Experimental study of strength and durability properties of fly ash-lime-quarry dust (FALGQ) bricks

ABSTRACT

The paper deals with the results of an experimental investigation related to the properties of fly ash-lime-gypsum-quarry dust (FALGQ) bricks and their masonry. The strength, absorbing capacity, and efflorescence of FALGQ were examined. In addition, concrete՚s strength, the cement mortar and fly ash brickwork՚s stress-strain properties, and the flexure՚s resistance to cracking were also studied. The results show that: (1) FALGQ can be produced with a greater density using a fly ash-sand combination than with fly ash alone; (2) it is feasible to achieve 12 to 14 MPa strength development in a wet condition, a relatively low value of absorption of water, strong dimensional stability and strength properties for FALGQ using 35% lime, 10% quarry dust, and 30% gypsum; and (3) high rupture elasticity and deformation significantly impact in fly ash brick masonry. This study also contrasts the durability of bricks with that of burned clay bricks, specifically examining weight reduction and the decrease in strength qualities resulting from an acid test.

Keywords:
Absorption; Durability; Fly ash gypsum; Quarry dust; Strength

1. INTRODUCTION

The disposal of industrial waste exacerbates environmental problems and has an impact on natural resources. The disposal of industrial waste on these sites will have an impact on the ecosystem and may result in contamination. We utilise and recycle industrial waste to create bricks as a solution to these issues. The constructed infrastructure all around the world has been profoundly influenced by the green concept in terms of design and development. Delivering “high-performance building systems” is becoming increasingly popular.

One that meets the requirements outlined in the Energy Policy Act of 2005 [¹] is referred to as a “high-performance building.” Fly ash masonry has been studied for its strength properties, and it has been discovered that due to its low moisture absorption, high compressive power [²], strong flexural strength properties, and fracture toughness, it remains to behave significantly from clay masonry. Buildings and masonry components typically experience tensile failure while under compression stress. This happens as a result of the brick’s tensile modulus being higher than its strength properties. When a material achieves its mature condition, the initial amount of water collected has no impact on compression strength, as shown by the connection between initial absorptivity and compressive strength [¹]. The quantity of wall force that passes perpendicular to and parallel to the route of the bed joint greatly affects the brick masonry’s resistance to destruction [³].

In comparison to regular clay bricks that produced good results, fly ash bricks have a lower absorption coefficient and higher compressive strength. They also weigh less and have more porosity. Fly ash brickwork can be utilized in place of clay bricks, according to the findings of the inquiry [⁴]. A wall’s tensile or strength qualities are diminished by bond degeneration, and they may even be completely eliminated. By leaking via a weak link, water can cause damage. Mechanical properties have an impact on structural behaviour as well. Due to the bond contact between the mortar and the masonry, for instance, masonry is strong in compression but weak in flexural tension [⁵]. Similar to those found in block masonry, there were possibilities for failure. Customers that interact with physical stores experience loss. But when brick and bonding are connected, failure happens, as in the cases of rich cement mortar (type A) and combination mortars D and E.

Regardless of the masonry design, the flexural bond strength usually increases in tandem with the mortar qualities of cement mortar [⁶]. This set of samples had a higher beginning water absorption rate than the others, though. This demonstrates that when it reaches its mature form, the compressive strength was unaffected by the initial water absorption rate [⁷]. This feature is described by the IRA, as the suction effect created by water penetration by capillary action in the bricks, which suctions water from the mortar. The absorption rate may have a considerable impact on how freshly applied mortar interfaces with the brick blocks. IRA is measured during the construction phase to assist with mortar choosing and material handling. The amount of water utilized is used to calculates as the previous study [⁸].

The stress-strain profiles for every one of the four portions of brick were produced by averaging the data from 10 species of each type of brick. It was observed that the bricks’ behaviour was linear until it reached roughly one-third of the final breaking strain, when it significantly changed. An average stress-strain graph is displayed for each variety of brick used in the research [⁹]. Values for acid weight loss somewhat increased as firing temperature increases after 1125 °C. This is most likely brought on by a rise in open pores, which coexist with trends in water absorption rates that are increasing. Furthermore, the slight increase in acid weight loss (0.06–0.53 percent) is presumably the result of the same mineralogical stages that develop at all firing temperatures for different combination compositions and do not produce any novel stages to enhance acid weight loss [²].

Based on the literature, it was found that there has been minimal research on the behaviour of masonry constructed using these pebbles, as well as on the physical attributes of fly ash brickwork and boulders. Consequently, the primary objectives of the present study are to evaluate the structural features of fly ash brickwork and the aspects of fly ash brick masonry.

2. MATERIALS AND METHODS

Examining the characteristics of FALGQ bricks and their masonry is the main objective of this investigation. A minimum of 20–30% of lime by weight of fly ash–sand mixture becomes essential to produce fly ash lime bricks of satisfactory strengths. Gypsum should be present at an ideal level of 25% to produce fly ash compacts with a compressive strength of 35%. Fly ash content between 20% and 40% in cementitious binder displays decreased water uptake and increased structural qualities for use in the construction sector [¹⁰]. Optimum proportion arrive on the FALGQ brick (fly ash 35%, lime 10%, gypsum 25% and quarry dust 30%).Thoroughly Mix the fly ash, lime and gypsum in dry condition with ball mill and quarry dust shall be added to the same. After adding the required quantity of water and this thoroughly mixed sample. This mixture poured into the brick making machine and applied compression load is applied. The bricks are raised using hydraulic machine and the same is shifted to storage location. After drying for one day proper curing (Sprinkling) for 7 days. Therefore, the concluded combination for further studies is fly ash 35%, lime 10%, Gypsum 25% and Quarry dust 30%. Based on the combination arrived, the mechanical properties of compressive strength, water absorption, density (wet to dry), efflorescence and shrinkage etc., are studied. Further studies on the behaviour and strength parameter were done based on the tests performed and the characteristics evaluated for the fly ash bricks and their masonry are as follows:

• (a)

