Study of Adding Cement to Hardened Powdered Novolac Resin Matrix for Manufacturing Novel Concrete in the Presence of Heat and Pressure

In this study, a new concrete has been manufactured by mixing powdered hardened novolac resin with cement in equal proportions and in the presence of heat (150-200) C and pressure (100 kN) as catalysts. The results of laboratory tests showed that the new concrete have a compressive strength of (92 MPa) and a density of (1761.1 kg/m ) while the compressive strength of the normal concrete at the age (28) days (25 MPa) and the density was (2368 kg/m). It can be seen from the images taken by the scanning electron microscopy that there is a correlation between concrete components (hardened powdered novolac resin with cement) in the presence of heat and pressure as catalysts (Bakelite concrete).


Materials and Methods
The

Results and Discussion
The compressive strength test was conducted for (100*100*100) mm 3 cubes to measure the compressive strength for each mix after (2 and 28) days.The strength values, which were obtained as the average of three cubes for each test, are shown in Table (1).The compressive strength value of the new concrete which has been manufactured by mixing the hardened powdered novolac resin, cement and heat with pressure as catalysts was ( 92MPa) while the density was(1761.1 kg/m 3 ) which give an indication that the cement is filling Conclusions 1-The compressive strength is higher than normal concrete.
2-Low density compared to normal concrete.
3-Through SEM images note correlation existence between crushed novolac resin hardened and cement this leading to an increase in the compressive strength.
of composite materials are low density, high specific strength and stiffness, good corrosion resistance improved fatigue properties, and low cost.Because of these properties, they have successfully replaced many conventional metals, polymeric composite materials, for example, can solve some of the problems resulting from the deficiencies of conventional steel-reinforced-concrete materials, and other polymeric materials in load-bearing structures in aircraft, automobiles, ships, pipelines, storage tanks, etc [2,3,4].Phenol formaldehyde (PF) resins are a large group of oligomers and polymers, which consists of various structures as resulting products from the reaction of phenol and formaldehyde.When the phenolic resins first introduction in the 1900s, they were primarily used in molding parts, insulating vanishes, industrial sheeting and coating.Later, phenolic resin were utilized as wood adhesives wood and fiber bonding to make composite.Despite the innovation of new type of thermosetting resins and other high-performance polymeric materials, phenolic resin still retains its important application in these areas and further to high-technological development especially in electronics and aerospace.This is due to the highly stable nature of phenolic resins with ultimate mechanical strength acquired during the curing process.Besides, they are inherently resisted against heat, flame and chemicals, which brings the application of PF resins to aerospace and transportation industry as thermostructural materials [5].Phenolic resins are synthesized from the petroleum-based phenol or substituted phenol with formaldehyde under either alkaline or acidic condition, which are known as resol and novolac PF resins, respectively [6].The novolac resins are produced under acidic condition with formaldehyde to phenol ratio of less than one.The first step in the novolac resin synthesis is conversion of formaldehyde (methylene glycol) in to hydrated carbonium ion under the effect of acid catalyst.The hydrated carbonyl compound then attacks the phenol molecule on its para-and or ortho-position to from the corresponding para-or ortho-benzylic ions with hydroxymethyl groups through dehydration reaction [7].Since hydroxymethly group on the benzylic ions are unstable in acidic condition, these hydrated benzylic ions further react with additional phenol and add to the free para-and ortho-sites on the phenol molecule by creating a methylene bridge between two phenolic aromatic rings [7].
Since reaction can happen at any of the three positions on each phenolic aromatic ring, the resulting novolac polymer acquires a complex structure with different polymer sizes and a molecular weight of up to (5000 g/mol).The reaction terminates as all the formaldehyde are consumed leaving with approximately (10%) of excess phenol, which can be remove along with water during the further distillation of the resin [8].The objective of the present study was to manufacture a novel concrete by mixing powdered hardened novolac resin with cement in equal portions in the presence of heat (150-200) 0 C and pressure (100 kN) as catalysts.
Fig. (1).Mold image in the presence of heat and pressure catalysts.
Fig.(3) SEM images of the new concrete which has been manufactured from hardened crushed novolac resin and cement in the presence heat and pressure as catalysts.[Bakelite concrete].