Abstract
Concrete specimens were made with standard portland cement, with river sand and gravel or expanded shale aggregate. Specimen A : Mixture C : S : G : 1 : 2.8 : 2.9 water cement ratio : 0.70 Specimen B : Mixture C : S : G : 1 : 1.9 : 2.0 water cement ratio : 0.45 with river sand and gravel Specimen D : Mixture C : S : G : 1 : 2.2 : 1.6 water cement ratio : 0.65 Specimen E : Mixture C : S : G : 1 : 1.3 : 0.85 water cement ratio : 0.40 with expanded shale aggregate Concrete specimens were tested in 5×10cm sizes for compressive strengths, static moduli of elasticity and ect, while heated to elevated temperatures. No loads were applied while temperatures were being raised, the testing being carried out upon reaching prescribed temperature levels. Typical stress-strain curves obtained by using these specimens are shown in Fig. 16 to 19. Test results obtained for four kinds of test specimens (A, B, C, D), compressive strengths, decrease in weight, deformation at rupture and energy of rupture, are shown in Fig. 20 to 23. Regarding compressive strength, 1) reduction is relatively great at 100℃ for both river gravel and expanded shale, 2) at 200 to 300℃ a slight strength incresae is seen, and 3) at 400℃ and higher the strengths drop again with the reduction in the case of expended shale being slightly smaller.
