Impact of PEG400–Zeolite Performance as a Material for Enhancing Strength of the Mechanical Properties of LECA/Foamed Lightweight Concrete

Abstract

A versatile building material, foamed concrete is made of cement, fine aggregate, and foam combined with coarse aggregate. This study provides a description of how constant coarse aggregate replacement (50%) of LECA and foamed concrete, which are lightweight concrete types, by zeolite as a filler and PEG-400 as a plasticizer, water retention agent, and strength enhancer affect the mechanical properties of the cement. A study that examined the characteristics of cellular lightweight concrete in both its fresh and hardened forms was carried out for both foamed concrete and LECA concrete. In order to do this, a composite of zeolite and polyethylene glycol 400 was made using the direct absorption method, and no leakage was seen. Zeolite was loaded to a level of 10% and 20% of the total weight in cement, while 400 g/mol PEG was used at levels of 1%, 1.5%, and 2% of the cement’s weight. Various mixtures having a dry density of 1250 kg/m³ were produced. Properties like dry density, splitting tensile strength, and compressive strength were measured. An increase in the amount of PEG400–zeolite was seen to lower the workability, or slump, of both foamed and LECA concrete, while the replacement of aggregate by zeolite resulted in an exponential drop in both compressive and flexural strengths.

1. Introduction

The rapid construction of extremely tall buildings and large-scale, long-span concrete structures has led to extensive research into structural lightweight aggregate concrete (LWAC), which has been successfully produced and used in various forms of lightweight aggregate (LWA) in recent years [1,2]. With superior heat and sound insulation qualities, a low chance of seismic damage to a structure, a high strength/weight magnitude ratio, and less burden on the structural type and base, some advantages of employing structural lightweight concrete in the industry include reduced coefficient of thermal expansion, increased durability, and others. However, certain problems with LWAC’s engineering properties have prevented it from being widely used in the construction of load-bearing structural members [1,3,4]. For a given ratio and compressive energy, LWAC often has a higher brittleness than standard-weight concrete (NWC), but LWAC typically has lower mechanical residences [5]. Recently, numerous types of lightweight combinations with significantly higher mechanical qualities than traditional strength LWAC have been successfully used to create high-strength lightweight combination concrete (HSLWAC), which has a compressive strength of 50–100 MPa [5,6]. According to a study [3], compared to synthetic foaming agents, foaming agents made from the fundamental components of protein created more consistent foam with fewer air spaces. Ref. [3] carried out density and stability tests of foam, while [7,8] researched the manufacture and characteristics of aerated lightweight concrete. They discovered that protein-based agents worked well for density ranges of 500 kg/m³ to 1700 kg/m³. Foamed concrete is a slurry consisting of cement and plastic mortar that has foam particles mixed in. It is also known as reduced-density concrete, foamcrete, foam concrete, or cellular lightweight concrete [9]. The proper term for foamed concrete would be mortar rather than concrete because, for the most part, no coarse aggregate is utilized in its manufacturing [10]. Because it just contains cement and foam—no fine aggregate—it is sometimes referred to as “foamed cement” or “foam cement”. Foam concrete typically has a density ranging from 400 to 1600 kg/m³ [10,11]. Compared to clay bricks, foamed concrete is lightweight and extremely insulating [10]. Foamed concrete blocks can save on energy consumption from air conditioners, shipping expenses, labor costs, and foundation costs when utilized in place of clay bricks during building construction [10,11]. Good strength is also attained in comparison to regular building bricks. The ingredients of foamed concrete are a slurry of cement, fly ash or sand, and water [11]. By using lightweight aggregate [12], which can fill up to 50% of the FC matrix volume, the issue of obtaining low density and localized shrinking can be handled. Foamed glass grains are the lightest aggregate that works the best. Research on the manufacturing of foamglass granules and foamglass-ceramics has gained a lot of attention recently [12,13]. Foamed glass grains consist of closed cells that are spherical and hexagonal in shape [12]. Foamed glass’s low average bulk density, durability, frost resistance, and great mechanical strength are its distinguishing features [8,12]. However, there is a chance of alkali–silica reactions (ASR) when foamed glass is utilized in cement-based composites because it contains amorphous silica [8,10]. There are two ways to incorporate stable air gaps into the mortar [11]. One method involves prefoaming, while the other uses the mixed foaming approach [11,14]. The strength of the concrete is impacted by these air spaces, which lower its density [14]. The qualities of foam concrete can be greatly impacted by even little adjustments to any of the factors, including the type of mineral additive, water–binder ratio, and amount of foam employed [13,15].

