Eco-efficient Construction Materials Research Articles

Nondestructive testing on concrete-based treated wastewater

Recycled wastewater in construction presents an opportunity to ease freshwater scarcity while advancing sustainability. This study investigated the influences of cement-type and treated wastewater source on setting time and mechanical properties of cement paste and mortar. Three cement types: ordinary Portland cement (CEM I), CEM III/A, and CEM IV/A-P, were encountered. Four plants treated wastewater versus potable water as control were included. Fifteen mixes were encountered; every 5 mixes addressed certain cement types along with specified treated water types. Two phases were designed: Phase I for pastes toe value setting time and Phase II for the mortar to evaluate the flexural and compressive strengths of tool 90 specimens, 6 at 2 and 28 days of age. The significant impact of both variables was observed. CEM III/A displayed the fastest setting among the other mixes, while CEM I was the slowest. Wastewater accelerated setting versus distilled water. The mechanical performance also varied based on the cement–wastewater combination. CEM IV/A-P provided optimal strength enhancement up to 50% in flexural and 35% in compressive strength with wastewater compared to CEM I control. Results were attributed to cement–water interactions influencing hydration and microstructure, while CEM I underperformed with wastewater, CEM III/A, and CEM IV/A-P benefits, especially at early ages. Considerable variability highlights the complex interplay of factors governing performance. Coupled chemical-microstructural analysis was recommended to elucidate underlying mechanisms. Overall, tailored cement–wastewater selection shows promise for sustainable concrete, pending further optimization and durability testing. The study provides a platform for context-specific development of eco-efficient construction materials utilizing locally available resources.

Exploring the different stages of treated wastewater on various cement types

Recycled wastewater in construction presents an opportunity to ease freshwater scarcity while advancing sustainability. This study investigated the influences of cement type and treated wastewater source on setting time and mechanical properties of cement paste and mortar. Three cement types, ordinary Portland cement (CEM I), CEM III/A, and CEM IV/A-P, were encountered. Four plants treated wastewater versus potable water as control. Fifteen mixes were encountered; every 5 mixes addressed certain cement types along with specified treated water types. Two phases were designed; Phase I evaluated setting time in pastes and Phase II evaluated the flexural and compressive strengths of mortar specimens at 2 and 28 days of age. The significant impact of both variables was observed. CEM III/A displayed the fastest setting among the other mixes, while CEM I was the slowest. Wastewater accelerated setting versus distilled water. The mechanical performance also varied based on the cement–wastewater combination. CEM IV/A-P provided optimal strength enhancement up to 50% in flexural and 35% in compressive strength with wastewater compared to CEM I control. Results were attributed to cement–water interactions influencing hydration and microstructure. While CEM I achieved low mechanical strength with wastewater; CEM III/A, and CEM IV/A-P benefits, especially at early ages. Considerable variability highlights the complex interplay of factors governing performance. Coupled chemical-microstructural analysis was recommended to elucidate underlying mechanisms. Overall, tailored cement–wastewater selection shows promise for sustainable concrete, pending further optimization and durability testing. The study provides a platform for context-specific development of eco-efficient construction materials utilizing locally available resources.

Improvement of the Mechanical Properties of Mortars Manufactured with Partial Substitution of Portland Cement by Kaolinitic Clays

Presently, the search for urgent solutions to mitigate climate change has become a global priority. One of the most important challenges is the characterization, standardization, and technology of sustainable natural raw materials, which will significantly improve the quality of common types of cement, the production process of which emits large amounts of greenhouse gases into the atmosphere. This work is focused on the study of natural kaolinitic clays (NKC) from the eastern part of the Iberian Peninsula and its main objective is to define and normalize their properties as natural pozzolanic materials. This research consists of an initial study to determine the morphological and chemical properties using SEM and XRF. Furthermore, the physical properties of the samples were studied, such as thermic treatment (TT), Blane particle finesse (BPF), real density (RD) and apparent density (AD), porosity (P), volume stability (VS) and start and final setting time (SFST). On the other hand, technological analyses were carried out as follows: chemical analysis (CATQ), pozzolanicity (CAP), mechanical compression strength tests at 7, 28, and 90 days (MCST) as well as the ultrasonic pulse velocity (UPV). XRF results indicated that the SiO2 content (49.9–51.0%) of kaolinitic clay in its natural state (NKC) increases to 57.41 and 58.10%, respectively, when calcined (CKC). The chemical analysis of pozzolanicity established that the NKC does not show pozzolanic activity during the first 8 and 15 days; however, once calcinated, its pozzolanic reactivity increases substantially. On the other hand, the results of the mechanical stress tests (MCST) indicate an exponential increase in mechanical resistance from 7 to 90 days, which is higher in mortars made with CKC; similarly, and according to the results of the calculation of the Resistant Activity Index (RAI), it shows that the substitutions of Portland cement (PC) by NKC are effective between the ranges of 10 and 25%, while in the case of the substitution of PC by CKC, all formulations (10, 25 and 40%) are effective. This research establishes that the kaolinitic clays of the east of the Iberian Peninsula can be considered quality pozzolanic materials, capable of partially replacing Portland cement. The results presented here could be used as guidelines for the understanding and application of natural pozzolanic materials contributing to the improvement of types of cement, mortars, and concretes, which would positively affect the quality and preservation of the environment as well as the sustainability of eco-efficient construction materials.

