An Investigation of Building Seismic Design Parameters in Mataram City Using Lombok Earthquake 2018 Ground Motion

An ultrasonic pulse velocity (UPV) test is often applied to determine the quality of concrete structures. It is well known that there are several factors which can influence the reading of ultrasonic velocity in concrete. One of the factors is the presence of steel reinforcement. Therefore, this paper is intended to evaluate the ultrasonic pulse velocity propagation either in plain or reinforced damaged concrete. A study on sound concrete is also provided as a comparison. Three mixes of concrete were provided, with 25 MPa, 35 MPa, and 45 MPa target compressive strengths. The specimens were 200x200x200 mm cube concrete specimens and 100x150x1100 mm reinforced concrete beam specimens. Each specimen was examined for velocity readings in sound and damaged concrete (25% and 50% of maximum load). In all concrete grades of both plain and reinforced concrete, the ultrasonic velocity decreases as the damage level increases. During intact conditions, the velocity of reinforced concrete is around 4.5% higher than that of plain concrete. However, damaged reinforced concrete has a lower velocity than plain damaged concrete. Furthermore, a new equation for predicting ultrasonic pulse velocity in reinforced concrete is proposed.

To support sustainable materials, the ordinary Portland cement production has been reduced since it left a high carbon footprint during manufacturing. As an alternative, the use of pozzolan Portland cement and composite Portland cement has been encouraged because they are more environmentally friendly. This paper examines some characteristics of cement made from pozzolan Portland cement (P.P.C.) and composite Portland cement (P.C.C.). The testing procedures were carried out on chemical and physical testing on P.P.C. and P.C.C. In addition, the mechanical testing of concrete made from both types of Portland cement and their combinations were conducted under compression load. Furthermore, the surface hardness of the concrete was evaluated using a rebound hammer measurement. Concrete testing was conducted after the curing age of 7, 28, and 42 days. According to chemical examination, P.P.C. has higher silica (SiO₂) and iron (Fe₂O₃) than those of P.C.C., whereas P.C.C. has a higher lime (CaO) content. Compared to P.P.C., P.C.C. shows faster initial and final setting time. This result is proportionally influencing the strength development of concrete. P.C.C. concrete offers significant strength development at an earlier age. Meanwhile, P.P.C. concrete reacts slower at an earlier age, but it improves the compressive strength at a later age. The mix combination of 50% P.P.C. and 50% P.C.C. in concrete shows the highest average compressive strength and surface hardness. This combination achieves the average compressive strength of 30.27 MPa, 35.27 MPa, and 35.93 MPa respectively for 7, 28, and 42 days curing time. Furthermore, this concrete also shows the most remarkable characteristics of Young's modulus and surface hardness