Materials Science Forum Vol. 1137

Abstract: This article discusses improving the low compression resistance of adobe houses in Saylla, Cusco, by incorporating fiberglass. It reviews studies employing synthetic materials and suggests adobe blocks with varying proportions of fiberglass. These adobe blocks to be studied will be produced in a traditional, regulated manner, with the addition of fiberglass at 0.10%, 0.50%, and 1.00%. Three samples of each type will be tested for reliable results. Compression tests show that traditional adobe fails to meet standards, while regulated adobe with fiberglass significantly enhances resistance. Adding 1.00% fiberglass results in a 123.20% increase in compression strength, reaching 1.634 MPa. The study concludes that fiberglass effectively strengthens adobe, providing practical applications for sustainable construction in Saylla, Cusco.

Abstract: This paper explores the production and properties of geopolymer cement mortar using laterite soils. The aim was to evaluate the laterite-based geopolymer mortars for masonry bedding applications. The testing programme encompassed three series of mixes tested to determine setting times, flowability, flexural strength and compressive strength. Two types of sands were used including standard sand and natural sand. The effect of water-to-laterite ratios, activating agent concentration, and cement-to-sand ratio were established. The properties of standard cement paste, and mortar were used as a reference. The study found that geopolymer mortar made from laterite meets the requirements for masonry bedding.

Abstract: The purpose of the current investigation was to lower the CO₂ footprint of an industrial self-compacting concrete mix, which currently consists of CEMI 42.5R solely, without any natural pozzolanas or supplementary cementitious materials. The target compressive strength of the industrial mix needed to exceed 55 MPa at 28 days of curing. In the present study we attempted a 20% reduction of CEMI 42.5R (by total mass of solids) by adding 20% of limestone filler and subsequently added 1% of colloidal nanosilica, aiming (i) at leveraging strength loss due to the reduction of Portland cement, (ii) at providing early strength and (iii) at enhancing the microstructure. A water to binder ratio of 0.42 was selected and superplasticizers were added. Fresh properties were studied in terms of slump-flow test, density and 1-day strength. In addition, the 28 day compressive strength was also tested, meeting the mix design strength requirement. Interestingly, the slump flow was improved, indicating better packing effect, however the compressive strength of the control formulations was higher than that of the nanoenhanced formulation. Further insights are also provided.

Abstract: The construction industry is crucial for social and economic development, but it faces sustainability challenges. About 40% of global industrial waste comes from construction, and cement contributes approximately 8% of global CO₂ emissions. This study aims to develop more sustainable materials by reusing waste and creating a new environmentally friendly binder, geopolymer, from ignimbrite (IG) from Arequipa, Peru, and metakaolin. Metakaolin from China (MKCh) and locally calcined metakaolin (MK650 and MK750) were used. The materials were characterized by XRD, FTIR, and SEM-EDS. Cylindrical geopolymers were produced with MK and IG ratios of 100/0 and 60/40, using a 9 mol/L NaOH activator solution. Curing was performed at 25 °C for 24 h, followed by 72 h at 50 °C. The results showed that the addition of IG increased the compressive strength, with the best performance observed in the MK-IG-60-40 material, with 52.72 ± 1.02 MPa. Thus, the addition of ignimbrite demonstrated to improve the strength of the geopolymers.

Abstract: Improper solid waste management in Lima, particularly glass, leads to severe environmental, social, and public health problems. The low recycling rate and waste accumulation contaminate soils and groundwater, impacting long-term quality of life. This research aims to evaluate the inclusion of residual glass powder (RGP) in concrete to enhance the sustainability of concrete design, focusing on San Juan de Lurigancho, where the highest amount of waste per person in Lima is generated. The proposed solution involves developing a waterproof concrete design by incorporating residual glass powder (RGP). This approach includes replacing 5%, 10%, and 15% of the cement in the mix to achieve a strength of 280 kg/cm², thereby reducing pollution from glass waste and CO₂ emissions. Fresh concrete properties were evaluated and found to improve flow and temperature. The slump of fresh concrete increased gradually with the percentage of residual glass powder (RGP), reaching up to 16.5%. Regarding the properties in the hardened state, in terms of strength, replacing 15% of the cement with RGP resulted in a 2.57% increase in compressive strength. The tensile strength at 28 days increased by 21.53% and 16.8% when replacing 10% and 15% of the cement, respectively. However, replacing 15% of the cement resulted in a 0.4% decrease in flexural strength, while a 10% replacement resulted in a 1.44% increase. On the other hand, replacing cement with 15% RGP reduced CO₂ emissions to 53.79 kg/m³. Additionally, a higher percentage of RGP in the concrete allows for cost savings of up to 12.2%, demonstrating a progressive reduction. From the analyses, it was found that the mix including 10% RGP stands out as the optimal option. It shows significant improvements in strength and profitability, reducing production costs by 3.4% and CO₂ emissions by 10.83%. This design achieves an ideal balance between performance, cost, and environmental sustainability.

Abstract: This study investigates the substitution of river sand with respect to fly ash in self-compacting concrete (SCC) and its performance on workability, strength, and durability. Various mix designs were assessed through L-box, V-funnel and slump cone test to determine fresh concrete properties. The results indicated that higher fly ash content significantly improved the passing and filling abilities of SCC, as evidenced by increased L-box blocking ratios and larger slump flow measurements, albeit with a higher segregation tendency. The mix with 75% fly ash and 25% river sand (FA75-RS25) demonstrated the best overall performance, showing superior passing ability (L-box ratio of 0.87), excellent filling ability (slump flow of 700 mm), and acceptable segregation resistance. This mix also achieved the highest split tensile, flexural, and compressive strengths, outperforming the control mix (FA00-RS100). Flexural strength results for the FA75-RS25 mix showed significant improvements over time, with values of 7.67 MPa at 28 days, 10.33 MPa at 56 days, and 11.17 MPa at 90 days, compared to the control mix which achieved 5.83 MPa, 7.50 MPa, and 8.17 MPa, respectively. These findings underscore the potential of fly ash as a viable and sustainable substitute for river sand in SCC, enhancing performance and supporting sustainable construction practices. Further research is recommended to explore additional mechanical properties and long-term durability aspects of fly ash-incorporated SCC.

Abstract: Currently, sustainable concrete alternatives are being sought without compromising the quality and compressive strength of conventional concrete. This article presents the development and results of an experimental study using recycled aggregates from foundations with an fc=280 kg/cm² and a novel additive of natural origin, oat husk ash, aiming to achieve concrete with adequate compressive strength and lower environmental impact. Specifically, the application of this additive as a partial substitute for cement in concretes made with construction and demolition waste (CDW) is analyzed. To determine the influence of this additive on compressive strength, standardized specimens were prepared with two types of concrete: (1) concrete with 30% CDW (C-30%CDW), and (2) concrete with 30% CDW and 5% oat husk ash as a partial substitute for cement (C-30%CDW-5%OHA). Finally, compressive strength tests were conducted at 7, 14, and 28 days on hardened concrete to verify the original hypothesis. The results show that oat husk ash positively influences compressive strength.