Experimental Evaluation of Concrete Blended with Eco-Friendly Bio-Sulfur as a Cement Replacement Material.

Bio-sulfur (BS), extracted from landfill bio-gas via microbial methods, was examined herein as a potential cement replacement material. The study developed five modified BS variants through limestone incorporation processes (sulfur-to-limestone ratios of 1:0.5, 1:1, 1:1.

Statistical Reliability Analysis of Ultrasonic Velocity Method for Predicting Residual Strength of High-Strength Concrete under High-Temperature Conditions.

Herein, we conducted a comprehensive statistical assessment of the ultrasonic pulse velocity (UPV) method's effectiveness in predicting concrete strength under diverse conditions, specifically early age, middle age, and high-temperature exposure. The concrete mixtures, with water-to-cement (W/C) ratios of 0.33 and 0.

Strength Prediction of Non-Sintered Hwangto-Substituted Concrete Using the Ultrasonic Velocity Method.

This paper presents and investigates the properties of concrete in which a portion of the cement is substituted with non-sintered Hwangto (NSH), a readily available building material in Asia. Given the inactive nature of NSH, this study aimed to determine the optimal cement replacement ratio and quantitative strength of the material. The unit weight, compressive strength, ultrasonic pulse velocity (UPV), and stress-strain of the NSH concrete (NSHC) were evaluated.

Evaluation on Early Strength Development of Concrete Mixed with Non-Sintered Hwangto Using Ultrasonic Pulse Velocity.

Currently, in order to reduce the greenhouse gases of global warming, research on alternative cement materials is being actively conducted in the construction industry to reduce cement use, and it is judged to be important to evaluate the timing of form removal for the initial age. Therefore, in this study, we evaluated the initial mechanical properties of concrete in which cement was partially replaced with non-sintered hwangto (NHT). Specimens without NHT (namely, normal mortar (NM) and normal concrete (NC)) and specimens with NHT (namely, non-sintered hwangto mortar (HTM) and non-sintered hwangto concrete (HTC)) were prepared.

A Study to Improve the Reliability of High-Strength Concrete Strength Evaluation Using an Ultrasonic Velocity Method.

The ultrasonic pulse velocity (UPV) technique, which is an efficient technique for concrete quality evaluation, can be affected by several factors. Many studies have proposed compressive-strength prediction models based on UPV in concrete; however, few studies have investigated the factors resulting in statistically different UPV results for different models. This study examined the difference between compressive strengths of various concrete specimens calculated by age-dependent and temperature-dependent UPV-based prediction models.

Investigating Ultrasonic Pulse Velocity Method for Evaluating High-Temperature Properties of Non-Sintered Hwangto-Mixed Concrete as a Cement Replacement Material.

Research on alternative cement materials is active worldwide, and in terms of fire safety, research on the evaluation of high-temperature properties of alternative materials is very important. Studies on concrete mixed with hwangto have been conducted by several researchers, but studies on high-temperature properties are lacking. Therefore, in this study, we evaluated the mechanical properties of concrete by partially replacing cement with non-sintered hwangto (NSH) at high temperatures.

Residual Compressive Strength Prediction Model for Concrete Subject to High Temperatures Using Ultrasonic Pulse Velocity.

This study measured and analyzed the mechanical properties of normal aggregate concrete (NC) and lightweight aggregate concrete (LC) subjected to high temperatures. The target temperature was set to 100, 200, 300, 500, and 700 °C, and W/C was set to 0.41, 0.

Correlation Analysis of Ultrasonic Pulse Velocity and Mechanical Properties of Normal Aggregate and Lightweight Aggregate Concretes in 30-60 MPa Range.

This study classified the strength of normal aggregate concrete (NC) and lightweight aggregate concrete (LC) into three levels (30, 45, and 60 MPa). In particular, the compressive strength, ultrasonic pulse velocity, and elastic modulus were measured and analyzed at the ages of 1, 3, 7, and 28 days to establish the correlation between the compressive strength and the ultrasonic pulse velocity and between the elastic modulus and the ultrasonic pulse velocity. In addition, this study proposed strength and elastic modulus prediction equations as functions of the ultrasonic pulse velocity.