Use of waste marble powder and sirnak asphaltite ash as filler materials in concrete production

In this study, the effects of Asfaltite Fly Ash (AK) and Marble Powder (MT) on the compressive strength of concrete were investigated. Four different concrete mixes were prepared using C25/30 class concrete in the experimental work. This concrete class refers to concretes reaching approximately 25 MPa compressive strength at 7 days and approximately 30 MPa at 28 days. The study included four different mixes: Reference Concrete without additives (RB), concrete with AK additive (AKB), concrete with MT additive (MTB), and concrete with both AUK and MT additives used together (AMB). The additive materials were applied at rates of 5%, 10%, and 15% by concrete volume; a total of 60 samples were produced for each mix at the specified rates. All mixes were prepared as cube specimens of 15×15×15 cm and subjected to compressive strength tests after curing periods of 7 and 28 days. At the end of the 28-day curing period, water absorption tests and ultrasonic velocity measurements were performed. Water absorption values provided information about the permeability and durability characteristics of the concrete, while ultrasonic tests were used to evaluate microcracks and homogeneity within the concrete. Additionally, crystal structure and phase analyses of samples with 15% additive from RB and other additive concretes after 28 days of curing were conducted using X-Ray Diffraction (XRD), and microstructure characterization was performed with Scanning Electron Microscope (SEM) analyses. According to the results obtained, the average compressive strength of the RB mix was 28.37 MPa at 7 days and 33.64 MPa at 28 days. In AUKB mixes, compressive strength decreased as the additive ratio increased, with 28-day strengths measured as 27.28 MPa at 5%, 26.08 MPa at 10%, and 25.52 MPa at 15% additive. Increased water absorption values and decreased ultrasonic velocities in these mixes indicated reduced durability of the concrete. In MTB mixes, 28-day compressive strengths were 31.84 MPa at 5%, 30.70 MPa at 10%, and 27.84 MPa at 15% additive. Water absorption tests showed that low amounts of MT reduced concrete permeability, and ultrasonic test results indicated improved structural integrity of the concrete. In AMB mixes, 28-day strengths were found to be 24.67 MPa at 5% AK + 5% MT, 24.25 MPa at 10% AUK + 10% MT, and 21.79 MPa at 15% AK + 15% MT. High water absorption values and low ultrasonic velocity values in these mixes indicated negative effects on concrete durability. XRD analyses detected sharp and high-intensity peaks related to hydration products in RB concrete, while weakening of CSH peaks and deterioration of crystalline structure were observed in concrete with 15% AK. Concrete with 15% MT showed distinct peaks related to the calcite phase, and the crystal structure was preserved. In AMB concrete with combined AK and MT, the effects of both additives were balanced, providing moderate crystalline structural regularity. SEM analyses confirmed the dense and homogeneous structure of RB concrete. Samples with 15% AK showed increased xi microcracks and porosity, while samples with 15% MT exhibited dominant dense and large crystal structures and reduced void ratio. The AMB sample partially compensated for the negative microstructural effects of asfaltite due to the stabilizing effect of marble powder, but its bonding matrix remained weaker compared to RB. The findings show that using marble powder at low ratios in concrete mixes positively affects both mechanical strength and durability. Conversely, increasing the additive ratio of asfaltite fly ash adversely affects the strength and microstructural properties of the concrete. Additionally, the combined use of both additives did not fully improve the concrete properties. The study reveals that marble powder offers significant environmental and mechanical advantages as a concrete additive. Especially at 5% and 10% usage rates, marble powder additives positively influenced the compressive strength and durability of concrete, allowing it to reach the required strength level. However, mixes with asfaltite fly ash, 15% marble powder, or the combination of both additives showed decreases in compressive strength and durability properties, failing to reach the desired strength levels. These results suggest that using marble powder at low ratios can provide benefits to concrete mixes from both environmental and mechanical perspectives.