A Sustainable Approach Using Beef and Pig Bone Waste as a Cement Replacement to Produce Concrete

Abstract

Owing to the ongoing accumulation of industrial by-products, the management and disposal of waste have emerged as a significant issue. Employing these industrial wastes as an alternative to replace cement holds potential as a promising solution for conserving energy and reducing CO₂ emissions. In this study, pig and beef bone powder were used as cement replacements in concrete, and the mechanical properties were studied. Bone powders were prepared from random bones collected from local slaughterhouses, butchers, and restaurants. The pig bone powder (PBP) and beef bone powder (BBP) were prepared by direct fire contact, oven-calcined for 4 h at 300 °C, crushed, and sieved to size 0.4 to 2 mm. A concrete mix design was formulated for a target compressive strength of 21 MPa at 28 days of curing. This design included three different levels of cement replacement with each type of bone powder (10%, 15%, and 20% by mass). These mixes were then evaluated and compared to a control mix without any bone powder replacement (PB-0). This study evaluated the mechanical properties via compressive strength and flexural testing. The results showed that the workability of the mixtures decreased with the increase in bone powder content. Bone powder functions as a pozzolanic substance, engaging in a chemical reaction with the calcium hydroxide in concrete to produce compounds that exhibit cement-like properties; however, an increase in bone powder content worsened the mechanical properties. The most promising results were obtained for a 10% replacement percentage of BBP and PBP, obtaining strengths of 21.15 MPa and 22.78 MPa, respectively. These are both above the design strength, with PBP concrete even exceeding the strength of PB-0 (21.75 MPa). These results showed a good agreement with the standard values and allow to use these wastes as a replacement for cement, becoming a sustainable solution to the exploitation of quarry materials and, in turn, to the problem of contamination by biological waste from the meat industry.

1. Introduction

The construction industry is related to urban development and economic growth; however, this industry involves land deterioration, resource depletion, waste generation, and various forms of pollution to nature. Moreover, the construction industry is responsible for 10% of the total contamination by CO₂ emissions [1,2,3]. According to the European Environment Agency, the construction sector is one of the largest energy consumers in Europe, accounting for about 40% of total energy consumption [4]; overall construction waste generation has reached billions of tons around the world, and this trend has been increasing constantly [5,6,7]. This extensive resource use underscores the need for sustainable construction practices and efficient material usage to mitigate environmental impacts.

Construction materials significantly impact the environment throughout their life cycle, from extraction to eventual demolition. Among these, one of the most environmentally detrimental aspects is the processing of raw materials, particularly cement production. As the urgency to preserve environmental quality and protect human health increases, the construction industry is progressively focusing on the environmental aspects of their operations, products, and services [8]. Recent research has increasingly focused on producing sustainable construction materials that either minimize or entirely exclude cement [9,10]. Concurrently, studies have explored the incorporation of agricultural wastes, particularly the use of biomass ashes as pozzolanic agents in cement concrete or as alternative activators in geopolymer concrete, while preserving the fundamental properties required for construction materials [11,12]. Additionally, several authors have investigated the integration of natural fibers into cement to enhance its mechanical properties [13,14,15]. Recognizing cement’s critical role in construction, substantial efforts have been made to develop more sustainable cements [16,17] or alternative materials for replacement. Many researchers are focused on replacing a portion of cement with supplementary cementitious materials to decrease hazardous emissions [18,19]. In an effort to mitigate the environmental impact, various studies have proposed sustainable additions to concrete, aiming for eco-friendliness and sustainability. These include alternative concrete recycling methods and green concretes made from agricultural waste materials or compounds that require fewer non-renewable raw materials, such as sugarcane bagasse ash, rice husk ash, and palm oil fuel ash, which can reduce cement consumption while preserving the desired properties of cement [13,20,21,22,23,24,25]. A significant benefit of these new alternatives in construction materials is the reduction in carbon dioxide emissions, extended durability, and decreased energy consumption [26].

It is important not only to reduce the environmental impact but also to obtain materials that strike a balance between resistance, appearance, handling, and costs [27,28]. Among the most significant advances to obtain construction materials with lesser environmental impact are cement replacement with fly ashes, cement reinforcement with natural fibers and agro-industrial waste, and the recycling of construction waste [14,29,30]; all these options have demonstrated physical characteristics similar to those of conventional materials. The search for new materials to replace traditional raw materials makes the use of wastes an important research area. Any calcium-containing materials are potentially suitable in the production of cement replacements. One type of waste with a high calcium content is animal bones, which could be useful as a biologically and environmentally compatible raw material medium in the construction industry [31]. Calcined bones have a proportion of 44% calcium oxide, one the raw materials of Portland cement, which is one the most used cements in the construction industry.

