How do structural materials contribute to the stability and integrity of civil engineering projects? Describe the properties and behaviors of commonly used materials like concrete, steel, and timber in construction. Explain the role of material selection in ensuring structural durability, load$-$bearing capacity, and resilience against environmental factors such as seismic activity and weathering. Discuss the principles of material testing and analysis for assessing mechanical properties and structural performance. Furthermore, explore the advancements in material science and engineering techniques that enhance the design, construction, and maintenance of infrastructure, emphasizing sustainable practices and innovation in civil engineering materials.