Lightweight expanded clay aggregate, or LECA, is a flexible material with low density, high porosity, a natural pH of 7, and excellent heat tolerance (up to 1000 °C). These characteristics make LECA ideal for a variety of applications, particularly as a building material. Its historical use and dark brown hue emphasize its strength and aesthetic value even more [16,17]. Because of its porosity, LECA can hold onto moisture and form air pockets, which helps it float on water. Because the pores have the ability to absorb and hold onto pollutants, this special quality is also advantageous in environmental applications [18,19]. Materials resembling LECA date back to the ancient Mediterranean societies. Lightweight aggregates (LWA) are a diverse set of low-density materials used for a variety of civil engineering and building applications [20]. One subtype of LWA is LECA [17,18,20]. LECA is being used more and more in urban green infrastructure projects, such as thermally insulating concretes, permeable pavements, and green walls and roofs [20]. Globally promoted commercial trademarks include Go Green, LiaporTM, Stalite, Gravelite, Filtralite^®, and Danish Leca^®. In the early 1990s, there was a report on the first application of LECA as a CW substrate [20]. With a near-spherical shape and a water-resistant sintered ceramic matrix, LECA is a robust yet lightweight aggregate. LECA may absorb water up to 25% of its total weight, and its estimated cation exchange capacity is 9.5 cmol·kg [20,21]. The purpose of this work is to investigate the capacity of LECA to adsorb fluoride ions from tainted water, a capability that has not yet received much prior documentation [18]. The LECA utilized in this work was altered using magnesium chloride (MgCl₂) and hydrogen peroxide (H₂O₂) to improve its adsorption capacity [18,19]. The purpose of this change was to close a gap in the present environmental pollution management procedures by increasing the system’s efficacy in eliminating fluoride ions [17,21,22]. Aggregates come in two varieties: artificial and natural LWA (Lightweight Aggregate). Natural materials include riolite, perlite, LECA, vermiculite, volcanic tuffs, and lava slag [23]. The enlarged clay aggregates known as LECA are produced in a rotary kiln that is comprised of a long, large-diameter steel cylinder that is inclined at a slight inclination to the horizontal [23,24]. Refractory bricks are used to line the inside of the kiln in the firing zone [25]. As the kiln turns, the bricks heat up to the proper temperature and “roast” the clay pellets to allow for the necessary amount of expansion [21,22,23]. Cvk Chaitanya et al. [25] stated that, polyethylene glycols (PEGs) have been used to study self-curing self-compacting concrete (SCSCC). The impact on M30 grade SCSCC’s compressive strength is examined and contrasted with the same grade of SCC using the traditional immersion and dry curing techniques [25,26]. The compressive strength of specimens cured using Polyethylene Glycol–600 (PEG600) is shown to be quite good at 28 days, approximately 95% of the strength obtained through immersion curing; nevertheless, early age compressive strength of specimens is substantially lower than immersion treatment [21]. Materials with high capacities for P and N removal include limestone, biotite, muscovite, steel slag, and light-weight expanded clay aggregates. Microorganisms can use these substrates as electron donors to improve nitrification. Rich in mineral oxides of calcium (Ca), iron (Fe), and aluminum (Al), as well as compost and wood mulches (LECA) [20]. Certain substrates, such as clay bricks, fly ash, wollastonite, slag material, bauxite, shale, burnt oil shale, limestone, zeolite, and LECA, have been the subject of specific studies [16,20,24].

