practices such as the use of small-format pieces and laminated plasterboard can increase the environmental burden. The prediction of the environmental behavior (simulation equation) allows these possible impacts to be studied in a fast and simplified way. [ABSTRACT FROM AUTHOR]

Concrete is an essential material in the civil, architectural and buildings construction; however, its conventional production does not correspond to sustainable development. Today, dispense with its use is complex due to the current requirements of regulations, codes and construction techniques, which are based on its use almost exclusively, as well as by its successful implementation. Therefore, the study of alternative concretes that are more environmentally friendly with proposals to allow its application, is necessary. The aims of this research are the characterization of basic properties of aggregates originating from recycled demolition waste concrete pavements and analyze its feasibility in the use of recycled structural concrete (RSC). The results indicate that the recycled aggregate from pavements are lighter, porous and absorbent than natural aggregates (more accentuated in fine aggregates); despite this decrease in the quality of its properties, these can be regarded as an acceptable option in its use as aggregate for structural concrete (small loss of strength with contents less than 60%). [ABSTRACT FROM AUTHOR]