  Characteristics of fly ash bricks

  1. Wet and dry compressive strength

  2. Water absorption and Initial Rate of Absorption (IRA)

  3. Linear expansion on saturation

  4. Weight loss after durability test

  5. Stress-Strain relation of fly ash brick

  6. Durability of brick

     1. Acid test

     2. Sulphate test

  7. Modulus of rupture test (flexural strength of brick)

  8. Erosion Test of Brick

  9. Shrinkage Test of Brick

  10. Split Tensile strength of Brick

• (b)

  Characteristics of fly ash brick masonry

  1. Compressive strength of mortar

  2. Flexure bond strength of masonry

For the following reasons, the FALGQ ratio was used. The compressed lime-fly ash specimens’ porosity (a) has the biggest impact on durability. For lime-fly ash bricks, a dry density of more than 15 kN/m³ cannot be surpassed when fly ash is the only ingredient. Maximum dry density can be achieved by mixing fly ash with sand [¹¹]. (b) Using high lime-fly ash proportions produces products with the highest strength. Sand is added to the mixture, which enables the decrease of fly ash while maintaining an extremely high lime-fly ash ratio. Stronger construction is achieved by having a high density and a high fly ash-gypsum-lime ratio [¹¹]. In order to achieve the best result, a mixture of ingredients was used. In the previous study, the combination of the mixture described was fly ash 35%, Lime 10 per cent, Gypsum 25 per cent, and Quarry dust 30%. The distribution curves of grain size are shown in Figure 1.

Figure 1
Grain size distribution.

According to the result, the regularity coefficients Cu (D60/D10) and the coefficients of curvature CC (D302/(D10 × D60)) are 2.71 and 6.23, respectively. The homogeneity coefficient is defined as the ratio of D60 to D10 (Cu). If the soil’s Cu value is between 4 and 6, it is regarded as having a good grade. A soil’s unevenness or poor grading is determined by its Cu value, which must be at least 4. The particle distribution suggests that the soil is appropriately graded because the Cu value of evenly graded soil is close to 1, and both the CC and Cu values are within the range of well-graded soil.

2.1. Characteristics of fly ash bricks and Gypsam

The dry and wet compressive strengths were originally created. Moreover, the water permeability and initial rate of absorption were computed. The test was run, and the measurements were made with a 96-day-old subject. It has been shown that as these bricks age, their strength grows. It is found that the amount of improvement in compressive strength, although gradual, is greater in the first 14 days.

2.1.1. Linear expansion on saturation

On saturation, linear expansion on an extensometer, the linear expansions on saturated fly ash bricks were calculated. Figure 2 depicts the experimental setup and the length comparison. The following is the test process that was used.

Figure 2
Liner expansion on saturation.

• (a)

  A digital vernier calliper was used to evaluate the oven-dried brick’s length.

• (b)

  The brick’s top surface was secured with a metal point. The initial volume of the digital dial gauge (least count 0.000 mm) was obtained after positioning the dry brick beneath it.

• (c)

  After that, the block was let to soak for 24 hours in potable water at room temperature. After 24 hours, the soaked specimen was removed and put into the length comparator equipment with the metal point that was fastened to the brick’s surface facing the dial gauge tip. It was noted what the equipment dial gauge remains unaltered for the length of the investigation.

• (d)

  The brick’s linear growth is determined by the disparity between the initial and final dial gauge measurements. This can be converted into a % of the lengths in the dry region, from which it is possible to determine the linear extensions on saturation pressure.

2.1.2. Weight loss after durability test

The durability of fly ash bricks was examined by conducting cyclic wetting and drying and wire scratch test as per the procedure given in ASTM D559 code [¹²]. The setup is presented in Figure 3. One cycle of wetting and drying is represented by the processes. The method was repeated for a further 12 cycles, this time immersing the specimens in water. At the end of each cycle when performing studies and carrying out specific studies, weight measurements of the specimen before and after brushing (wire brush) are typically made. Calculate the specimens’ oven-dry weight by weighing the samples after 12 test cycles of drying them to a consistent weight at 230°F (110°C). The information gathered will enable estimations of specimen volume and water content changes as well as brick losses. Compressive strength loss after the required 12 test cycles were established for both results, and were compared with rural burnt clay brick.

Figure 3
Weight loss after the durability test.

2.1.3. Stress-strain relationships for the fly ash bricks

The fly ash blocks’ stress-strain coefficients were determined using displacement-regulated testing techniques. Figure 4 depicts the test configuration for identifying stress-strain connections and a strain gauge that gauges the force by tracking the vertical motion of the brick over time. Relationships between stress and strain were discovered in a saturated condition. The bricks were evaluated 48 hours after already being submerged in water to look for relationships between stress and strain in a moist climate. It is indicated that the presence of moisture (or a saturated state) is essential for any structure to function. The ultimate braking load was also noted, and the same results are compared with Country burnt clay brick.

Figure 4
Stress-strain relationship set-up.

2.1.4. Tests for WA and IRA of bricks

The WA test determines the brick’s overall water absorption capability. Bricks’ concentration gradient draws moisture from the atmosphere into the bricks, sucking mortar’s water in with a suction effect. For the purpose of EN 772-11, IRA describes this characteristic. The rate of absorption may have a considerable impact on how freshly applied mortar interacts with the brick units. IRA is monitored during the construction process to assist with mortar choosing and material handling. The bricks were evaluated 48 hours after being submerged in water to look for relationships between tension and stress in a moist climate. During the test, water was added to maintain a constant water depth. Figure 5 displays the difference in IRA between Fly ash bricks and country-burned clay bricks. The amount of water absorbed was found to range from 0.3 to 0.9 per cent. The FALGQ brick absorbs water at a rate between 16.5 and 21%.

Figure 5
IRA of FALGQ and country burnt clay brick.

2.1.5. Durability test

(a) Acid resistant test

With a precision of 1 g, the mass of the specimens in SSD was calculated using an electronic weighing balance. Measurements were made of the sample’s strength properties before and after the acid test was performed. The pH readings of the acid bath were taken weekly. The acid bath was replaced by a new one if the pH had changed noticeably. The outcomes of weight loss and compression strength gains were then calculated. Different samples are created by altering the raw material composition, and each specimen must undergo characteristic tests like compression and flexural tests as well as tests for water and acid mass loss and absorption. Figure 6 depicts the acid test.