The addition of water to the overall formula H (OCH₂CH₂) nOH, where n is the average number of ox-ethylene groups with an average value of (4 to 180), results in polyethylene glycol, an abstract form of the polymer ethylene oxide [27,28]. Self-curing agents are widely applicable to mass concrete, lightweight concrete, self-consolidating concrete (SCC), and high-performance concrete (HPC) [27]. Many chemical agents, such as poly-valent alcohol, which is available from the group that comprises DI-propylene glycol (DPG), propylene glycol (PG), and polyethylene glycol (PEG), can be used to produce self-curing concrete [27,29], butylene glycol, sorbitol, xylitol, neopentyl glycol (NPG), and glycerin; on the other hand, phytosterols, polyoxyethylene (POE), sodium pyrrolidone carboxylate (PCA-Na), hyaluronic acid, stearyl alcohol, acetyl alcohol, or polyacrylic acid can be added to concrete as supplements [28,30]. Chenchen Kuai et al. [31] stated that, Due to the high internal temperature in the summer, deformation-related clogging of open-graded friction courses (OGFC) is common. Summertime OGFC temperature reductions have a major positive impact on reducing rutting and clogging issues [31]. OGFC was modified using a phase change composite material (PEG/SiO₂), which contains SiO₂ as the shell and PEG4000 as the core. Various mechanical performance tests were carried out, and the findings indicated that the PEG/SiO₂ combination has very minor detrimental effects [31]. An indoor heating test conducted on slab specimens with varying PEG/SiO₂ doses and moisture conditions in a lab setting was then used to show the efficacy of the PEG/SiO₂ modified OGFC for pavement temperature regulation [28,31].

1.1. The Applications of Lightweight Concrete in Architecture Facades

Because LWC is ecologically less thermally conductive than NWC, it can contribute significantly to energy savings when used as insulation. Stated differently, employing LWC manufactured with regulated thermal characteristics reduces the energy used for air acclimatization in both warm and cold regions [32]. Energy scarcity issues have been becoming worse recently and are now a major concern for the entire world. Another advantage of LWC is that it can be produced using a lot of industrial and agricultural waste, which is both cost-effective and environmentally beneficial [32,33]. Instead of using “Infra”, several researchers use “Ultra”. In the Netherlands, warm concrete, or “warmbeton”, is referred termed as such because of the elevated warmth that results from the hydration process [13]. In summary, the state-of-the-art concrete in terms of density and insulating qualities is known as Infra lightweight concrete (ILC), ultra lightweight concrete (ULWC), or “warmbeton”, which categorizes concrete with a density of less than 800 kg/m³ [32,34]. The mechanical and thermal characteristics of ILC, LWC, and NWC, respectively, can serve as the foundation for a sensible and cost-effective building architecture with comparatively low energy consumption: Perfectly insulated ILC is best suited for load-bearing façades; moderately strong and insulating LWC is excellent for floor slabs; and highly insulating but poorly insulated NWC is appropriate for vertical internal parts like columns and shear walls [32,35].

Insulating lightweight concrete’s (ILC) manufacturing, strength, and thermal characteristics have all significantly improved in recent years [32]. Different multi-layer insulation system types are shown in Figure 1, together with their thermal characteristics in comparison to ILC [32]. Also, for example, a family home in Berlin’s outside walls were built in 2007 using the mix showed in Figure 2 [32].

Recently, ULWC, or ultra-lightweight concrete, has been presented as a unique building material that combines load-bearing capacity with moderate thermal insulating qualities [34]. Its planned application as a monolithic building envelope combines the best features of lightweight and heavyweight construction to offer new directions in building physics [34,36]. The potential of ULWC building envelopes for thermal comfort and energy efficiency were examined [34]. Using EN-ISO 13786 [37] calculation methodologies, the dynamic thermal properties of a ULWC structure were initially compared with conventional constructions [34,37]. By offering a well-rounded solution for comfortable and energy-efficient living spaces, ULWC has the potential to revolutionize existing construction methods by providing excellent insulation while preserving structural integrity. These comparisons are meant to demonstrate these benefits [34,37].

Overall, Fair-faced concrete monolithic constructions are incredibly robust in addition to having great architectural potential [38]. Recycling is made simpler and costs are reduced because plaster and cladding are not required [34,39]. Regrettably, monolithic fair-faced concrete buildings have all but vanished in colder nations like Germany due to the high heat conductivity of normal concrete (NC) [39].

1.2. Research Methodology

The research aims to investigate the impact of incorporating PEG400-zeolite on the mechanical properties of LECA/foam lightweight concrete. The methodology section outlines the systematic procedures and techniques that will be employed to achieve this objective.

