# Mechanical, Electrical and Fractural Characteristics of Carbon Nanomaterial-Added Cement Composites
## 1 Introduction  
Cement composites are one of the oldest materials used in construction; their use dates back to 7000 BC [1]. Along with human civilization, cement composites have evolved significantly. Cement-composite materials have good resistance to corrosion, water, and temperature, along with economic advantages, making them one of the most suitable materials for construction. Currently, cement composites, such as concrete, are classified as quasi-brittle materials, meaning that they have relatively high compressive strength but low flexural and tensile strengths [2, 3]. Construction has advanced rapidly in modern times. In addition to being fast-paced, construction technology has evolved to possess high quality. Because cement-based composites are the most commonly used materials in construction, ongoing development and research are being conducted to improve their properties. The use of nanomaterials in cement composites is a new technology that is currently being researched and practiced in modern construction. Carbon nanomaterials (CNMs) are predominantly composed of carbon atoms [4]. They exhibit excellent electrical and thermal conductivity and high mechanical strength [4, 5, 6]. Carbon nanomaterials can be classified into carbon nanotubes (CNTs), carbon nanofibers (CNFs), and graphene according to their shape, dimensions, and nanostructural features [4, 5, 6, 7]. Graphene oxides (GOs), graphite nanoplatelets (GNPs), carbon dots, nanodiamonds, and fullerenes are examples of carbon nanomaterials. CNTs were first discovered in 1991 by the pioneer researcher [PERSON] [8]. CNTs are cylindrical carbon allotropes produced from graphene sheets [2, 9]. CNTs can be furtherclassified into multi-walled carbon nanotubes (MWCNTs) and single-walled carbon nanotubes (SWCNTs). SWCNTs have an exceptionally high tensile strength of 50-500 GPa and elastic modulus of 1.0 TPa [10]. MWCNTs exhibit exceptional characteristics analogous to those of SWCNTs. The tensile strength of MWCNTs ranges from 10 to 60 GPa. Their elastic modulus ranges between 0.3 and 1 TPa, while their electrical resistivity is between 5 and 50 \(\upmu\Omega\)-cm. Research has demonstrated that incorporating CNTs into cement composites positively influences various properties, such as compressive strength [11; 12; 13; 14; 15], flexural strength [11; 14; 16; 17], Young's modulus [15; 18; 19], tensile strength [13; 20], durability [21; 22; 23], fracture energy [24; 25], fracture toughness [24; 25; 26], electrical properties [27; 28; 29; 30; 15], and thermal properties [29; 31]. CNFs are quasi-one-dimensional nanomaterials with exceptionally high tensile strength, elastic modulus, and electrical and thermal conductivity [8; 16; 32; 33]. CNFs can exhibit elastic modulus values as high as 0.4-0.6 TPa, tensile strength of 2.7-7.0 GPa, and electrical resistivity of 55 \(\upmu\Omega\)-cm [10]. Numerous studies have demonstrated substantial enhancements in various properties, such as compressive strength [16; 33; 34; 35; 36; 37], flexural strength [16; 17; 36; 37; 38], Young's modulus [18; 37], fracture toughness [39; 40], fracture energy [40], durability [35], electrical properties [29; 41; 42], and thermal properties [29] of a cement composite. Graphene is a two-dimensional (2D) layer of covalently bonded carbon atoms [43] and an essential component of graphite, charcoal, carbon nanotubes, fullerenes, and other allotropes [44]. It has excellent properties, such as high thermal conductivity, high electrical conductivity, and high surface area [45; 46]. The use of graphene has been proven to significantly improve the compressive strength [44; 47; 48], flexural strength [47; 48; 49], Young's modulus [50], tensile strength [51], durability [52], fracture energy [24], and electrical properties [46; 48; 53] of cement composites. GNPs are two-dimensional platelets made up of stacked graphene layers [54; 55; 56]. They are characterized by low weight, planar structure, excellent mechanical properties, and excellent thermal and electrical conductivities [54; 55; 56].