Figure 6
Acid test.

The FALGQ and nation burned specimens were placed in a water bath for 4 days after being air-cured to saturate the specimens. To produce saturated surface condition (SSD) and avoid sorption before the acid resistance test, all samples were scrubbed with a moist towel. The starting mass was then determined. Following that, the strength of the concrete of 3 samples of each type of material was determined. To avoid cross-contamination, three separate integrates multiple nine specimens of each kind were placed, separately, into the prepared 5%, 3%, and 1% sulfuric acid baths during the test. After washing the specimen with tap water and blotting it dry with a moist towel, the mass and compression strengths of 3 samples of each kind were assessed on the 7th, 14th, and 28th day under SSD conditions. In this study, we found that the bricks and tiles manufactured performed well in HCL and H₂SO₄ media in compliance with IS:4860-1968 [¹³].

(b) Sulphate test

The first step was to make the sulphate solution by mixing water with 5% sodium sulphate and 5% magnesium sulphate by weight. The setup is shown in Figure 7. For a total of 28 days, the specimen was submerged in the sulphate solution. By frequently switching the solution, the concentration of the mixture was preserved during this time. The sample was removed from the sulphate solution after 7, 14, and 28 days, depending on the time period, and the brick’s surface was cleaned, weighed, and evaluated for compressive strength.

Figure 7
Sulphate test.

Bricks soaked in 1%, 3%, and 5% sulphate solutions had compression strengths that ranged from 7.84 to 6.48 MPa, whereas blocks that had undergone natural curing had compressive strengths that ranged from 9.4 to 13.60 MPa. Usually, the corrosion rate was 21%. Due to the development of a useful method for strengthening the hardened mix’s resistance to sulphate attacks using fly ash and quarry dust as pozzolanic components, the bricks produced in this study had greater strength attributes.

(c) Erosion test

To ascertain the specimen’s rates of erodibility, an erosion experiment utilizing the Drip (Geelong) method was carried out (see Figure 8). New Zealand Standard was followed in conducting the test (NZS 4298, 1998). Figure 9’s configuration of the apparatus included a water container with a 100 ml indication from the top. A 16 mm wide strip of Wettex (J-Cloth) was applied to the container in order to absorb and transfer the water onto the sample. This test must be carried out in a location shielded from wind and direct sunshine in order to drop the water precisely [¹⁴].

Figure 8
Geelong erosion test details.

Figure 9
Erosion test of FALGQ and county burnt clay brick.

The test sample must be made as shown in the Figure 9 and allowed to cure for at least 28 days before being tested. The samples were positioned 400 mm vertically distant from the J-Cloth and at a 27° angle at the base. Water (100 ml) was dripped onto the J-Cloth every 20 to 60 minutes. After that, the specimen was measured for pit depth in order to determine how deep the pit was produced. A cylindrical probe with an end diameter of 3.15 mm was used to penetrate the test surfaces and determine the depth of the pit. The current findings demonstrate that there were no surface depressions on either the FALGQ specimens or the rural burnt clay brick. These findings imply that they would be completely erosion-resistant and able to tolerate exposure to extreme weather events [¹⁵]. Further, the speed of soil block erosion is influenced by block densification. The low-interest rate of compaction decreased the erodibility rate while enhancing the density of the soil blocks. This implies that the impact of erosion by rain or water on the pieces is lessened and lowered the compaction ratio of creating soil blocks [¹⁶]. Therefore, FALGQ brick has no erosive characteristic when compared to country-burned brick. The outcome thus demonstrates that the material is more erodible and compatible than country-burned brick.

(d) Shrinkage test

When used for serial dilutions of rammed earth, the sample Open top shrinking boxes must be capable of withstanding ramming pressure whether they are made of steel or wood. Each shrinkage box is 600 mm long, 50 mm wide, and 50 mm high on the inside. To stop moisture absorption from the sample, wooden boxes must be coated or oiled. The box must have smooth, square ends. If required, metal shims can be used to create a smooth end surface for measuring against. To prevent the material from clinging to the device, the cavity’s sides and bottom must be lined with 2 layers of newsprint. Either a single box or several boxes can be assembled side by side. Figure 10 depicts the shrinkage test.

Figure 10
Shrinkage test.

Pick up a sample of the suggested mix that has been made in the same way that it will be used during construction. Make a sampling of the mix with the same amount of material and water contents as would typically be used to build a wall in order to test rammed FALGQ for shrinkage. A suitable hand or machine rammer should be used to ram it forcefully into the shrinkage box. Keep the specimen moist for 7 days while covering it with plastic, then let it air dry for a further 21 days away from the sun. Create a mix at the optimum moisture % for the intended application in order to evaluate a sample of poured FALGQ mix. Then, without leaving any gaps or holes, insert the specimen into the shrinking box. Cure ramming combines samples properly. For tested samples lime, moist cure as described above for 21 days, followed by 7 days of air drying. Before measuring, the specimen is made sure to be dry. After at least 28 days, it is much simpler to detect cracks, gauge mould shrinking, and quantify it with mechanical feeler gauges the smoother the sample’s surface. Push the sample firmly from each end if it has cracks running the length of it. Add the results after measuring the shrinkage at both ends. Shrinkage measured shrinkage (mm) = (measured shrinkage (mm)/600 mm) × 100 [¹⁴].

2.1.6. Split tensile strength test of brick

The evaluation was completed following ASTM C1006 [¹⁶] (American Society for Testing and Materials, 2013). The FALGQ and country burnt clay brick’s bed surface experienced a line load during this test. The masonry units developed tensile tension as a result of the compressive applied pressure to the bearing rods. A bearing rod with a 10-millimetre dimension maintained the bed’s centre, and a second bearing rod was situated transversal to the first opposite bed surface, as shown in Figure 11a, b. When the experiment broke, the rate of tensile stress breaking was between 100 and 200 psi/min [0.7 and 1.4 MPa/min], and the load capacity was steady and consistently applied to the bearing rod without shock [¹⁶]. The weight was kept on the brick until it broke in order to document the maximum load. The ultimate failure load is noted and included in the calculation below to determine the split tensile strength of both bricks.

