Composition effects on microstructure and mechanical performance of lightweight cementitious mortars incorporating recycled glass powder

One of the ways of lessening the CO2 emissions of cement industry consists of replacing clinkers with supplementary cementitious materials. The required service life of real construction elements is long, so it is useful to characterize the performance of these materials in the very long term. Here, the influence of incorporating waste glass powder as a supplementary cementitious material, regarding the microstructure and durability of mortars after 1500 hardening days (approximately 4 years), compared with reference mortars without additions, was studied. The percentages of clinker replacement by glass powder were 10% and 20%. The microstructure was studied using impedance spectroscopy and mercury intrusion porosimetry. Differential thermal and X-ray diffraction analyses were performed for assessing the pozzolanic activity of glass powder at the end of the time period studied. Water absorption after immersion, the steady-state diffusion coefficient, and length change were also determined. In view of the results obtained, the microstructure of mortars that incorporated waste glass powder was more refined compared with the reference specimens. The global solid fraction and pores volume were very similar for all of the studied series. The addition of waste glass powder reduced the chloride diffusion coefficient of the mortars, without worsening their behaviour regarding water absorption after immersion.

Characteristics, strength development and microstructure of cement mortar containing oil-contaminated sand

Study on the effect of WER and EVA on the performance and microstructure of cement mortars for a prefabricated residential floor

Effects of natural zeolite replacement on the properties of superhydrophobic mortar

An experimental investigation into the mechanical performance and microstructure of cementitious mortars containing recycled waste materials subjected to various environments

Recently, there has been a great effort to incorporate industrial waste into cement-based materials to reach a more sustainable cement industry. In this regard, the Bayer process of obtaining alumina from bauxite generates huge amounts of waste called red mud. Few research articles have pointed out the possibility that red mud has pozzolanic activity. In view of that, the objective of this research is to analyse the short-term effects in the pore structure, mechanical performance and durability of mortars which incorporate up to 20% of red mud as a clinker replacement. As a reference, ordinary Portland cement and fly ash Portland cement mortars were also studied. The microstructure was characterised through mercury intrusion porosimetry and non-destructive impedance spectroscopy, which has not previously been used for studying the pore network evolution of red mud cement-based materials. The possible pozzolanic activity of red mud has been checked using differential scanning calorimetry. The non-steady state chloride migration coefficient and the mechanical properties were studied too. According to the results obtained, the addition of red mud entailed a greater microstructure refinement of the mortar, did not worsen the resistance against chloride ingress and reduced the compressive strength compared to control binders.

This paper intends to analyze the performance of mortars with reactive MgO, as a sustainable alternative to cement. Six different MgOs from Australia, Canada, and Spain were used in the production of mortars as partial substitutes for cement, namely 5%, 10%, 15%, 20%, and 25% (by weight). MgOs with different levels of reactivity were used to analyze its influence on the performance of MgO mortars. In order to evaluate the mechanical performance of these mortars, compressive strength, flexural strength, dynamic modulus of elasticity, and ultrasonic pulse velocity tests were performed. Compressive strength tests showed that the use of 25% reactive MgO can cause a decrease of this property of between 28% and 49%. The use of reactive MgO affected the other mechanical properties less. This paper also intends to analyze the durability performance of mortars with reactive MgO. To that effect, water absorption by capillarity was assessed. In this research, the effect of using MgO on the shrinkage was also analyzed. It was found that shrinkage may decrease by more than a half in some cases.

Influence of assumed absorption capacity of superabsorbent polymers on the microstructure and performance of cement mortars

Effect of ethylene vinyl acetate on cement mortar – A review

To study the effect of the mechanical properties of silicon powder on cement admixture, the experiment was carried out, to investigate the consistency of mortar fluidity, breaking strength and compression strength test of the cement mortar samples with different dosage of silicon powder. The experimental results show that when the content of silicon powder is 0-4%, the consistency and fluidity of mortar can be improved, and the working performance of cement mortar can be improved; when the content of silicon powder continues to increase to 12%, the working performance of mortar decreases, but it still has good performance; when the content of silicon powder is 0-8%, the mechanical performance of mortar can be improved, if the content is too large, the compression strength and bending strength of mortar will be reduced, but It still plays a positive role in the strength of mortar.

Granite is extensively used in the construction industry; however, substantial solid waste is produced during production. This study focused on the feasibility of replacing cement with granite powder (GP) in cement mortar by investigating various properties, like consistency, water retention, density, setting time, compressive strength, and flexural strength, under different replacement rates. Scanning electron microscopy (SEM) is employed to study different replacement rates on the microstructure of cement mortar. Cement is replaced with GP at various rates ranging from 0%, 5%, 10%, 15%, 20%, 25%, and 30% in four strength grades of mortar (M5, M7.5, M10, and M15) to determine optimal parameters. Results indicated improved water retention, low density, and decreased setting time. Mortar consistency increased and decreased with increasing replacement rate, a maximum of 15%. Compressive and flexural strengths showed a similar trend with a maximum of 10% replacement rate. SEM images indicate that when replacement rates were less than 10%, the microaggregate and nucleation effects were dominant, producing denser mortar structures with reduced porosity. The rates exceeding 10% significantly reduced the binder material, leading to larger voids between aggregates and binder materials.

This paper investigates the influence of silica coated rubber on the performance of rubber mortars. A classical Stöber sol-gel method is applied to produce a layer of silica coating on rubber particles, which is used to partially replace the fine aggregates in concrete. The effects of the surface-modified rubber particles on the flowability, mechanical strength, capillary water absorption rate, and microstructure of mortars are examined. The results show that the silica coating on the rubber particles reduces the contact angle between the rubber particles from 120° to 103° (i.e., by 17°) and changes the hydrophobic properties from strong hydrophobicity to weak hydrophobicity. The mechanical strengths of mortars are significantly improved by the incorporation of surface-modified rubber particles, i.e., from 41.60% to 44.86% (compressive strength) and from 7.80% to 26.28% (flexural strength). In addition, the incorporation of surface modified rubber particles increases the density of the mortar’s microstructure and enhances the interfaces with its surrounding pastes.

The influence of the substrate type on the performance of an industrial cement mortar for general use

Early-age mechanical properties and microstructures of Portland cement mortars containing different admixtures exposed to seawater

The paper presents a study on the infl uence of ground waste glass cullet, introduced as a component of Portland cements in the amounts of 5% and 35% by mass, on the properties of pastes and mortars. The pozzolanic nature of the additive was confirmed – the long-term compressive strength of cement composites has incre-ased, compared to the reference sample. However, a decrease in the early compressive strength was observed. Replacing part of the Portland clinker with ground waste glass cullet resulted in the reduction of the heat of hydration. It was determined that the degree of grinding has a signifi cant impact on the activity of waste glass cullet – in the case of the cullet ground to 5000 cm2/g, the beginning of the pozzolanic reaction was observed after 7 days, whereas for the cullet ground to 3000 cm2/g, the reaction was severely delayed. In the course of one year, no negative impact of the alkali-silica reaction on the strength and microstructure of mortars and pastes was observed, however, a longer study needs to be conducted to verify the results. The research proves that waste glass cullet can be potentially used as a main component of Portland cements, with no adverse effects on the properties of the composites.