There have been some works using waste bones. Naga et al. (2014) evaluated the use of waste fish bones to replace potash feldspar to produce stoneware; they found lower thermal expansion than for conventional tiles [32]. Onyelowe (2015) studied a bone ash admixture for land stabilization, and he found that the waste bone ash increased the compaction, making it suitable for any construction work including its use as a sub-base material for pavement construction [33]. Akinyele et al. (2016) used both bone and wood ash wastes for partial replacement of cement in concrete. They found that bone ash was a better pozzolana when compared to the wood ash and can partially replace cement in concrete [34]. Although the use of animal bone powders as a substitute for cement has been explored, with a predominant focus on cattle bone, the geographical area of our study presents a context characterized by significant pork consumption and pressing concerns about the disposal of pork bones. Therefore, this research aims to investigate and compare the mechanical properties of concrete made with pig or beef bone powder as cement replacement, thereby broadening the research scope within this field. This work evaluates the mechanical response of the cement in a concrete mixture for structural elements of 3000 psi resistance through the implementation of partial replacement with 10%, 15%, and 20% calcinated pig and beef bones.

2. Materials and Methods

Figure 1 illustrates a general process used for preparing the bone powder and samples. Each step of this preparation process is described in the following sections.

2.1. Materials for Concrete Preparation

Ordinary Portland cement (OPC) from Colombian local company was used in concrete preparation; the OPC was supplied by a local Colombian company and classified as UG (general use) according to NTC 121:2014 (NTC—Norma Técnica Colombiana) [35]. Sands supplied by a local hardware store were used as fine aggregate in the concrete mix. Coarse crushed stone aggregate, available at the local quarry, was collected as one of the ingredients for the concrete. Tap water free from salts, organic content, and turbidity was used for mixing and during curing.

2.2. Preparation of Pig and Beef Bones

In total, 25 kg of pig and beef bone waste was randomly collected from local slaughterhouses, butchers, and restaurants. The bones were manually cleaned using a scalpel and wire brush to remove residues of muscle, cartilage, and meat [36]. Subsequently, bones were immersed in 50% sodium hypochlorite solution for 24 h in order to remove impurities and dilute some of the blood and marrow residues (Figure 2).

After sodium hypochlorite immersion, the bones were subjected to two heating processes with the aim being to eliminate biological, fat, and water residues. When bones are exposed to a high temperature, they can exhibit morphological and color changes, turning from ivory white to brown and black, to different shades of gray and chalky white. These changes are related with the maximum temperature and time of exposure [37]. The first process was to place bones in a grill in direct contact with the fire (Figure 3a) in order to eliminate fat residues; in this step, bones were dried and obtained a brown hue (Figure 3b). After that, the cleaned and dried bones were oven-calcined for 30 h at an average temperature of 450 ± 5 °C. The temperature used in the oven was based on preliminary studies of calcined bones [34]; the time of exposure and temperature used allowed the bones to be easily crushed, obtaining a gray color like that of cement (Figure 3c).

Finally, the bones were crushed, milled in a conventional mill, and sieved to a particle size of 100 $\mu \mathrm{m}$ to obtain the powder that was used as a cement replacement (Figure 4).

2.3. Preparation of Test Samples

Samples were cast as per the mix design for 21 MPa (3000 psi) concrete with different dosages of bone powder as a cement replacement; this concrete was designed to meet the requirements of technical standard NSR10 [38]. According to the theory of concrete mix design [39], it is important to define the final use of the specimen; once the use is defined, it is necessary to consider the mix characteristics [40]. For this work, the mix characteristics were defined for concrete to be used in reinforced retaining walls, foundations, compacted pavements, lightly reinforced slabs, beams, and columns.

Table 1. Characteristics of concrete mix design.

Characteristic	Value
Workability	Medium
Consistence	Soft
Settlement [mm]	50–90
Fluency (%)	50–70

shows the characteristics for concrete design.