Figure 11
(a) Split tensile strength of FALGQ brick. (b) Split tensile strength of country burnt clay brick.

The split tensile strength of the ICEB was determined using the equation

(1) $$Ft=\frac{2P}{P}HL$$

where Ft = splitting tensile strength, P = maximum load, L = split length, and H = distance between rods.

Numerous experiments were carried out to establish the tensile stress of FALGQ and part of the world bricks (Figure 12).

Figure 12
FALGQ and country burnt clay brick.

2.1.7. Modulus of rupture of brick

The impact modulus also referred to as the ruptured elasticity, of a molecule, is the flexural force that a substance can endure before giving way. Using upper and lower rollers to impart a lateral deformation, the flexural modulus of a prismatic sample is determined, on other hand the modules of rupture were calculated with the accuracy of 0.01 Mpa by using the following equation

(2) $$S=\frac{3W\left(1/(2-x)\right)}{b{d}^2}$$

where S = modulus of rupture of the sample at the plane of failure, lb/in.2 (Pa); W = maximum load suggested by the testing apparatus, lbf (N); l = distance between the supports, in (mm); b = net width, (face to face minus voids), of the sample at the plane of failings, in (mm); d = depth, (bed surface to bed surface), of the sample at the plane of failings, in (mm). Find the mean of the ruptured modulus estimations to within 1 psi and characterize it (0.01 MPa). Chemistry and cement content has an impact on strength properties, which are also known as bend power, transverse rupture strength, or fracture modulus. The flexural, compressive, and diametrical tensile strengths of nanocomposites are higher, as are their elastic moduli.

2.1.8. Compressive strength of mortar

The fly ash brick masonry prisms employed in the current investigation were cast using cement lime mortar in a ratio of 1:5 (cement and sand, by volume). The method outlined in BS 4551 [¹⁷] was used to figure out the flow value of the mortar. The brick prisms were cast using mortar that had a flow value of 76% according to ASTM C 1437 [¹⁸] which translates to a water-cement ratio of 1.65. Fresh mortar utilized in the masonry project was transformed into mortar cubes (50 mm dimension). Cement mortar was used to cast the fly ash masonry wall prisms used in the current study in a 1:5 ratio (cement to sand, by volume). After being cured for 28 days in water, these cubes were tested for hardness, and an average of three cubes produced 19.9 MPa. Compressive strength of mortar is shown in Figure 13.

Figure 13
Compressive strength of mortar.

2.1.9. Flexure bond strength of masonry

By applying tensile stresses that “wrenches” the topmost bricks away from the majority of the compositions, the bond wrenches testing can evaluate the flexural strength properties of multiple mortar joints in a single masonry prism. Application of pressure to a mortar joint with the aid of cantilevered arm results in compression in one section of the joint and tension in the other. This test was conducted in line with EN 1052-5. The masonry was submerged in water before the masonry prisms were cast. Figure 14 illustrates the variety of flexure bond strength values for the FALGQ and region-burnt clay bricks with cement mortar 1:5.

Figure 14
Flexure bond strength of FALGQ and country bunt brick.

The flexure bond length of FALGQ prisms is greater than that of prisms formed of clay bricks that have been burned in a field. Fly ash brick construction has superior tensile properties due to the bond that develops between the mortar and FALGQ brick on the brickwork surface. Nevertheless, our investigations showed that when the bond strengths and ultimate strength of the mortars were both larger than that of the bricks, brick strengths commonly turned into clustering in masonry buildings. It was necessary for this particular circumstance to achieve the desired flexural strength properties [¹⁹]. This goes further than a commonly used procedure of bond creation between hardened concrete and also the mortars, which involves mechanically bonding hydration reaction constituents into brick permeable. Figure 14 shows the numerous failure patterns that could be observed in the prisms used for flexure bond testing. These disasters can be divided into three groups, which are detailed below. Brick-mortar interface failures, (a) Type A, occurs in the complete separation of the mortar bed joints from the brick. (b) Type B: bricks and mortars that have partially failed will both flex at the failure plane when they come into contact with each other. The failing brick portion will be adherent to the mortar bed joint at the interaction to a 20–40% extent. (c) Type C: whole brick failure–the brick-mortar connection is finished, but the failures take place via the brick that is nearest to the contact. When the interface’s flexure bond strength exceeds the flexure strength of fly ash brick, this occurs.

3. RESULT AND DISCUSSION

As the experimentation setups and procedures explained above, all the experiments were performed and the results are obtained and noted. The results of the above-mentioned experiments are explained graphically and the measurements are tabulated in this section.

3.1. Characteristics of fly ash bricks

3.1.1. Wet density, dry density, water absorption and compressive strength

Initially, the wet test, dry test, water absorption and compressive strength were performed and the results are presented in Figures 15,16,17 and Table 1. (a) Type A: interface failure–in this type of failure, the mortar bed joint at the brick-mortar interaction will completely separate from the brick. (b) Type B: partial brick/mortar breakdown–the failure surface at the brick-mortar interface will exhibit flexure failure of the brick as well as the mortar joint. 20 to 40 per cent of the defective brick piece will adhere to the mortar bed joint at the interface. (c) Type C: whole brick collapse–brick-mortar interface is intact. However, the failure occurs through a brick near the interface. This happens when the flexure strength of fly ash blocks is lower than the networking adapter’s strength properties. Wet-to-dry density is almost the same in all ages. But water absorption will increase as the number of days increases but it will be constant from day 56 onwards.

Figure 15
Wet and dry density.

Figure 16
Water absorption.

Figure 17
Compressive strength development.

Table 1
Grade definition and strength of FALGQ brick.