Firstly, many earlier studies that examined the same materials under various conditions were reviewed in the introduction section. These studies focused on identifying the most significant benefits and drawbacks through modification and investigating the benefits in the current field of study. Additionally, the significance of these materials was discussed in relation to both the architectural and construction aspects. Secondly, it goes over the study’s materials (Lightweight Expanded Clay Aggregate (LECA), Cement, PEG 400, Zeolite and Water) and highlights the key traits that could have an impact on the many values that will be assessed by the tests. There was also discussion about the design of the concrete mixtures utilized in the research issue and the testing that will be carried out in compliance with different international codes. Thirdly, the significance, benefits, and drawbacks of the materials utilized were examined in order to assess whether or not they are promising materials for use in the building industry. These tests will be carried out to measure the previously defined values. Finally, the outcomes of the tests that had been previously presented were examined, together with the benefits and efficacy of the materials that had been used.

The methodology outlined above aims to comprehensively assess the impact of PEG400-zeolite on the mechanical properties of LECA/foam lightweight concrete. Through systematic experimental design, rigorous testing, and detailed analysis, this research seeks to advance the understanding of material enhancements in lightweight concrete and contribute to the development of more durable and sustainable construction materials

2. Materials and Mix Proportion

2.1. Cement

Cement is a type of bonding medium that possesses both cohesive and adhesive properties. These properties enable it to bind various construction materials together to form compact assemblies. One of the most popular varieties of Portland cement is ordinary Portland cement. 42 grade Ordinary Portland Cement was utilized in this study. It is examined whether the 42-grade ordinary Portland cement utilized complies with ECP-203 [40]. The parameters of the cement utilized in the research are listed in

Table 1. Characteristics of cement.

Properties	Worth
Finess	4.7%
Consistency	35%
Specific gravity	2.9
Initial setting time	31 min

below.

2.2. Natural Fine Aggregate

The fine aggregate in this case was natural river sand with a maximum size of 4.65 mm and a fineness modulus of 1.95. River sand had densities of 2588 kg/m³. The physical, mechanical properties of aggregate could be viewed as in

Table 2. Natural aggregate’s mechanical and physical properties.

Properties	River Sand
Specific gravity	2.59
Volume density	1614
Crushing value %	-
Water absorption%	1.84
Los Angeles abrasion %	-

.

2.3. Expanded Polystyrene Foam [EPF]

Expanded Polystyrene Foam (EPF) is a white thermoplastic made from petroleum that has closed pores and is in the form of foam. The weight and dimensions of the [8–10] × [8–10] × [8–10] mm EPF samples were measured in this investigation.

Table 3. Properties of Expanded Polystyrene Foam.

Properties	Worth
Density (kg/m3)	10
Thermal Conductivity (W/mK)	0.0372
Compressive Strength (MPa)	0.127
Volume (mm3)	(560–1000)
Unit weight (kg/m3)	9.56

provide the measured parameters, volume, and unit weight variations. Materials that were used and discarded as packing material are the EP foams used in the studies. To enable the waste EP foams to pass through a screen with a 10 mm mesh size, they were gathered, crushed, and the grain size was reduced to 8–10 mm (Figure 3).

2.4. Lightweight Expanded Clay Aggregate [LECA]

After being weighed without water, the LECA aggregate was submerged in water for several days. The aggregate was placed on a sieve to allow any excess water to drain off around 30 min before mixing. In contrast, the LECA aggregate was employed without any prior soaking with specific gravity 2.21 and density 574 kg/m³. The tests for coarse aggregate (LECA) are performed in accordance with ECP Committee [40]. LECA obtained from BGN company-Egypt is used in the present work. The physical Properties of the self-curing agent LECA given by are shown in

Table 4. Properties of LECA.

Properties	Value
Specific gravity	2.21
Finess modulus	1.27
Bulk density (kg/m3)	574
Water absorption	18%

. Image of the LECA is shown in Figure 4.

From previously literature, an illustration of three distinct LECA kinds is shown in Figure 5 beside a structural LC. Defined voids between the aggregates that remain in the structure after compaction are what define LECA [35].

The reviewing size dissemination of EPF is introduced in Figure 6, comparing with natural coarse aggregate for more vision. Also, the reviewing size dissemination of LECA is introduced in Figure 6, comparing with same natural coarse aggregate for more vision.

2.5. Polyethylene Glycol [PEG-400]

One of the most widely used water-soluble polymers is PEG-400, which also dissolves in a variety of organic solvents, such as aromatic hydrocarbons. In concrete mixtures, adhesives, binders, and soldering fluxes, PEG-400 is utilized as a plasticizer to speed up lubricity and workability and acts as a water retention agent among other precise distribution properties. Polyethylene glycol has characterized by a numerical suffix of groups with specified average molecular weights. PEG is available in a different range of molecular weights from 300 g/mol to 1 × 10⁷ g/mol. The PEG-400 obtained from Desert chart company-Egypt is used in the present work, with 400 g/mol. The Properties of PEG-400 given by are shown in

Table 5. PEG-400 Properties.