The water/cement ratio is one of the most important parameters in the concrete design and is a crucial factor influencing various aspects of concrete, including performance, workability, serviceability, durability, and crack control; it is also strongly related with the final properties of the concrete [41,42]. The water/cement ratio is calculated according to Equation (1):

$$\frac{W}{C}·ln ln \left(K_2\right)=ln ln \left(K_1\right)-ln (f^{\prime }cr)$$

(1)

where K₁ and K₂ are related with the compressive strength: for 20 MPa, $K_1=75$ MPa and $K_2=14.5$, and for 25 MPa, $K_1=90$ MPa and $K_2=13$. By extrapolation, we defined $K_1=78$ MPa and $K_2=14.2$ for a compressive strength of 21 MPa. $f^{\prime }cr$ is obtained from Abram’s equation (Equation (2)):

$$f^{\prime }cr\left(\mathrm{M}\mathrm{P}\mathrm{a}\right)=\frac{K_1}{{K_2}^{W/C}}$$

(2)

With $K_1$, $K_2$, and $f^{\prime }cr$ defined, the water/cement ratio was established using Equation (1), and it was obtained as 0.49.

2.3.1. Mix Proportions

The theoretical quantity of cement in the mix is defined following Equation (3), where s indicates settlement and TM is the maximum size of the aggregate. Once the water quantity is defined, the quantity of cement is established considering the water/cement ratio; however, the theoretical water and cement quantities need to be approached by mean correlations of humidity, settlement, and unitary mass according to the requirements of NTC396 and NTC1926 in order to obtain a mix with a better workability.

$$W=\frac{218.8 s^{0.1}}{{TM}^{0.18}}$$

(3)

A 3000 psi resistance concrete was designed; the material proportions and quantities are shown in

Table 2. Proportions and quantity values of concrete mix materials.

Cement/Sand/Coarse Proportions	Materials	Value
1:2:3	Cement (kg)	350
	Sand (m3)	0.56
	Coarse (m3)	0.84
	Water (L)	180

. From these values, the corrected water/cement ratio was established as 0.51; this is above the calculated value, demonstrating better mix workability in practice. The final design considered safety factors according to the use of the designed concrete [43].

2.3.2. Casting of Specimens

Pig and beef bone powder in proportions of 10%, 15%, and 20% were used as a cement replacement in the mix; a control specimen without bone powder was also cast in order to provide a comparison of the properties.

Table 3. Labels of specimens and mix proportions for cylinder samples.

Label	Cement (kg)	Sand (kg)	Coarse (kg)	Water (kg)	Beef Bone Powder (kg)	Pig Bone Powder (kg)
C-0	1.86	3.72	5.58	0.95	-	-
BBP-10%	1.67	3.35	5.02	0.85	0.19	-
BBP-15%	1.58	3.16	4.74	0.81	0.28	-
BBP-20%	1.49	2.98	4.46	0.76	0.37	-
PBP-10%	1.67	3.35	5.02	0.85	-	0.19
PBP-15%	1.58	3.16	4.74	0.81	-	0.28
PBP-20%	1.49	2.98	4.46	0.76	-	0.37

shows the mix proportions for each specimen. The specimens were cast in two types. The first group was cast as cylinders 150 mm in diameter and 300 mm in height; the second group was cast as beams with a size of $15\times 15\times 40$ mm. The specimens were labeled as BBP for those that contained beef bone powder as a replacement and PBP for those that contained pig bone powder; also, the control specimen was labeled as C-0. Table 3 and

Table 4. Labels of specimens and mix proportions for beam samples.

Label	Cement (kg)	Sand (kg)	Coarse (kg)	Water (kg)	Beef Bone Powder (kg)	Pig Bone Powder (kg)
C-0	4.10	8.2	12.3	2.09	-	-
BBP-10%	3.69	7.38	11.07	1.88	0.41	-
BBP-15%	3.49	6.97	10.46	1.78	0.62	-
BBP-20%	3.28	6.56	9.84	1.67	0.82	-
PBP-10%	3.69	7.38	11.07	1.88	-	0.41
PBP-15%	3.49	6.97	10.46	1.78	-	0.62
PBP-20%	3.28	6.56	9.84	1.67	-	0.82

show the specimen names and the proportions of compounds used in the mix for the cylinders and beams, respectively.

2.4. Testing of Specimens

All specimens were placed in a curing tank and were soaked in tap water. Specimens were removed after 7 and 28 days for different mechanical tests.