GRADE	TEST NAME	DAYS
		7th	14th	28th	56th	96th
M11	Wet density	1719	1747.7	1797	1781.8	1802
	Dry density	1629	1547	1564	1529	1544
	Water absorption	5.7	13	14.9	16.5	16.7
	Compressive strength	3.7	8.9	9.8	12	13.6

3.1.2. Linear expansion on saturation

A test that is standardised for determining the dimensional accuracy of soil blocks that have been compressed and consolidated is called linear expansion on saturated [²⁰]. The laboratory tests have shown that stabilized soil blocks with linear expansion on saturation <0.1% led to satisfactory wall performance against moist environmental conditions. The fly ash brickwork examined in this study exhibit linear expansion on saturation (mean of 6 samples) between FALGQ brick and Country burnt clay brick, which is between 0.015 and 0.039%. This means that the fly ash bricks have very good dimensional stability upon saturation.

3.1.3. Weight loss after durability test

Monitoring the weight loss in the bricks after 12 cycles of artificial weathering test as defined in ASTM D559 is performed. Based on the previous study, it was attempted to correlate the results of the artificial weathering test with the field observations for stabilized soil block constructions [²¹]. The research concluded that the weight loss after such a weathering test limited to <3% results in good quality stabilized soil blocks. Based on our results it was concluded that the weight loss after such a weathering test was limited to <3%. The FALGQ brick tested in the present investigations shows a weight loss in the range of 2.1–2.91% and Country burnt clay brick ranges to 1.89–3.1%. These values indicate that the fly ash bricks are expected to show good performance when exposed to adverse weathering conditions. Figure 18 depicts the condition of the fly ash brickwork (FALGQ and Country burnt bricks) before and following 12 cycles of moist and dry testing. Even after 12 repetitions of the extreme weathering testing, the bricks rarely show any signs of wear.

Figure 18
Stress-Strain graph of country burnt clay brick an FALGQ bricks.

3.1.4. Stress-strain relationships for the fly ash bricks

The stress strain relationship between the both the brick samples were presented in Figure 18. The initial tangent modulus of fly ash bricks is in the range of 8000–8446 MPa. With an improvement in fly ash brick toughness, the modulus rises. The study provided the burnt clay brick modulus values having compressive strength 30–34.5 MPa. According to the findings, fly ash bricks have a 90–95% greater modulus than locally burned clay bricks.

3.1.5. Tests for WA and IRA of bricks

Thus, according to EN 772-11 [²²], the initial level of absorption was estimated. An important factor in achieving this goal is the early rates of absorption in brick masonry walls. The masonry units in the wall must have a strong bond with the masonry mortar. The bond’s performance is significantly impacted by brick absorption, notably the Initial Rate of Absorption (IRA).

This is consistent with the determined initial absorbing rate (IRA) in 1, where the mean IRA of FALGQ and Country Burnt clay brick is 0.3 and 0.9 kg/(m²/min), a high premium (clay brick IRA’s typically range between 0.35 and 3.60 kg/(m²/min)) clearly indicates that the Country burnt clay bricks absorb water more rapidly than FALGQ brick. The brick walls originally absorb water rapidly (the absorption rate is greatest during the first 1 min of immersion). Results show that the IRA and water absorption are less when compared to country-burnt clay brick as per 3495 and ASTM C67.

3.1.6. Durability test

The relative importance of the studies that have emerged from the acid test conducted is displayed in Table 2. The weight loss of FALGQ bricks for 28th day in acid bath with 1%, 3% and 5% of acid were 0.8%, 2% and 2.4% respectively. The weight loss of Country burnt bricks for 28th day in acid bath with 1%, 3% and 5% of acid were less than 1%. There was no major weight loss, which may be due to the bonding strength.

Table 2
Acid and sulphate test.

SOLUTIONS NAME	%	BRICK NAME	COMPRESSIVE STRENGTH (MPa)	WEIGHT LOSS (%)
Sulphate test (28th day)	5	FALGQ	6.3	1.1
	3		7.8	0.6
	1		11.8	0.1
	5	Country burnt clay	4.8	1.6
	3		5.1	1.3
	1		5.8	1.2
Acid test (28th day)	5	FALGQ	5.1	2.4
	3		7.7	2
	1		8.54	0.8
	5	Country burnt clay	4.35	0.9
	3		4.35	0.8
	1		5.8	0.5

The strength loss of FALGQ bricks for 28th day in acid bath with 1%, 3% and 5% acid were 29%, 36% and 58% respectively. As the percentage of acid increased, the strength loss increased. Surface blistering was also seen. The strength loss of FALGQ for 28th day in acid bath with 1%, 3% and 5% acid were 8%, 31% and 31% respectively.

The effect of sulphate attack was evaluated by measuring the compressive strength and weight losses of the specimen at 28th day and the process continued with FALGQ brick compared with the Country burnt clay brick. The weight loss of FALGQ bricks for 28th day in Sulphate with 1%, 3% and 5% acid were 0.1%, 0.6% and 1.1% respectively. The weight loss of Country burnt bricks for 28th day in acid bath with 1%, 3% and 5% acid were 1.2%, 1.3% and 1.6% respectively. The weight loss was negligible, which may be due to bonding strength.

The strength loss of FALGQ bricks for 28th day in acid bath with 1%, 3% and 5% Sulphate were 2%, 35% and 48% respectively. The strength loss of FALGQ for 28th day in Sulphate with 1%, 3% and 5% acid were 8%, 19% and 24% respectively.

Compressive strength loss may be due to internal cracks developed when acid and sulphate attack expand. So far, there are no reports on the occurrence of internal cracks. Hence further elaborate studies are required to investigate on this aspect.

3.1.7. Erosion test

When compared to county-burnt clay brick no erosion was seen in the FALGQ brick, but a 2 mm depression is seen in the country-burnt clay brick. So, it was indicated that FALGQ brick is of no erosion. The property of erosion is shown in Table 3. It may due to combination of fly ash and cement with gypsum makes a strong between the quarry dust particles rather than conventional clay bricks.

Table 3
Erosion property.

AVG DEPTH OF PIT IN mm	ERODIBILITY INDEX	RATING
FALGQ	0	Non-erosive
Country burnt clay	2	Slight erosive

3.1.8. Shrinkage test

On verifying the result, it was understood that no shrinkage cracks are seen in the moulded material. So, the material is more stable and resistant to the shrinkage crack and that indicates the bonding between the particles and materials.