Properties	Value
Molecular weight (g/mol)	400
Density (gm/cm2)	1.117
Appearance	Liquid
Specific gravity	1.11
Hydroxyl value	310
Nature	Water-Soluble

. Image of the PEG-400 is shown in Figure 7.

2.6. Zeolite

Zeolite was obtained with the following specifications: specific gravity of 2.15 g/cm³, volumetric weight of 1.083 g/cm, specific surface area of 6150 cm²/g, and soundness of 1 mm. Figure 8 depicts the distribution of Zeolite particle sizes comparing with cement particle sizes. It is significantly lighter than Portland cement and has an off-white color.

Table 6. Chemical composition of Zeolite.

Oxides	Value
Na2O	0.66
MgO	0.02
Al2O3	1214
SiO2	64.79
P2O5	0.08
SO3	0.55
CI	Nil
K2O	3.21
CaO	3.6
TiO2	0.44
MnO	Nil
Fe2O3	4.06

displays the chemical composition of zeolite. Figure 8 depicts the distribution of cement particle sizes.

2.7. Water

Concrete’s freshwater qualities eliminate flavor, color, and smell.

2.8. Mix Design

The water-binder ratio, sand-binder ratio, and dry density were designed to be 0.45, 1:1.5 and 1250 kg/m³ respectively. The experimental program was aimed to investigate the strength of light weight concrete by adding poly ethylene glycol PEG400 @ 1%, 1.5% and 2% by weight of binder to the concrete. Also, this study describes the process of continuously replacing 50% of the coarse aggregate in LECA and Foamed concrete. The following fourteen light weight mixes were created as a partial replacement for cement content in the Zeolite. The percentages of the mixes are 25% and 50%.

Table 7. Lightweight Foam concrete (LWFC) and Lightweight LECA concrete (LWLC) mix proportion.

		Binder
Mix Id	Target Density	Cement	Zeolite	Sand	Water	Foam	LECA	PEG-400
	(kg/m3)	(kg/m3)	(kg/m3)	(kg/m3)	(kg/m3)	(kg/m3)	(kg/m3)	(kg/m3)
F-CM	1250	465	-	698	210	23	-	-
L-CM	1250	465	-	698	210	-	23	-
F-1PZ10	1250	465	46.5	698	205.35	23	-	5.11
F-1.5PZ10	1250	465	46.5	698	203	23	-	7.67
F-2PZ10	1250	465	46.5	698	200.7	23	-	10.23
F-1PZ20	1250	465	93	698	205.35	23	-	5.11
F-1.5PZ20	1250	465	93	698	203	23	-	7.67
F-2PZ20	1250	465	93	698	200.7	23	-	10.23
L-1PZ10	1250	465	46.5	698	205.35	-	23	5.11
L-1.5PZ10	1250	465	46.5	698	203	-	23	7.67
L-2PZ10	1250	465	46.5	698	200.7	-	23	10.23
L-1PZ20	1250	465	93	698	205.35	-	23	5.11
L-1.5PZ20	1250	465	93	698	203	-	23	7.67
L-2PZ20	1250	465	93	698	200.7	-	23	10.23

presents the specifics of the mix proportions. Figure 9 displays the many samples that were cast using the various ingredients listed in Mixtures Table 7.

2.9. Testing

The workability of both LWF and LWL mixes was evaluated using the ASTM C230-97 [41] slump flow table test on fresh mixtures. The water absorption of LWF and LWL measuring 75 × 100 mm after 28 days was assessed in accordance with BS 1881-122 [42]. The samples were left in water for twenty-four hours and then dried in an oven. The density of both types of hardened concrete specimens (100 × 100 × 100 mm) was measured 28 days after curing using ASTM C642-13 [43]. A compression test machine was used to determine the LWF’s and LWL’s compressive strength at 14 and 28 days. Per BS EN 12390 [44]–section 3, the test loading rate was set at 0.1 kN/s. Three 100 mm cube samples of each mixture were analyzed. As stated in BS EN 12390 [44]–section 6, after 14 and 28 days of curing, the splitting strength tensile of the concrete was evaluated. For every concrete mixture, cylinders measuring 100 × 200 mm were cast.