Optimisation of strength development of bentonite and palm bunch ash concrete using fuzzy logic

ABSTRACT This study presents green-concrete’s mechanical-properties modelling with cementitious portion replaced by PBA/BN ranging from 0-50% using fuzzy-logic. Incorporation of these admixtures in concrete encourages solid-waste derivatives utilization to achieve cost-effective and eco-efficient construction-materials which also mitigates environmental-degradation challenges due to CO2-emission during cement production and hydration. Assessment of the elemental-oxides inherent in the admixtures showed a good pozzolanic-activity with Al2O3+SiO2+Fe2O3 results of 74.75% and 72.03% for PBA and BN respectively. The maximum and minimum strength-responses were derived at 5%-replacement and 50%-replacement with experimental-results of 19.48-4.17MPa, 21.85-4.84MPa, 26.30-8.637MPa, 32.77-12.713MPa and 35.53-18.46MPa for 3-d,7-d,28-d,60-d and 90-d respectively. Fuzzy-logic technique was utilized to evaluate the strength development property of the green-concrete as it takes precisely into account the issue of vagueness of well-defined parameters to develop expert intelligent-model using Mamdani-FIS. The model’s performance was evaluated by using MLR-models, MAPE and RMSE. R2 of 84.905% and 99.1% was calculated for MLR-model and fuzzy-logic model respectively. RMSE and MAPE score of 2.406-2.14%, 6.5935-7.29%, 0.4183-4.62%, 0.2774-1.54%, 0.7544-2.06%, 0.4197-1.48% and 0.7912-1.66% were calculated for the initial and final setting-time, 3-d,7-d,28-d,60-d and 90-d concrete’s compressive-strength target responses respectively. The results obtained from the indicates better performance for the fuzzy-logic model in predicting the setting-time and mechanical-properties of PBA/BN-concrete.

Decarbonization and Circular Economy in the Sustainable Development and Renovation of Buildings and Neighbourhoods

In recent years, the building sector has been turning towards intervening in the existing city building stock. In fact, it is generally accepted that the refurbishment of buildings and the urban regeneration based on sustainability must form the axis of reformulation of the building sector. Nowadays, achieving sustainable urban development inevitably involves improving existing buildings, thereby preventing the need for city growth, and for the emptying of established neighbourhoods. Furthermore, considering the whole life cycle, it is well known the great amount of greenhouse emissions derived from the construction sector, so in order to reach a decarbonized society it is important to provide eco-efficient construction materials and solutions, adding the principles of circular economy and resource efficiency. The articles of this special issue show different aspects to be considered in order to reach a decarbonized and circular building stock.

Short sugarcane bagasse fibers cementitious composites for building construction

This paper presents an experimental assessment on sugarcane bagasse short fibers reinforced composites, conglomerated by Ordinary Portland Cement and Plaster and containing fine ash from rice husk combustion, for rural autonomous construction. The vegetable bagasse fibers were supplied directly from landfills of small rural sugar industries, smoked on site, washed in laboratory, treated in supersaturated calcium hydroxide at room temperature and dried before mixing. Physical and mechanical properties of components and composites were obtained. Accelerated aging of composites in CO2 rich atmosphere was done in laboratory, assessing the new properties of specimens after this aerial carbonation, in relation with the ordinary ones. Increasing of specific gravity, modulus of rupture, compressive strength, Young's Modulus, decreasing of porosity, water absorption and toughness of the aged composites was obtained. Their ability for building construction as sustainable and eco-efficient construction materials is analyzed.

Eco Efficient Construction Materials for Green Buildings

A green building is one which uses less water, optimizes energy efficiency, conserves natural resources, generates less waste and provides healthier spaces for occupants, as compared to a conventional building. There are now many tools and techniques for selecting construction materials that are less damaging to the environment.Use of natural materials that have low embodied energy and/or environmental impact, Timber (in preference to steel). Concrete reinforced with timber, bamboo or natural fibers. Building wastes, industrial wastes and recycled products. This paper addresses the case of materials for energy efficiency and materials capable of reusing a high waste content.

Approaching Green Buildings Using Eco-Efficient Construction Materials: A Review of the state-of-the-art

Approaching Green Buildings Using Eco-Efficient Construction Materials: A Review of the state-of-the-art