An Investigation into the Local Production Technology of Burnt Bricks in Nigeria

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INTRODUCTION
The locally produced burnt clay bricks in Nigeria feature on the knowledge capacity through acquisition, sharing, and application in transforming raw materials (clay) into finished consumer goods (burnt clay brick). According to studies, the craft involved in the local production of burnt bricks making is a time-proven method that has transcended from generations [1][2]. The burnt clay bricks production technology is almost wholly indigenous and requires simple tools, less scientific skill, and little or no organizational input. The operation is basically for household income generation [1,3]. The mixed production processes, according to studies, varied because of the different customs, civilizations, and availability of raw materials in various regions [3]. Irrespective of production processes and raw material sources, it is expected that the quality of the burnt clay bricks should be consistent with the standards for the proper performance of minima 3.5 N/mm² compressive strength and not more than 20% water absorption. Good clay for bricks production is available in abundant qualities and quantities almost everywhere in Nigeria [2][3]. As no raw material has real value except if it is processed, the combination of resources and application technology to produce goods that satisfy people's needs depend on the ability to do real things expertly [4][5]. Forming and firing the brick are two main stages in the production of bricks. The forming stage is the extraction of the clay, clay preparation, moulding or shaping, and drying. The vital steps in firing the brick are building the field kiln and firing the field kiln. The acceptability of any product is the collection of features such as product performance, reliability, conformance to specification, durability, serviceability, aesthetics, and perceived quality. Technically, all high performance and sustainable buildings superior properties consider certain components of design such as weather resistance, good thermal and acoustic comfort, renewable energy, high compressive strength and durability, water efficiency, excellent fire resistance, safety and security [6][7].
The versatility and durability of brick facilitate its use as part of many sustainable design elements [7]. When the desire properties of these materials are not met, it generates a negative impact, leading to a reduced value and perceived inappropriateness of locally available materials [2]. This necessitates that the controlled properties of burnt clay brick compressive strength, hardness, dimensional stability, thermal expansion, density, abrasion, weight, water absorption, chemical properties, and fire resistance of the finished product be considered at the production process [8][9][10][11]. It is therefore becoming important that the standardized characteristics of bricks in terms of form, size, quality, and strength should be considered [12].
Adapting and complying with the standard characteristic of the burnt clay bricks allow for According to studies preference, and discrimination in using earth-based materials for construction and building projects were observed to cut across the end-users and the builders [10,13]. Some challenges associated with their use include lack of compressive strength, having low resistance to abrasion and highly susceptible to water ingress [14][15]. Beamish and Donovan [12] highlighted form, size and quality as factors contributing to the preference and discrimination of locally made burnt clay bricks. These attributes culminate in making the walls deficient in satisfying new needs in buildings such as roof structures collapse, difficulty in the supply of water and electricity conduits works [16][17]. Maximizing the potential of burnt clay brick in achieving low construction cost, less rural-urban migration, reduced reliance on foreign and imported building materials noted as defects of over-reliance on imported and foreign materials. The quality must be controlled through an effective production process. The knowledge in locally produced burnt clay brick is based on knowledge acquisition, sharing, and application is important to investigate the local production technology of burnt bricks.
Measuring knowledge is discrete facts but measuring skills and the ability to apply knowledge is subjective. As skill can perform a specific task, it can be measured accurately and common and comparable [18][19]. Therefore, this study subjectively evaluated the applied knowledge and skilled on local production technology of burnt bricks and objectively quantified the quality of the burnt clay brick.