The beam specimens were used to determine the flexural strength of the concretes; specimens were placed in between two jaws for a three-point test, as shown in Figure 5b. For flexural strength, load was applied at a rate of 190 kg/cm²/min until complete failure of the specimen. The flexural strength testing was carried out following the specifications of the ASTM C78 standard [44].

The load that produced rupture of the beam was employed to calculate the modulus of rupture (MPa) following Equation (4):

$$MOR=\frac{Fl}{b{d}^2}$$

(4)

where

F = load (force) at the fracture point (N);

$l$ = length of the support (outer) span (mm);

$b$ = width (mm);

$d$ = thickness (mm).

The cylinder specimens were tested for compressive loading on the compression testing machine, as shown in Figure 4a. Specimens were placed between the two jaws of the compression testing machine, and the load was applied increasingly at a rate of 190 kg/cm²/min until complete failure of the specimen. The compressive testing was carried out following the specifications of the ASTM C39 standard [45]. The ultimate compressive load for each test specimen was recorded to find the compressive strength values of the concretes following Equation (5):

$$f_c^{\prime }=\frac{F}{A}$$

(5)

where

F = ultimate compressive load (N);

$A$ = area of each specimen (mm²).

Finally, the $f_c^{\prime }$ value was used to calculate the cracking stress; this value allows for correlation of the results with the modulus of rupture using Equation (6).

$$f_r=0.62{f_c^{\prime }}^{0.5}$$

(6)

2.5. Statistical Analysis

To compare the results on flexural strength and compressive strength between different samples, an analysis of variance (ANOVA) was carried out; the intervals were calculated to determine whether there were significant differences. Then, the Games–Howell test, which is a single-step multiple comparison, was performed using SPSS^® v.25 software (25, IBM Corp.©, Armonk, NY, USA) to locate these differences.

3. Results and Discussion

3.1. Compressive Strength of Concrete

An assessment of concrete’s fracture performance is a vital benchmark. Concrete typically undergoes deterioration due to cracks, and the presence of these cracks can lead to corrosion from harmful substances, directly impacting the safety and longevity of concrete structures [46]. According to the ASTM C39 standard, there are four types of well-defined fracture patterns under compression testing. Throughout the tests, all four types of fractures were observed. Figure 6 shows the compressive strength of concretes with bone powder as a cement replacement after 7 and 28 days of curing; BBP indicates specimens with beef bone powder, and PBP indicates those with pig bone powder. It was found that increasing the percentage of replacement affected the compressive strength with both replacements.

It was found that the best behavior in terms of compressive strength was with 10% replacement for both the beef bone powder and pig bone powder. However, 15% and 20% cement replacement showed reductions in compressive strength of 15% for beef bone powder and 23% for pig bone powder at 7 days compared with control concrete (Figure 6). This result confirms the findings of previous investigations that used pulverized cow bone [47], animal bone powder [48,49], and cattle bone ash [34]. These investigations agreed that the ideal percentage of cement replacement with animal bone powder is 10%. The compressive strength results obtained by these studies were variable, mainly due to the fact that they had different design strengths for the control. With the exception of [49] (20 Mpa), all the measurements for compression of cylinders with animal bone were above 21 Mpa, with percentages with respect to the control of between 84% and 114%, at 28 days of curing. In the present investigation, 97% and 105% were obtained for BBP and PBP, respectively.

After 28 days, it was possible to observe that concrete with replacement above 10% presented a reduction in compressive strength, and the value was lower than that of the control sample. Akinyele et al. (2016) attributed the gradual reduction in strength beyond the 10% replacement level to the excessive presence of calcium oxide in the mixture. This is due to the fact that calcium is the primary component of bone. However, it is interesting how 10% replacement with beef and pig bone powder produced a similar response to the control concrete. The values of compressive strength observed in this study closely align with those reported by Beka et al. (2019) and Varma et al. (2016), who investigated the use of bone powder ash as a partial replacement for cement [34,47,50].

This result suggests that bone powder could act as a cement replacement, and this replacement could be combined with fiber reinforcement to evaluate the mechanical properties and potentially obtain more eco-friendly concrete.