3. Results

3.1. Slump

The fresh mixes that have 10% and 20% zeolite used as a filler instead of cement produce slumping outcomes. Figure 10 illustrates how slump values decreased as PEG-400 was added and the amount of filler cement “increased” from 10% to 20%. To obtain the least amount of slump reduction, several concentrations of zeolite were used. According to Foam Mixes, the decrement ratios in this investigation between the control concrete specimens, “F-CM”, and mixtures comprising 10% zeolite with 1%, 1.5%, and 2% PEG-400 are 3.1%, 6.54%, and 9.62%, respectively. Additionally, in comparison to control concrete specimens “F-CM”, the decrement ratios for mixtures comprising 20% zeolite with 1%, 1.5%, and 2% PEG-400 are 4.36%, 11.92%, and 17.30%, respectively. According to LECA mixes, the decrement ratios in this study between the control concrete specimens, “L-CM”, and mixtures containing 10% zeolite with 1%, 1.5%, and 2% PEG-400 are 3.9%, 8.4%, and 12.3%, respectively. Additionally, as compared to control concrete specimens “L-CM”, the decrement ratios for mixtures comprising 20% zeolite with 1%, 1.5%, and 2% PEG-400 are 7%, 12.6%, and 19.30%, respectively.

Table 8. Results of a test for foamed and LECA concrete.

Mix Id	Target Density	Obtained Density	Slump	Compressive Strength	Water Absorption	Splitting Strength
	(kg/m3)	(kg/m3)	(mm)	(MPa)	(%)	(MPa)
F-CM	1250	1185	260	3.7	29	0.43
L-CM	1250	1234	285	18.6	33	1.96
F-1PZ10	1250	1167	252	4.1	27	0.45
F-1.5PZ10	1250	1142	243	4.37	24.5	0.49
F-2PZ10	1250	1128	235	4.62	21	0.58
F-1PZ20	1250	1150	241	4.3	25	0.49
F-1.5PZ20	1250	1124	229	4.5	23	0.56
F-2PZ20	1250	1110	215	5.1	21.5	0.62
L-1PZ10	1250	1241	274	19.5	29	1.98
L-1.5PZ10	1250	1210	261	20.8	27	2.18
L-2PZ10	1250	1190	250	23	25.4	2.25
L-1PZ20	1250	1175	265	21.7	26.7	2.20
L-1.5PZ20	1250	1171	249	23.1	24.3	2.37
L-2PZ20	1250	1165	230	23.9	21.8	2.41

F “Foam”, L “LECA”, CM “Control Mix”, P “PEG-400”, Z “Zeolite”, 1 “1% of PEG-400”.

illustrates how the foam and LECA particle sizes are irregular than those of normal coarse aggregate, which could account for the decrease in workability. As the additive level of zeolite increases, these particles absorbed a significant amount of water, reducing the fluidity of the LWF and LWL mix [8,21].

3.2. Density

Figure 11 displays the comparison results of hardened density for both LWF and LWL mixtures, and according to target density. It is obvious that incorporating of different ratios of zeolite reduces the density of hardened concrete. According to Figure 11 and Figure 12, the 0% (control sample) with 1250 kg/m³ possessed the highest values for hardened density, especially in case of LWL. However, the F-2PZ20 mixture had the lowest value of hardened density, which was 1110 kg/m³. According to Foam Mixes, the decrement ratios in this investigation between the control concrete specimens, “F-CM”, and mixtures comprising 10% zeolite with 1%, 1.5%, and 2% PEG-400 are 1.5%, 3.6%, and 4.8%, respectively. Additionally, in comparison to control concrete specimens “F-CM”, the decrement ratios for mixtures comprising 20% zeolite with 1%, 1.5%, and 2% PEG-400 are 3%, 5.1%, and 6.3%, respectively. Also, according to LECA mixes, the variation ratios in this study between the control concrete specimens, “L-CM”, and mixtures containing 10% zeolite with 1%, 1.5%, and 2% PEG-400 are increased by 0.6%, decreased by 1.9%, and decreased by 3.6%, respectively. Additionally, as compared to control concrete specimens “L-CM”, the decrement ratios for mixtures comprising 20% zeolite with 1%, 1.5%, and 2% PEG-400 are 4.8%, 5.1%, and 5.6%, respectively. On the other hand, L-CM mix had higher density than F-CM by 4.13%. This is primarily owing to the fact that PEG-400/zeolite mixtures have a lower specific gravity than control mixtures.

