Smart Graphite–Cement Composites with Low Percolation Threshold

Abstract

The objective of this work was to obtain cement composites with low percolation thresholds, which would reduce the cost of graphite and maintain good mechanical properties. For this purpose, exfoliated graphite was used as a conductive additive, which was obtained by exfoliating the expanded graphite via ultrasonic irradiation in a water bath with surfactant. To obtain evenly distributed graphite particles, the exfoliated graphite was incorporated with the remaining surfactant into the matrix. This study is limited to investigating the influence of exfoliated graphite on the electrical and mechanical properties of cement mortars. The electrical conductivity of the composites was investigated to determine the percolation threshold. The flexural and compressive strength was tested to assess the mechanical properties. In terms of the practical applications of these composites, the piezoresistive, temperature–resistivity, and thermoelectric properties were studied. The results showed that the incorporation of exfoliated graphite with surfactant is an effective way to obtain a composite with a percolation threshold as low as 0.96% (total volume of the composite). In addition, the mechanical properties of the composites are satisfactory for practical application. These composites also have good properties in terms of practical applications. As a result, the exfoliated graphite used can significantly facilitate the practical use of smart composites.

Preparation of a novel foamed concrete modified with carbon fiber and graphite:

“…As can be seen from the previous article, the compressive strength of group C2 with 0.6wt.% carbon fiber is slightly higher than that of group O, proving that graphite is unfavorable to the compressive strength. This is because graphite is an inert material with poor cementing ability [34]. In the preparation process of the composite group specimens, we also find that the consistency of the cement slurry increases with increasing graphite content.…”

Preparation of a novel foamed concrete modified with carbon fiber and graphite: Mechanical, electro-magnetic and microstructural characteristics based on X-CT

“…Additionally, the compressive strength of group C2 with 0.6 wt% carbon fiber is slightly higher than that of group O, proving that graphite is unfavorable to the compressive strength. This is because graphite is an inert material with poor cementing ability [ 38 ]. In the preparation process of the composite group specimens, we also find that the consistency of the cement slurry increases with increasing graphite content.…”

Significance of Vibration Time in Developing Properties of Precast Pervious Concrete

“…The falling water head method was used to measure the permeability of pervious concrete on cylindrical samples with a diameter of 150 mm, and height of 150 mm using a self-made falling head system. The water permeability was defined by filtration coefficient k (mm/s) and calculated according to Equation (5).…”

“…Permeable pavements (PP) made of such materials as pervious concrete, porous asphalt, unit pavers, or granular materials are essential to reduce stormwater runoff, recharge groundwater supplies, and reduce the impact of the urban heat islands [4]. Unlike regular concrete modified in various ways [5], an open porous structure makes pervious concrete a particular type that allows water to flow freely through its structure. Pervious concrete has been successfully used for years in road and pedestrian water-permeable solutions in the U.S., Japan, Canada, and many European countries [6]-pervious concrete pavements allow quick and effective drainage of rainwater to the ground or an additional rainwater recovery system and enable cleaning and cooling of water during its flow through successive pavement layers.…”