Concrete is a material that is mainly used in compression; therefore, this is its most relevant mechanical property and the criterion by which its quality is measured [51]. The fact that compressive strengths of 21.15 Mpa and 22.78 Mpa at 28 days were obtained for PBP and BBP concretes, respectively, is a significant finding, since this implies that there is a high probability that these mixtures, pending future complementary research, can be used in construction, for structural elements, and, of course, in non-structural elements or in mortars and plasters. The replacement of powder bone for cement maintains the values of compression resistance required by the Colombian Construction Code. The value for PBP concrete exceeds that of the sample without replacement, while BBP concrete has an average value near that of the control. Both results are above the design resistance (3000 psi), showing the potential use of these bone wastes as a cement replacement. Furthermore, in 2022, Colombia witnessed the slaughtering of a total of 3,107,462 cattle. Considering that the average weight of a cow at the time of slaughter is between 450 kg and 600 kg, and the bones constitute approximately 15% to 20% of this weight [52], it can be estimated that around 285,500 tons of bones were produced. This indicates a significant availability of this material.

3.2. Flexural Tensile Strength of Concrete

Beam specimens were utilized to determine the flexural strength using flexural tests. All specimens demonstrated failure within the central third of the beam, confirming the reliability of these tests. Figure 7 presents the maximum load sustained by concrete samples containing bone powder as a cement replacement, measured before failure at both 7 and 28 days of curing. The abbreviations BBP and PBP in the figure refer to specimens with beef bone powder and pig bone powder, respectively.

The maximum load in the flexural strength test allows for determining the modulus of rupture (MOR) of the specimens according to Equation (4).

Table 5. Parameters of each specimen used to calculate the modulus of rupture.

Label	Length [mm] (l)	Width [mm] (b)	Thickness [mm] (d)
C-0	513.1 $\pm$ 10.3	150.0 $\pm$ 0.5	154.4 $\pm$ 3.4
BBP-10%	510.1 $\pm$ 8.8	150.0 $\pm$ 0.5	157.3 $\pm$ 1.2
BBP-15%	511.7 $\pm$ 0.9	150.0 $\pm$ 0.5	156.5 $\pm$ 2.4
BBP-20%	512.5 $\pm$ 5.9	150.0 $\pm$ 0.5	156.3 $\pm$ 2.8
PBP-10%	518.5 $\pm$ 11.2	150.0 $\pm$ 0.5	156.5 $\pm$ 2.4
PBP-15%	515.3 $\pm$ 11.2	150.0 $\pm$ 0.5	153.3 $\pm$ 1.5
PBP-20%	517.4 $\pm$ 1.5	150.0 $\pm$ 0.5	154.3 $\pm$ 2.2

shows the results of the average parameters per sample involved in Equation (4), used to calculate the MOR; each parameter in Table 5 corresponds to three measurements, and Figure 8 shows the MOR values at 7 and 28 days of curing for different concrete beams.

The modulus of rupture is a direct measurement that is calculated when a load is applied on a beam, and it indicates the resistance of the concrete to flexion; however, before failing, the beam cracks. So, the values of cracking stress could validate the experimental method, because this cracking stress must have values similar to the MOR.

Table 6. Cracking stress $fr$ (Mpa) of cylinder samples at 7 and 28 days of curing. The reported standard deviation corresponds to the compressive strength $f_c^{\prime }$ values.

Label	${\mathit{f}}_{\mathit{r}}—7 \mathbf{D}\mathbf{a}\mathbf{y}\mathbf{s}$	${\mathit{f}}_{\mathit{r}}—28 \mathbf{D}\mathbf{a}\mathbf{y}\mathbf{s}$
C-0	2.22 $\pm$ 0.42	2.89 $\pm$ 0.79
BBP-10%	2.04 $\pm$ 1.50	2.85 $\pm$ 0.45
BBP-15%	1.78 $\pm$ 0.37	2.63 $\pm$ 0.33
BBP-20%	1.59 $\pm$ 0.40	2.48 $\pm$ 0.99
PBP-10%	1.95 $\pm$ 0.74	2.96 $\pm$ 0.90
PBP-15%	1.86 $\pm$ 0.91	2.60 $\pm$ 1.55
PBP-20%	1.74 $\pm$ 0.39	2.66 $\pm$ 1.81

shows the values of cracking stress, obtained using equation 6; the obtained values validate the experimental tests.

With regard to bending, the results for the modulus of rupture, as a function of flexural strength, obtained from the beam tests are good (2.18 Mpa and 2.54 Mpa); however, this is not a determining characteristic since the structural elements that work in bending, typically beams, are reinforced with steel to resist the tensile stresses generated by such bending.

Table 7. ANOVA test for compressive and flexural test results.