MATERIALS AND METHOD
The research approach model in this study methodology is shown in Fig. 1. Subjective measurement of skills and ability in the production of burnt clay brick was conducted among local burnt clay brick producers in Benue State, Nigeria. A Multi-method research approach was adopted in this research process. The multi-method research approach involved subjective evaluation of the skill and knowledge of the burnt brick makers. The skill and knowledge of the burnt bricks were assessed using a questionnaire instrument. The development of the questionnaire was based on the established guideline and standard on burnt clay brick making by Beamish and Donovan [12]. The developed questionnaire was tested for reliability and validated. The quality of the burnt clay brick production practices was quantified through the physical characteristics and mechanical property tests of the produced burnt clay bricks. Sixty local burnt clay brick producers were contacted, and their participations were based on their agreements to supply the relevant information needed for this study. Since there is no official document on the registered local burnt clay brick producers in the study area, the sample size was based on individual contact with the researchers. The local burnt clay brick producers were met at the processes involved in the burnt clay bricks production. Fig. 2 exhibited a selected view for forming stage of the bricks by the participants. This included the extraction of the clay, clay preparation, moulding or shaping, and drying.  Firing stages in the production of bricks which included building the field kiln and firing the field kiln as shown in Fig. 3.  Five burnt clay bricks were randomly picked from the kiln of the 55 burnt clay brick producers making a total of 275 burnt clay bricks. Product quality is a standardized assessment of the superiority of a product was carried out in terms of sizes of the burnt clay brick dimension regarding. The standard dimension used for the comparison was 230x115x73 for length, breadth and height respectively. 275 burnt clay bricks were used for the mechanical property assessment of the bricks produced. These bricks were also measured for compliance with the standard dimension. The values obtained were compared with the standard dimension.
The statistical analyses carried out on the data obtained include descriptive statistics and an independent sample t-test. The descriptive statistics helped in summarizing the data information. The comparative analysis of the established mechanical property produced by the local burnt clay brick producers was through an independent sample t-test. All the analyses were carried out on the SPSS package (20.0). The output significance was ascertained at a confidence level of less than 0.05.

Demographic Characteristics of the Participants
The participants in this study operate in 26 communities within Benue State. All of which were male (100%). Most of the participants had secondary education (45.5%), married (65.5%) and years were of the early adulthood (20-39 years) when male adults' superior physiologically and physical ability performance is at its peak [20][21] need for the strenuous activities of stages of burnt clay brick making.

General Knowledge and Expertise on Burnt Clay Brick Making
The processes at the stages involved in brickmaking are neither technically sophisticated nor complicated. However, the approaches to it might be classified as correct or incorrect as it affects the produced bricks. This is traceable to the producers' knowledge, skill, and experience to produce good quality bricks [12]. The quality of burnt clay bricks is measured by the minimum basic quality standards [22]. The factors affecting the burnt clay brick quality assessed include production technology used, skill set, tools, labour experience, and availability of needed raw materials. Assessing these factors in this study showed that most of the used by most of the participants (91.0%) (Fig. 10). Analysis of the quantity of burnt clay brick production following Beamish and Donovan [12] showed that most of the participants (34.5%) produced 3000-5000 per time.  The clay bricks production unit needs good quality clay to produce a strong brick used in construction. However, not just any type of clay is good for making burnt clay bricks; in a situation like this, analysing the soil, especially in an area where there is no tradition of making bricks. Ibanga and Ahmed [22] added that although the raw materials may be abundant, they may not meet basic standards for proper performance. Eighty percent (80.0%) of the participants that sourced clay materials to produce bricks got the materials from traditional used places and hence, never solicited for the assistance of the local public office for soil assessment and analysis (Figs. 12-15). The various processes and techniques that have led to the burnt brick in this study showed that 58.2% of the study population use the sand moulding method.
Generally, a hard, well burnt, uniform throughout, sound in texture and colour, and sharp shape and dimension is considered a good brick. A dimension of quality of any product (burnt brick clay), according to studies, follows the performance, conformance to requirements, fitness for use, and freedom from defect [23][24][25]. for one week) [12,26]. If the soaked brick does not dissolve or fall apart underwater nor break when dropped, the quality is good enough for construction work. The categories of simple strength tests by the local burnt brick producer in this study are presented in Fig. 15, showing