3.3. Compressive Strength vs. Splitting Tensile Strength

The concrete mixtures compressive strength and splitting tensile strength containing different quantities of zeolite in place of OPC after 28 days of curing in water is depicted in Figure 13. According to Foam Mixes, the increment ratios in this investigation between the control concrete specimens, “F-CM”, and mixtures comprising 10% zeolite with 1%, 1.5%, and 2% PEG-400 are 10.8%, 18.1%, and 24.9%, respectively. Additionally, in comparison to control concrete specimens “F-CM”, the increment ratios for mixtures comprising 20% zeolite with 1%, 1.5%, and 2% PEG-400 are 16.2%, 21.6%, and 37.8%, respectively. According to LECA mixes, the decrement ratios in this study between the control concrete specimens, “L-CM”, and mixtures containing 10% zeolite with 1%, 1.5%, and 2% PEG-400 are 4.8%, 11.8%, and 23.7%, respectively. Additionally, as compared to control concrete specimens “L-CM”, the decrement ratios for mixtures comprising 20% zeolite with 1%, 1.5%, and 2% PEG-400 are 16.7%, 24.2%, and 28.5%, respectively. The same behavior was observed in the splitting tensile strength with increment values close to the increment values that occurred in the compression test, as shown in Table 8. This may be due to the dilution impact induced by the increased addition of alternative cementitious material to the concrete mix.

3.4. Water Absorption

The pozzolanic reaction and filling impact of zeolite particles within concrete improve the interface. ITZ (transition zone). Furthermore, the reduction in pore capacity in the creation of secondary C-S-H gel provides an explanation for the solid matrix and the impact of finer zeolite particles as a filler. The water absorption value of the samples reduces as the zeolite contents increase, as shown in Figure 14. As zeolite levels rise, the samples’ water absorption value decreases, as seen in Figure 14.

4. Conclusions

The effect of adding zeolite to cement as an additive on the physico-mechanical properties of both LWF and LWL was evaluated in this work. At replacement levels of 10% and 20% of Zeolite, PEG-400 concrete based on Zeolite demonstrated positive effects. The analysis leads to the following conclusions:

▪

PEG-400 can stabilize both of the foam and LECA concrete reducing the surface tension of the water. This stabilization helps maintain uniform air bubbles, which contributes to a more consistent and lower density in the concrete.

▪

By stabilizing the foam, PEG-400 can help increase the total volume of air voids within the concrete. This directly reduces the density of the LWF and LWL.

▪

Adding zeolite as filler reduce the workability of the mix, reducing distribution and of the foam and LECA. This uniform distribution of foam is crucial for achieving a consistent density, so, superplasticizer as” PEG-400” can be used with higher concentration.

▪

Zeolite addition resulted in a decrease in slump values, with PEG-400 having a greater influence on slump reduction than control mixtures. The high surface area and significant amount of water absorbed by waste-containing specimens are the causes of this decrease in workability.

▪

The density of LWF and LWL is decreased by substituting PEG-400/Zeolite for cement in all mixture ratios. As Zeolite are lighter than cement which causes a reduction in LWF and LWL density due to lower cement to zeolite ratio.

▪

The reaction of zeolite in the presence of Ca(OH)₂, which acts as a self-cementing material when it comes into contact with water and forms CSH, is responsible for the strength increase. However, an increase in void content caused by a rise in zeolite contents over the ideal percentage of each one reduced the FC strength.

▪

In place of cement, the concrete’s 28-day compressive and splitting tensile strengths increased with PEG-400/Zeolite increasing. A further increase may indicate to a deterioration in strength.

5. Future Studies

The study of Scanning Electron Microscope (SEM) images of concrete samples containing zeolite is crucial for future research on lightweight concrete that incorporates foam or LECA (Light Expanded Clay Aggregate) for several reasons, Also, SEM studies are essential for gaining a comprehensive understanding of the microstructural and chemical characteristics of lightweight concrete containing zeolite, foam, or LECA. This knowledge is fundamental for advancing the development and application of these innovative materials in the construction industry.