Flexure behavior of Low-density reinforced concrete beams with different apertures under static loading

Figures & data

Table 1. Characteristics of coarse and fine-grained aggregates.

Description	Fine-grained aggregate (ESS 204)	Coarse-grained aggregate (ESS 205)
Density (kg/m^3)	1700:1900	2200:2500
Specific gravity (SG)	2.65	2.60
Absorption capacity (%)	2.5	3.0
Los Angeles abrasion value (mm)	25	40
Soundness (% loss)	5	10

Table 2. Physical properties of silica fume.

Properties	Description
Appearance (Color)	Dark grey
Appearance (Form)	Powder
Solubility	Dispersion into Water or Ethanol
Avg. Size (TEM)	≤1 nm
Specific gravity	1.7

Table 3. Details of the concrete mix.

Groups		G1	G2
MIX ID	units	Normal Concrete	Low-density concrete
Water (W)	kg	212.8	225
Cement (C)		380	400
Fine Aggregate (F.A)		680	300
Coarse Grained Aggregate (C.G.A)		1150	500
Zeolite Coarse (Z.C)		0	325
Zeolite Fine (Z.F)		0	100
Waterer/cement (W/C)	%	56	52
Sika163/Cement	%	0	2
Sika163	kg	0	8
Silica fume/Cement	%	0	10
Silica fume	kg	0	40
Heat Zeolite aggregate	c°	0	500
Average weight	gm	8157	6269
Average density	gm/cm^3	2.417	1.857
Rate of density and weight	%	Ref.	76.83

Figure 1. Stress strain curve of LDC and NC.

Table 4. Mechanical properties of LDC and NC.

Mechanical Properties	Symbols	Units	LDC	NC	Ratio (%)
density	ρ	gm/cm3	1.857	2.417	76.8
Compressive strength of cubes	Fcu	N/mm^2	44.27	45.55	97.2
Specified compressive cylinder strength of concrete	f’		35.42	36.44	97.2
Elastic modulus	Ec		29275.71	29695.93	98.6
Strain of concrete	εo	mm/mm	0.002419	0.002454	98.6
Uniaxial cracking stress	fctr	N/mm^2	3.99	4.05	98.5
Uniaxial crushing stress	fcur		44.27	45.55	97.2
Stiffness	S		27970.33	28371.8	98.6

Table 5. Dimensions and compressive strength of cubes and cylinders (LDC).

			Compressive strength				Average
	Dimensions (mm)		NC (MPa)		LDC (MPa)		NC (MPa)		LDC (MPa)
specimens	Cubes	Cylinders	Cubes	Cylinders	Cubes	Cylinders	Cubes	Cylinders
1	150*150*150	150*300	45.76	41.09	44.36	40.24	45.55	41.23	44.27	40.24
2			45.485	41.70	43.93	40.65
3			45.69	40.69	44.52	40.32
4			44.17	42.35	43.81	39.92
5			46.24	42.29	44.27	39.81
6			45.97	39.25	44.72	40.47

Figure 2. Apertures in the beams and reinforcement.

Figure 3. Detailing of RC-beams (LDC) with apertures.

Table 6. Specifications of specimens.

Groups	Specimens	Apertures (mm)	Concrete
Group (1)	NC	without	Normal
	B1–1		Low density
Group (2)	B2–1	25
	B2–2	38
	B2–3	50
	B2–4	60

Figure 4. Typical testing specimens of beams.

Figure 5. Zeolite aggregate concrete cube and cylinder after compression testing.

Figure 6. Setting up the experiment, concrete dimensions, and detailing of beams.

Figure 7. Compare between ultimate load capacity for specimens.

Figure 8. Comparison of mid-deflection between the specimens.

Table 7. Experimental results.

Specimens	Weight	Reduction Percentage weight	First crack				Ultimate load
			Pcr	∆cr	Ratio (%)		Pf	∆f	Ratio (%)
	kg	%	KN	mm	Pcr	∆cr	KN	mm	Pf	∆f
NC	145.01	Ref.	26	1.28	Ref.	Ref.	114.5	20.4	Ref.	Ref.
B1–1	111.41	23.17	25	1.174	3.85	8.28	109.3	19.9	4.5	2.5
B2–1	109.63	24.40	24	1.09	7.69	14.84	98.5	18.5	14	9.3
B2–2	107.24	26.05	21	1.07	19.23	16.41	96.8	18.1	15.5	11.3
B2–3	104.16	28.17	20	1.02	23.08	20.31	93.4	17.8	18.4	12.7
B2–4	100.94	30.39	19	0.957	26.92	25.23	90.8	17.4	20.7	14.7

Figure 9. Crack pattern of the normal concrete beam (NC - EXP).

Figure 10. Crack pattern of LDC Beam (B1–1 – EXP).

Figure 11. Crack pattern of LDC Beam (B2–1 – EXP).

Figure 12. Crack pattern of LDC Beam (B2–2 – EXP).

Figure 13. Crack pattern of LDC Beam (B2–3 – EXP).

Figure 14. Crack pattern of LDC Beam (B2–4 – EXP).

Figure 15. Calculate of ductility all specimens - determine (a, b).

Table 8. Calculate of ductility and stiffness for all specimens.

	Ductility (Du=b/a)				Stiffness(S)
	mm/mm				N/mm^2
	a	b					IE
Specimens	mm		Du	Ratio %	ELDC	ENC	IR	IA	IE	S=EI	Ratio %
NC	6	20.4	6	Ref.	-	29695.93	156250000	0	156250000	4.63999E+12	Ref.
B1–1	5.7	19.9	5.7	5.0	29275.71	-			156250000	4.57433E+12	98.58
B2–1	5.45	18.5	5.45	9.2				306796.15	155943203.9	4.56535E+12	98.39
B2–2	5.25	18.1	5.25	12.5				1637661.98	154612338	4.52639E+12	97.55
B2–3	5.15	17.8	5.15	14.2				4908738.52	151341261.5	4.43062E+12	95.49
B2–4	5	17.4	5	16.7				10178760.19	146071239.8	4.27634E+12	92.16

Figure 16. Compare between strain reinforcement for specimens.

Table 9. Values of tensile steel and strain concrete.

Specimens	Tensile strain		Strain of concrete
	(εs)	Ratio	(εs)	Ratio
	(mm/mm)	(%)	(mm/mm)	(%)
NC	0.0190703	Ref.	0.00279	Ref.
B1–1	0.0196759	3.2	0.00255	8.6
B2–1	0.0196759	3.2	0.00271	2.9
B2–2	0.0196759	3.2	0.00296	5.8
B2–3	0.0196759	3.2	0.00285	2.1
B2–4	0.0185295	2.8	0.00292	4.4

Figure 17. Compare between strain concrete for specimens.