3.1.9. Split tensile strength test of brick

Overall, FALGQ bricks can be employed as masonry in a building. Country burnt clay brick split compressive modulus is greater than FALGQ brick for both cases. Results of experimental research into the split tensile strength of FALGQ brick and country-burnt clay brick are presented. The split tensile strength of building structures is a crucial factor in determining the maximum load that could cause the constructions to split. FALGQ and country-burnt clay bricks were put through split tensile testing. The outcomes are shown for the evaluation of the consequence. The maximum split tensile strength of the FALGQ brick lengthwise in a dry environment is 1.19 N/mm², and it achieved the highest of 0.44 N/mm². Table 4 displays the outcomes of each condition’s examination. An investigation by [²³] found that the split tensile strength of ICEB components can be impacted by both the design and manufacturing processes. The study also discloses that the tensile modulus of hollow blocks is 10% of its impact strength, which is changed from 0.96 N/mm² at 28 days. All of the aforementioned situations were fulfilled in a dry environment. However, FALGQ bricks also failed due to a tensile crack that travels along the axis of the loading, unlike country-burnt clay, which did not fulfil the requirement of the identical extent. This is because tests with rods focused longitudinally on bed faces typically have higher coefficients of variation than tests with rods focused transversely. Figure 19 shows graph for Split tensile strength.

Table 4
Characteristics of fly ash bricks.

DETAIL OF THE PROPERTY	UNITS	FALGQ	COUNTRY BURNT CLAY BRICK
Wet compressive strength	MPa	15.01	7.4
Dry compressive strength	MPa	12	6.3
Wet-to-dry compressive strength ratio	%	0.8	0.85
Initial rate of absorption (IRA)	g/cm2/Min	0.3	0.9
Water absorption	%	16.5	21
Linear expansion on saturation	mm	0.015	0.024
Weight loss after durability test (wet to dry)	%	1.4–1.5	0.9–.07
Wet density		1781.8	1798
Dry density		1528	1485
Wet to dry density ratio		0.86	0.82

Figure 19
Split tensile strength.

3.1.10. Modulus of rupture of brick

Table 4 provides the findings of the various tests performed on fly ash bricks. Tests were performed to evaluate compressive strength (wet and dry), water absorption, linear expansion on saturation, IRA and durability. Table 5 provides information on the average scores, standard deviation, and dry density of test samples for fly ash bricks in comparison to country-burned clay bricks. The greatest bending stress that may be given to a material before it yields is known as the material’s flexural strength or modulus of rupture. By imparting a bending moment to a prismatic sample using upper and lower rollers, the flexural strength of the sample is determined. According to testing results, FALGQ brick’s flexural strength significantly outperformed country-burned clay brick in both wet and dry conditions, as well as length and width-wise. Measurements for the modulus of rupture which ranged from 1.18 MPa to 1.3 MPa in FALGQ’s wet-to-dry condition, are shown in Table 5. Impact strength and rupture elasticity are depicted as having a linear association in Figures 20 and 21. This correlation might be influenced by the kind of natural resources employed, the pattern’s structure, and the shaping method [²⁴]. Therefore, it was anticipated that the modulus of rupture would react similarly to compressive strength. It is proven that the strength was observed from dry to wet conditions due to the modulus of rupture. A similar approach was discovered in earlier experiments on the billet scale [²⁵]. According to ASTM C67-07a, 2003 [²⁶], the lowest allowable limit of modulus rupture for brickwork is 0.65 MPa. Clay bricks tested for modulus of rupture under dry and wet environments yielded results between 0.07 and 0.89 MPa. In conclusion, the brickwork created in this data suggested excellent outcomes for the fracture modulus when compared to typical burnt clay bricks.

Table 5
Modulus, erosion, shrinkage property.

DETAIL OF THE PROPERTY	CONDITION	FALGQ	COUNTRY BURNT CLAY BRICK
Modulus of rupture test	Wet	1.18	0.7
	Dry	1.3	0.89
Erosion test of brick (mm)	Wet	Nil	1 mm
Shrinkage test of brick	Wet	Nil	–

Figure 20
Modulus of rupture test.

Figure 21
Compressive strength of cement mortar.

4. CHARACTERISTICS OF FLY ASH BRICK MASONRY

4.1. Compressive strength of mortar

The compressive strength of the mortar cube is in the range from 7^th to 28^th day 13.3 to 19.6 Mpa which was lower than brick strength, so it is more safer in structural in fill application especially in seismic zone.

4.2. Flexure bond strength of masonry

The results of these bonding wrench tests are listed in Table 6. According to conventional masonry and FALGQ, failure in strain (flexure) and shearing should occur in the weaker construction joints rather than the stronger concrete components.

Table 6
Flexural bond strength of FALGQ and country burnt clay brick.

THE COMPRESSIVE STRENGTH OF CEMENT MORTAR IN 1:5 PROPORTION IS 9 Mpa
Details of property	FALGQ	Burnt clay brick
Brick strength ultimate (MPA)	34.5	15.2
Initial tangent modulus	8445.9	370
Peak at strain	0.00132	0.00956
First crack (MPA)	10	15
Flexure bond strength (MPa)	1.5	0.7
Failure type	Type-A, B	Type-C

Table 6 shows the flexural bond strength of both bricks. The establishment of the bonding between the brick and indeed the mortar is influenced by a wide range of factors. The mechanical interlocking of hydration products from cement into the brickwork pores at the mortar-brick interface is the primary cause of bond formation. The bond strength of the masonry prisms is significantly influenced by the moisture content of the brick at the time of casting for bricks that are only slightly soaked, the strongest connection is achieved. So, in the current experiment, before casting the masonry reflectors, stones were partly wet by soaking them in water. SARANGAPANI et al., [²⁷] showed flexure strength properties readings in the range of 0.088–0.12 MPa for brickwork employing local burnt clay bricks and comparable cement lime mortar. Flexure bond tensile strengths for the FALGQ and county burnt clay brick with cement paste 1:5 are in the range of 1.5 and 0.7 MPa. The flexure bond stress of FALGQ brick prisms is more than that of Country burnt clay brick prisms. The bond formed between cement and brick (in the mortar) and unreacted FALGQ on the brick surface is what gives FALGQ brick masonry its stronger bond. Figure 22 shows Stress-strain curve of FALGQ and country burnt clay brick.