Measurement of the knowledge and skills on forming and firing stages for standard quality burnt clay brick making
Pointing out knowledge is an alternative to equipment, capital, materials, and labour to become the most important element in production, Drucker [27] predicted that competitive advantage in future is determined by knowledge resources or workers knowledge. Knowledge has an inherent value to be managed, applied, developed, and exploited [28]. Owing to the properties of knowledge, however, knowledge assets require special attention. Knowledge is often embedded in worker has features for product quality which is good for the public [29][30].
Purcell et al. [31] identified that among the basic requirement for optimal performance among workers is requisite knowledge and skills. However, the knowledge must be trendy with development and technology.
Over the years, the art and science of building have taken many reforms in its usability, acceptability, and comfortability [2]. Although the structural design in African has no historical record on the scientific approach to its design and construction, it, however, satisfies thermal comfort, aesthetics, and sustainability reformation conditions [2]. The qualitative and quantitative forms of Nigeria housing question are primarily a crisis in the local production technology for acceptability, cost, durability, aesthetics, and security. The good clay for bricks production available in abundant qualities and quantities almost everywhere in Nigeria [3] serving as raw material for local production of burnt clay bricks are a non-standardized alternative to the factory produced standardized clay bricks [3] if the stages of the production process are handled appropriately. Local production of burnt clay bricks is non-standardized because the production processes and mix productions vary across different producers [3]. The measurement of the knowledge and skills in the forming and firing stages for standard quality burnt clay brick making in this study covers the extraction of the clay, clay preparation, moulding or shaping, drying, building the field kiln and firing the field kiln. Good brick production management is the actual brick for planning, organizing, and controlling the production of the bricks for adequate supplies of raw materials, equipment, and regularly quality checked of the product. This is because the quality of bricks is consistent because of the different production methods employed and the properties of the constituent materials used.
The poor quality and high breakage rate were normally caused by selecting inferior quality clays or/and faulty production techniques during the clay preparation, moulding, drying, and firing stages [12]. The frequency and percentage analysis of the responses to each of the forming and firing stages assessed for each of the participants among the fifty-five (55) local burnt clay brick producers. The investigated burnt clay bricks knowledge and skills for the extraction of the clay and clay preparation, moulding or shaping and drying, building the field kiln, and firing the field kiln stages were calculated for each burnt clay bricks producer that participated in the study. The participants had high knowledge and skill were extraction of the clay and clay preparation (49.1%), average knowledge and skill on moulding or shaping and drying (54.5%), very low knowledge and skill on building the field kiln (41.8%), and low knowledge and skill on firing the field kiln (49.1%) as exhibited in Table 1.

Validation of the burnt clay brick knowledge and skills through experimental analysis (physical characteristics and mechanical property tests)
Product quality is a standardized assessment of the superiority of a product. It is expected that burnt clay brick producers must achieve a quality product that exceeds customers' expectation or call it customer satisfaction. This quality of the product determines the production success or failure. Specifically, the suitability of a material for use on a building is in its properties [32].
The determinant of burnt clay brick product quality produce good quality bricks is the measured regarding the minimum basic quality standards as some knowledge and skills in production processes and practices are about an application [33]. Beamish and Donovan [12]  analysis (physical characteristics and mechanical property tests). The physical characteristic standard measured the brick dimension regarding [34]. The result presented in Table 2 showed that the length (mean ± SD = 229.74 ± 3.99) width (mean ± SD = 114.69 ± 3.87) and height (mean ± SD = 72.48 ± 3.85) had percentage errors of length (mean ± SD = -0.2 ± 1.56) width (mean ± SD = -0.61 ± 3.68) and height (mean ± SD = -0.2 ± 5.73). The dimension of the burnt clay bricks in this study was within the tolerance of approximately 5% for locally produced bricks [12]. The mechanical property tests analyzed for product quality of the burnt clay brick is regarding the minimum compressive strength of bricks of 3.5 N/mm² and the water absorption not exceeding 20%. The independent-sample t-test showed that the mean of the measured water absorption value of the locally produced burnt clay brick was statistically higher (mean ± SD = 29.51 ± 0.58) than the minimum allowable standard water absorption value (mean ± SD = 20.00 ± 0.0) significant at p = 0.00 that is, higher significance as shown in Table 3. A similar observation was made for compressive strength as the measured mean compressive strength value for the locally produced burnt clay brick was 3.98 ± 0.30 N/mm² which was statistically higher than 3.5 N/mm² [35]. The means are significantly different between the mean of measure and standard of the compressive strength was less than 0.05 (see Table 3). The variation in measure and standard values for the water absorption and the compressive strength showed that the locally produced burnt clay bricks were below the acceptable standard value. [36], found out that adequate stacking with proximity to the firing source greatly influences brick properties, the local production process often fails to conform to standard brick production.
What determines whether a material will be suitable for a building is its properties [32].
Compressive strength and water absorption are some of the most important engineering properties desirable for building units, the burnt clay bricks in this study did not meet these basic standards for construction works.

Conclusion
Product quality has been the major tool in achieving reliability and competitive advantage of factors involved in a production process. Assessment of product quality as a yardstick for measuring the product knowledge and skill of local burnt clay brick production for size, quality and strength showed a deficiency in the quality and strength of the produced burnt clay bricks.
The challenge was found knowledge and skills in the forming and firing stages for standard quality burnt clay brick which was only effective in the extraction and preparation stage but deficient in shaping, drying, building the field kiln and firing the field kiln. It is required that for good brick production that will meet the standard brick quality, adequate and updated knowledge is essential for planning, organizing, and controlling the production of the bricks.