In this paper, it was aimed to evaluate the effectiveness of four different types of filler materials with particle sizes below 63 μm in sustainable geopolymer mortars. For this purpose, 25%, 50%, and 75% limestone powder (LSP), basalt powder (BP), waste marble powder (WMP), and recycled aggregate powder (RAP) were substituted with river sand and 13 different mixtures including reference were obtained. Metakaolin was used as the main binder material, and sodium hydroxide/sodium silicate was used in a ratio of 1:2 as an activator. In addition, blast furnace slag was added to the mixture as a reaction accelerator at a rate of 13% of the amount of metakaolin. To determine the mechanical properties of the produced geopolymer mortars, compressive strength, flexural strength, splitting strength, porosity, ultrasonic pulse velocity (UPV), and abrasion tests were performed. Also, SEM and XRD analyses were performed to examine the microstructures of the specimens. The satisfactory results obtained proved that all four types of filler materials can be used in metakaolin-based geopolymer mortars. Optimum rates for limestone powder, basalt powder, waste marble powder, and recycled aggregate powder were obtained as 50%, 50%, 25%, and 25%, respectively.

This work covers some workability, mechanical, and durability properties of coloured self‐compacting concrete (SCC) containing maroon marble powder and iron oxide pigment. Pigments with varying amounts were used to produce coloured SCC. For this purpose, ten different series were prepared of which two of the series were pigment free that one of them was the colour of white SCC including limestone powder and the other one was the colour of maroon SCC including maroon marble powder. The other series were containing pigments with varying amounts. The water to binder ratio remained constant for all the series at 0.42. Slump flow, T50 time, V‐funnel, and L‐box tests were used to determine the workability of coloured SCC. The hardened properties that were determined included density, water absorption, ultrasonic pulse velocity (UPV), compressive strength, abrasion resistance, and impermeability. As workability, experimental results showed that coloured SCC could be obtained by using maroon marble powder and when iron oxide pigment used in amounts less than 6%. The addition of pigment notably increased the water absorption of SCC series. The use of smaller quantities of pigment caused slight increase in compressive strength. Higher pigment content also provided decreases in abrasive resistance, and after exposure to abrasion, mass losses were within the range of 0.89%–2.12% and the abrasion depths were within the range of 0.9 mm–2.1 mm. Among the varying amounts of pigmented series, M1 series which contains 1% pigment showed the best performance, and the findings indicated that it is possible to successfully utilize maroon marble powder and lower amounts of pigments in producing coloured SCC.

In this study, mechanical, durability, and microstructural properties of fiber-reinforced slag-fly ash-based alkali-activated concretes were investigated. Polypropylene (PP), steel (ST), and polyamide (PA) fibers were used, and the mechanical properties such as compressive, tensile, and flexural behaviour were investigated. High temperature and freeze-thaw tests were carried out within the scope of durability properties. High-temperature tests were conducted at 300, 600, and 900 degrees. Freeze-thaw tests were applied in 250 cycles. Microstructural analyzes were also carried out to understand the matrix composition of fiber-reinforced slag-fly ash-based alkali-activated concrete. The fibers have improved many mechanical properties, such as tensile and flexural strength. Existing building codes have shown consistent results in predicting the compressive strength of fiber-reinforced alkali-activated concretes at high temperatures. In addition, comparisons were made using existing building codes for splitting tensile strength and flexural strength, and new models were proposed.

In this study, it is aimed to investigate the influence of rice husk ash, which is a waste by-product of industrial production, on ultrasonic pulse velocity, compressive strength, flexural strength and high temperature endurance of the metakaolin-based geopolymer mortar. For this, the sand was substituted by rice husk ash (RHA) at the rate of 25%, 50% and 75% by wt. in the production of geopolymer mortar. A total of 4 series of metakaolin-based geopolymer mortars (reference series and three series with RHA substitution) were produced. In this study, the geopolymer, in other words, the binder of the mortar was produced by metakaolin and ground granulated blast furnace slag reacting with the mixture of sodium hydroxide (12M NaOH) and sodium silicate (Na2SiO3) solutions. The ratio of metakaolin and reactant mixture (12M NaOH + Na2SiO3) was determined for each series following the preliminary experiments. On the specimens produced as 50 mm cube and 40 x 40 x 160 mm prism, the intended experiments were carried out after specimens underwent curing in a dry oven at 60oC during 72 h and gained strength. The results showed that RHA could be used as a filling material in metakaolin-based geopolymer mortars, and metakaolin-based geopolymer mortars with 50% RHA substitution can be an alternative to the pure metakaolin-based mortar.

Alkali-activated composites are significant materials in reducing CO2 emissions and ensuring sustainability. With the increasing concerns about climate change globally, the interest in alkali-activated materials has also increased. Researching different fibers has very important potential in this area. This study aims to make alkali-activated concretes widespread in the concrete sector by using the materials common in conventional concretes and ensuring that alkali-activated concretes are an alternative in terms of sustainability. Experimental studies were conducted to examine the mechanical, durability, and microstructural properties (SEM) of slag-based alkali-activated concrete (AASC) reinforced with three various fibers. The fibers, polypropylene (PP), polyamide (PA), and steel (ST), were used with two ratios (%0.4 and %0.8 by vol.). Compressive, splitting tensile, and flexural strength tests were carried out at 28 and 90 days. In terms of durability properties, the samples were exposed to high temperatures (300–600–900 °C) and freeze-thaw test (250 cycles). The results showed that the addition of fibers improved the strength and durability properties; for instance, the existence of steel and polypropylene fibers increased the flexural toughness factor values by 430% and 260%, respectively. Moreover, the compressive strength of the fibrous samples exposed to 900 °C was obtained in the range of 6-23 MPa.