Figure 22
Stress-strain curve of FALGQ and country burnt clay brick.

4.2.1. Stress-strain relationship for fly ash bricks and mortar

• a)

  Table 6 gives the type of bond failure for the FALGQ brick masonry prisms. The majority of the prisms show Type A and Type B modes of failure, except country-burnt clay which was showing Type C failure. Country burnt brick prism has the lowest compressive strength and when compared to FALGQ brick, it was 15.2 Mpa only, which was seen in the report with 56% variation for individual results.

• b)

  The initial tangent modulus of fly ash bricks is in the range of 8445.9 MPa. When compared to country-burnt clay brick 95% higher modulus was seen in the report. Gypsum addition has led to an increase in strength as well as the modulus for fly ash bricks. SARANGAPANI et al. [²⁷] report modulus values of burnt clay bricks (having compressive strength 4.6–8.4 MPa) in the range of 3200–5200 MPa. FALGQ bricks show 38–62% higher modulus when compared to FALGQ bricks.

• c)

  The strain at peak stress is in the range of (FALGQ and country burnt clay brick) 0.00132 and 0.00956. The corresponding strain value for local burnt clay bricks is about 0.001 [²⁷]. FALGQ bricks show higher straining capacity when compared to burnt clay bricks.

• d)

  First, the knowledge of stress-strain characteristics is essential for the analysis and design of masonry. It is essential to understand the deformation characteristics of new materials like FALGQ bricks. The stress-strain relationships, modulus and strain values indicate that FALGQ bricks and their masonry show higher modulus and energy absorption capacity when compared to country-burnt clay bricks of comparable strength.

5. SUMMARY AND CONCLUSION

The characteristics and result comparison of compressed FALGQ bricks and their masonry, mortar cubes etc were discussed.

The wet strength to dry strength ratio is about 0.8 and having wet strength of 15.01 MPA at 96^th day also has reasonably low values of water absorption as per the ASTM/IS codal provision, and high density of 1781 kN/m³. It was observed that when compared to the previous studies, the Fly Ash-Lime-Gypsum combination absorbed more water, but the combination of fly ash-lime-Gypsum-quarry dust mixture reduced the water absorption and proved the same with the IRA result. The FALGQ brick, which had a lower water absorption rate and improved strength properties, showed better strength reduction property when put through acid and sulphate testing. It also showed no signs of erosion or shrinkage cracking. The results of the test for split tensile strength and the modulus of rupture were satisfactory, and good split tensile strength and modulus rupture were also recorded. Flexural bond strength for FALGQ masonry using cement mortar is high when compared with burnt clay brick, no breakage was seen on the brick. It was proved that the brick has good stability and compressibility with a 1:5 proportion of mortar masonry.

In this study, an empirical analysis of the traits of fly ash-lime-gypsum-quarry dust (FALGQ) brickwork and their construction was carried out. The strength, absorbency, and longevity of FALGQ were investigated. Using four different kinds of fly ash bricks and concrete mix, the strength properties, flexure bond strength, and stress-strain parameters of fly ash brick masonry were studied. According to the findings, it is possible to manufacture FALGQ with an increased concentration using a fly ash-sand combination rather than fly ash alone and fly ash brick masonry exhibits higher tensile and flexural bond strength, modulus of rupture, opposing erosion, and shrivelling features when compared to fly ash alone. Additionally, the findings demonstrated that it is feasible to produce FALGQ with a higher density using a fly ash-sand mixture rather than fly ash on its own.

6. ACKNOWLEDGMENTS

Thanks for Noorul Islam university providing lab facilities to this research.