	Significance ANOVA		Variance Homogeneity
	F	sig	Levene Stat	df1	df2	sig
Compressive strength 7 days	14.201	0.001	1.817 × 1029	6	7	0.000
Compressive strength 28 days	10.465	0.003	1.440 × 1029	6	7	0.000
Flexural test 7 days	4.228	0.040	2.066 × 1029	6	7	0.000
Flexural test 28 days	11.897	0.002	3.591 × 1030	6	7	0.000

shows the ANOVA results for the compressive and flexural tests. Since the significance value is under 0.05, there are statistically significant differences between these mechanical results.

The results of the Games–Howell test for each treatment and each curing day allow for multiple comparisons and define the significative differences between them;

Table 8. Games–Howell results for the compressive strength at 7 days of curing.

Compressive_7 Days	C-0	BBP-10%	BBP-15%	BBP-20%	PBP-10%	PBP-15%	PBP-20%
C-0		1.93000	4.59500 *	6.22500 *	2.94000	3.82000	4.93500 *
BBP-10%	−1.93000		2.66500	4.29500	1.01000	1.89000	3.00500
BBP-15%	−4.59500 *	−2.66500		1.63000	−1.65500	−0.77500	0.34000
BBP-20%	−6.22500 *	−4.29500	−1.63000		−3.28500	−2.40500	−1.29000
PBP-10%	−2.94000	−1.01000	1.65500	3.28500		0.88000	1.99500
PBP-15%	−3.82000	−1.89000	0.77500	2.40500	−0.88000		1.11500
PBP-20%	−4.93500 *	−3.00500	−0.34000	1.29000	−1.99500	−1.11500

* Means statistical difference at 95%.

,

Table 9. Games–Howell results for the compressive strength at 28 days of curing.

Compressive_28 Days	C-0	BBP-10%	BBP-15%	BBP-20%	PBP-10%	PBP-15%	PBP-20%
C-0		0.60000	3.78500	5.74000 *	−1.02500	4.13500	3.34000
BBP-10%	−0.60000		3.18500 *	5.14000	−1.62500	3.53500	2.74000
BBP-15%	−3.78500	−3.18500 *		1.95500	−4.81000	0.35000	−0.44500
BBP-20%	−5.74000 *	−5.14000	−1.95500		−6.76500 *	−1.60500	−2.40000
PBP-10%	1.02500	1.62500	4.81000	6.76500 *		5.16000	4.36500
PBP-15%	−4.13500	−3.53500	−0.35000	1.60500	−5.16000		−0.79500
PBP-20%	−3.34000	−2.74000	0.44500	2.40000	−4.36500	0.79500

* Means statistical difference at 95%.

,

Table 10. Games–Howell results for the flexural strength at 7 days of curing.

Flexural_7 Days	C-0	BBP-10%	BBP-15%	BBP-20%	PBP-10%	PBP-15%	PBP-20%
C-0		0.22700	−0.37300	0.25200	0.07700	−0.16800	0.12700
BBP-10%	−0.22700		−0.60000	0.02500	−0.15000	−0.39500 *	−0.10000
BBP-15%	0.37300	0.60000		0.62500	0.45000	0.20500	0.50000
BBP-20%	−0.25200	−0.02500	−0.62500		−0.17500	−0.42000	−0.12500
PBP-10%	−0.07700	0.15000	−0.45000	0.17500		−0.24500	0.05000
PBP-15%	0.16800	0.39500 *	−0.20500	0.42000	0.24500		0.29500
PBP-20%	−0.12700	0.10000	−0.50000	0.12500	−0.05000	−0.29500

* Means statistical difference at 95%.

and

Table 11. Games–Howell results for the flexural strength at 28 days of curing.

Flexural_28 Days	C-0	BBP-10%	BBP-15%	BBP-20%	PBP-10%	PBP-15%	PBP-20%
C-0		0.53500	1.55000	1.64000	0.89500	0.78000	1.21500
BBP-10%	−0.53500		1.01500 *	1.10500 *	0.36000 *	0.24500	0.68000 *
BBP-15%	−1.55000	−1.01500 *		0.09000	−0.65500 *	−0.77000 *	−0.33500 *
BBP-20%	−1.64000	−1.10500 *	−0.09000		−0.74500 *	−0.86000 *	−0.42500 *
PBP-10%	−0.89500	−0.36000 *	0.65500 *	0.74500 *		−0.11500	0.32000 *
PBP-15%	−0.78000	−0.24500	0.77000 *	0.86000 *	0.11500		0.43500
PBP-20%	−1.21500	−0.68000 *	0.33500 *	0.42500 *	−0.32000 *	−0.43500

* Means statistical difference at 95%.

show the results of the Games–Howell test for the compressive (Table 8 and Table 9) and flexural (Table 10 and Table 11) test results.

Table 8 shows that in comparing the average compressive strength values at 7 days of curing, there was a significant difference, with a 95% confidence level, between the control mix and the 15% beef bone powder mix (BBP-15%) and 20% beef bone powder mix (BBP-20%), as well as the 20% pig bone powder mix (PBP-20%). These mixes exhibited lower compressive strength values compared to the control mix. For the remaining comparisons, no significant differences were observed, indicating that the average compressive strength at 7 days of curing among these mixes was statistically similar. This demonstrates that increasing the amount of bone powder in the mix reduces the 7-day compressive strength, with beef bone powder showing a decrease above 10% and pig bone powder showing a decrease above 15%.

Table 9 shows that when comparing the average compressive strength values at 28 days of curing, there was a significant difference, with a 95% confidence level, between the control mix and the 20% beef bone powder mix (BBP-20%). There was also a difference between the BBP-10% and BBP-15% mixes and the PBP-10% and BBP-20% mixes. For the remaining comparisons, no significant difference was observed, indicating that the average compressive strength at 28 days of curing among these mixes was statistically the same. Similarly to the previous test, this shows that increasing the amount of bone powder in the mix significantly reduces the compressive strength.

Table 10 indicates that when comparing the average flexural strength values at 7 days of curing, a significant difference was observed, with a 95% confidence level, only between the 10% beef bone powder mix (BBP-10%) and the 15% pig bone powder mix (PBP-15%). The PBP-15% mix showed greater flexural strength than BBP-10%. For the remaining comparisons, no significant difference was found, suggesting that the average flexural strength at 7 days of curing among these mixes was statistically the same. This demonstrates that the 7-day flexural strength did not show any significant difference among all the mixes.

Table 11 shows that when comparing the average flexural strength values at 28 days of curing, no significant difference was observed between the developed mixes and the control mix. Furthermore, the strength decreased when the percentage of bone powder, both beef and pig, was increased in the mixes.

The shaded cells are the values with a statistically significant difference. It is possible to see that the mechanical response of samples with beef and pig powder replacement did not present a statistically significant difference to that of samples without replacement; this means that the values maintain the standards for concrete compression at 3000 psi.

4. Conclusions

This study demonstrated that both beef and pig bone powders hold significant potential as cement replacements. Despite a slight reduction in mechanical properties beyond a 10% replacement level compared to those of the control mix, statistical tests revealed no significant differences, suggesting that the mechanical integrity of concrete incorporating bone powder remains within acceptable design resistance parameters. While the compressive response of these materials is promising for structural applications, expanded research into their long-term durability is necessary to fully understand and utilize their potential in construction.

The optimal performance In terms of mechanical properties for both pig and beef bone powder replacements was observed at a 10% substitution level, with pig bone powder demonstrating superior efficacy. The results indicate that an increase in the replacement percentage leads to a decrease in mechanical properties after 28 days of curing. Given the potential of using bone powder as a cement replacement, it is crucial to conduct an economic study to determine the associated costs of producing this novel material.

The modulus of rupture results for concretes modified with PBP and BBP yielded values of 2.18 mPa and 2.54 mPa, respectively. These figures fall within the recommended minimum tensile stress range of 10% to 15% of the compressive strength, suggesting the material’s suitability for use in structures subject to bending. However, future research should aim to further explore the flexural and tensile properties of concrete with partial BBP and PBP replacements. Methods like indirect tension tests on cylinders and beam bending experiments will be invaluable in confirming the findings of this study, particularly regarding the material’s performance in pavement slabs, sidewalks, and other structures where resistance to bending stresses is important.

The production of concrete or cement requires a large amount of energy for its manufacturing and handling. Opting for alternative construction materials such as bone powder allows us to reduce the amount of cement used, guaranteeing quality and generating sustainable options. Determining the exact energy required to produce and process bone powder varies depending on the method. Therefore, it is necessary to conduct new research to verify and compare whether using bone powder as a cement replacement results in energy consumption savings.