7. BIBLIOGRAPHY

• ^[1]
  ALI, N., DIN, N., KHALID, F.S., et al, “Compressive strength and initial water absorption rate for cement brick containing high-density polyethylene (HDPE) as a substitutional material for sand”, IOP Conference Series. Materials Science and Engineering, v. 271, n. 1, pp. 012083, 2017. doi: http://doi.org/10.1088/1757-899X/271/1/012083.
  » https://doi.org/10.1088/1757-899X/271/1/012083
• ^[2]
  EL-MAHLLAWY, M.S., “Characteristics of acid resisting bricks made from quarry residues and waste steel slag”, Construction & Building Materials, v. 22, n. 8, pp. 1887–1896, 2008. doi: http://doi.org/10.1016/j.conbuildmat.2007.04.007.
  » https://doi.org/10.1016/j.conbuildmat.2007.04.007
• ^[3]
  REDDY, B.V.V., “Long-term strength and durability of stabilized mud blocks”, In: Proceedings of the 3rd International Conference on Non-conventional Materials and Technologies, pp. 422–431, Hanoi, Vietnam, 12-13 March 2002.
• ^[4]
  VARMA, P.G.D.M., GADLING, P., “Comparative study on fly ash bricks and normal clay bricks”, International Journal for Scientific Research and Development, v. 4, n. 9, pp. 673–676, 2022.
• ^[5]
  SARHOSIS, V., GARRITY, S.W., SHENG, Y., “Influence of brick-mortar interface on the mechanical behaviour of low bond strength masonry brickwork lintels”, Engineering Structures, v. 88, pp. 1–11, 2015. doi: http://doi.org/10.1016/j.engstruct.2014.12.014.
  » https://doi.org/10.1016/j.engstruct.2014.12.014
• ^[6]
  WEN, B., ZHANG, L., NIU, D., et al, “Mechanical performance of confined autoclaved fly-ash-brick Masonry walls under cyclic loading”, Applied Sciences, v. 11, n. 22, pp. 10560, 2021. doi: http://doi.org/10.3390/app112210560.
  » https://doi.org/10.3390/app112210560
• ^[7]
  ALI, N., DIN, N., KHALID, F.S., et al, “Compressive strength and initial water absorption rate for cement brick containing high-density polyethylene (HDPE) as a substitutional material for sand”, Materials Science and Engineering, v. 271, n. 1, pp. 012083, Nov. 2017.
• ^[8]
  VENU MADHAVA RAO, K., VENKATARAMA REDDY, B.V., JAGADISH, K.S., “Flexural bond strength of masonry using various blocks and mortars”, Materials and Structures, v. 29, n. 2, pp. 119–124, 1996. doi: http://doi.org/10.1007/BF02486202.
  » https://doi.org/10.1007/BF02486202
• ^[9]
  ALEX, A.G., JOSE, P.A., SABERIAN, M., et al, “Green pervious concrete containing diatomaceous earth as supplementary cementitous materials for pavement applications”, Materials, v. 16, n. 1, pp. 48, 2022. doi: http://doi.org/10.3390/ma16010048. PubMed PMID: 36614394.
  » https://doi.org/10.3390/ma16010048
• ^[10]
  ALEX, A.G., BASKAR, R., “Behaviour of micro & nano particles in M-sand cement mortar”, International Journal of Applied Engineering Research, v. 11, n. 1, pp. 385–391, 2016.
• ^[11]
  VENKATARAMA REDDY, B.V., GUPTA, A., “A Tensile bond strength of soil-cement block masonry couplets using cement-soil mortars”, Journal of Materials in Civil Engineering, v. 18, n. 1, pp. 36–45, 2006. doi: http://doi.org/10.1061/(ASCE)0899-1561(2006)18:1(36).
  » https://doi.org/10.1061/(ASCE)0899-1561(2006)18:1(36)
• ^[12]
  ALEX, A.G., KEMAL, Z., GEBREHIWET, T., et al, “Effect of α: phase nano Al₂O₃ and rice husk ash in cement mortar”, Advances in Civil Engineering, v. 2022, pp. 4335736, 2022. doi: http://doi.org/10.1155/2022/4335736.
  » https://doi.org/10.1155/2022/4335736
• ^[13]
  BIIATIA, S.M., Specification for acid-resistant bricks, Calcutta, Institution of Engineers, 1969.
• ^[14]
  NEW ZEALAND STANDARDS, NZS 4298 Materials and workmanship for earth buildings, Wellington, NZS, 1998.
• ^[15]
  OBONYO, E., EXELBIRT, J., BASKARAN, M., “Durability of compressed earth bricks: assessing erosion resistance using the modified spray testing”, Sustainability, v. 2, n. 12, pp. 3639–3649, 2010. doi: http://doi.org/10.3390/su2123639.
  » https://doi.org/10.3390/su2123639
• ^[16]
  AMERICAN SOCIETY FOR TESTING AND MATERIALS, ASTM C496/C496M-11 Standard test method for splitting tensile strength of cylindrical concrete specimens, West Conshohocken, ASTM, 2011.
• ^[17]
  BRITISH STANDARDS INSTITUTION, BS 4551 Mortar-methods of test for mortar and screed-chemical analysis and physical testing, London, 2005.
• ^[18]
  CABINETS, M., ROOMS, M., “Standard test method for flow of hydraulic cement mortar 1”, In: American Society for Testing and Materials (ed), Annual book of ASTM standards, West Conshohocken, ASTM, 2012.
• ^[19]
  LAWRENCE, M., HEATH, A., WALKER, P., “Development of a novel binder for mortar for unfired clay bricks”, In: Proceedings of the 2nd International Conference on Sustainable Construction Materials and Technologies, pp. 28–30, Ancona, Italy, June 2010.
• ^[20]
  VENU MADHAVA RAO, K., VENKATARAMA REDDY, B.V., JAGADISH, K.S., “Flexural bond strength of masonry using various blocks and mortars”, Materials and Structures, v. 29, n. 2, pp. 119–124, 1996. doi: http://doi.org/10.1007/BF02486202.
  » https://doi.org/10.1007/BF02486202
• ^[21]
  VENKATARAMA REDDY, B.V., “Long-term strength and durability of stabilised mud blocks”, In: Proceedings of the 3rd International Conference on Non-Conventional Materials and Technologies, 2002.
• ^[22]
  PRIMMER, P., “The use of EN771‐4 the European harmonized AAC masonry unit product standard in the UK”, ce/papers, v. 2, n. 4, pp. 565–570, 2018. doi: http://doi.org/10.1002/cepa.884.
  » https://doi.org/10.1002/cepa.884
• ^[23]
  BARBOSA, C.D.S., HANAI, J.B., “Strength and deformability of hollow concrete blocks: correlation of block and cylindrical sample test results”, Revista IBRACON de Estruturas e Materiais, v. 2, n. 1, pp. 85–99, 2009. doi: http://doi.org/10.1590/S1983-41952009000100005.
  » https://doi.org/10.1590/S1983-41952009000100005
• ^[24]
  KAVAS, T., “Use of boron waste as a fluxing agent in production of red mud brick”, Building and Environment, v. 41, n. 12, pp. 1779–1783, 2006. doi: http://doi.org/10.1016/j.buildenv.2005.07.019.
  » https://doi.org/10.1016/j.buildenv.2005.07.019
• ^[25]
  AL-OTAIBI, S., “Recycling steel mill scale as fine aggregate in cement mortars”, European Journal of Scientific Research, v. 24, n. 3, pp. 332–338, 2008.
• ^[26]
  AMERICAN SOCIETY FOR TESTING AND MATERIALS, ASTMC 67-03 Standard test method for sampling and testing bricks and structural clay tile, West Conshohocken, ASTM, 2003.
• ^[27]
  SARANGAPANI, G., VENKATARAMA REDDY, B.V., JAGADISH, K.S., “Brick-mortar bond and masonry compressive strength”, Journal of Materials in Civil Engineering, v. 17, n. 2, pp. 229–237, 2005. doi: http://doi.org/10.1061/(ASCE)0899-1561(2005)17:2(229).
  » https://doi.org/10.1061/(ASCE)0899-1561(2005)17:2(229)

Publication Dates

• Publication in this collection
  09 Sept 2024
• Date of issue
  2024

History

• Received
  09 Mar 2024
• Accepted
  20 May 2024