25 Records out of 22207 Records

Factors that influence the increase in fire incidences in informal settlements : a case of Mukuru kwa Njenga slum in Nairobi

Author: Limo, Judy Jebet

Awarding University: University of Nairobi, Kenya

Level : MA

Year: 2012

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Mukuru kwa Njenga, Nairobi, Kenya ; Low income groups ; Urban areas ; Fires ; Electric power lines ; Fuels ; Building materials ;

Abstract:

The world has in the past three decades experienced a succession of disasters such as floods, fires, storms, earthquakes, volcanic eruptions and landslides. Fire outbreaks that carry the danger of causing disasters have been a concern both in urban and rural areas. In urban areas fire has been occurring in buildings used for various purposes including residential, commercial, educational, office space, as well as other mixed purposes. Fires are common in Nairobi's slums but urban disasters receive a 'baftling' lack of response from aid agencies, indicating major gaps in urban crisis preparedness (IRIN, 2011). The purpose of the proposed study was to investigate the factors that influence the increase in fire incidences in the informal settlement with a specific focus on Mukuru slum. Specifically the study sought to attain the following objectives: To establish the influence of illegal electricity connections on incidences of fire in Mukuru slum; To establish the influence of increased congestion/population on the incidences of fire in Mukuru slum; To determine how handling of inflammable sources of energy in homes influence incidences of fire in Mukuru slum, and; To establish the influence of construction materials used in homesteads in Mukuru slum on incidences of fire in the slum. This study used descriptive survey design. The target population of this study were the 600,000 adult residents ofMukuru slum occupying 110,000 households (UNDP, 2010). A quota sampling on the households in the area was used to select the study sample. Data was collected from the selected sample using semi-structured questionnaire. The developed questionnaire was administered to the selected subjects in their homes. The questionnaire was hand delivered to the respondents. Collected data was analyzed using descriptive statistics such as percentages, means and proportions. Cross tabulation was also applied as a data analysis technique which measured how the variables in the study were related. Qualitative data from open questions was analyzed using content analysis and presented through narratives. The presentation of fmdings was through tables. Findings indicate that illegal connection of electricity highly influences the increase of fire incidences in Mukuru slum. This is the major contributor to tires in the slums. Congestion has to a great extent increased fire incidences in Mukuru slum. Poor handling of inflammable sources of energy in homes like kerosene and gas have also contributed to the increase of fire incidences in Mukuru slum. However, construction materials used in homesteads in Mukuru slum have only contributed to increase in fire incidences to a small extent. Recommendations made include educating residents on fire hazards and safety through proper handling of inflammable sources of energy. Kenya Power should also carry out a sensitization program on illegal connections of electricity and work together with the government and residents to see how this can be managed. Slum upgrading is another recommendation to replace the poorly designed houses with permanent ones. Finally, fire disaster management infrastructure like fire fighting equipment should be enhanced.

An assessment of the maintenance challenges arising from building design specifications a case study of finishes on commercial buildings in Nairobi, Kenya

Author: Bwonda, J N

Awarding University: University of Nairobi, Kenya

Level : MA

Year: 2011

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Nairobi, Kenya ; Office buildings ; Building materials ; Repair and maintenance ;

Abstract:

This study is about maintenance challenges arising from building design specifications as experienced in commercial buildings in Nairobi. The study assumption is that choice of material and poor knowledge of maintenance as an aspect of building life cycle determines the rate of replacement and therefore maintainability of a building. The literature review has established that various material finishes require a high level of maintenance and even replacement as compared with others. It has also been established that there is a big time lag between the time a maintenance request is placed and the actual work is done. The high cost of initial finish when property specifications are performed lead to less future maintenance cost and better rate of return from a facility.

Factors influencing effective implementation of appropriate building technologies and materials : a case of appropriate building technologies and materials trained community based organizations and individuals in Coast Province

Author: Ng'ang'a, Antony Mwangi

Awarding University: University of Nairobi, Kenya

Level : MA

Year: 2011

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Coast Province ; Appropriate technology ; Building materials ; Soils ; Building construction ; Construction costs ; Construction equipment ;

Abstract:

Appropriate Building Technologies and Materials (ABT &M) refers to building processes, materials and tools that are cost-effective, safe, innovative, green/environmentally friendly as well as acceptable to the climate, socio-economic conditions, and natural resources of an area. It uses soil as its major ingredient. This study aimed at establishing the factors influencing effective implementation of Appropriate Building Technologies and Materials (ABT & M) for reduced cost of construction leading to improved housing situation in Coast province as guided by the following five specific objectives, how training on ABT & M, cost and conception of construction materials, access to equipments and transport cost influences improvement of housing situation The literature review looked at how training on ABT & M helps in dissemination of ABT & M as well as create awareness on the availability of these technologies. It also looked at how access to ABT & M equipments, the cost of construction materials, the conception on the quality of ABT & M building blocks as well as how transport affects the implementation of ABT & M in Coast Province. The research used design was I such a way that, simple random sampling was applied in each of the trained groups (stratum) in counties in Coast province. The sample size was determined by adopting the recommendations ofNkapa (1997) that for a population which runs in to thousands, the sample size should be in the range of 5% to 20%, but for a population that runs in hundreds the sample size should be 50% The size of the target population was 195, and 50% of this population was 98 people. To ensure data validity and reliability, the researcher conducted a pre test of the data collection instrument among the trained individuals of Modem Technology Youth Contractors with the aim of ensuring that, the questions were well understood by all the respondents. Likewise, simple random sampling in each of the trained groups was conducted to ensure that, each respondent had an equal opportunity to be included in the study. The study established that, trainings cost of construction materials as well as the transport factor to a large extent helps in the implementation of ABT & m. The greatest impediment to the effective implementation of the technologies was cited as inadequate access to the ABT & M equipments. This study therefore recommends that, more equipments as well as a wide dissemination strategy for these Technologies is needed. More documentation of the available ABT & M is required so as to disseminate this information to users.

Laterized quarry dust and recycled concrete as alternative building materials

Author: Musembe, Timothy Musiomi

Awarding University: Jomo Kenyatta University of Agriculture and Technology, Kenya

Level : MSc

Year: 2009

Holding Libraries: Jomo Kenyatta University of Agriculture and Technology Library ;

Subject Terms: Building materials ; Concrete ;

Abstract:

The use of conventional materials is facing two main challenges of high cost and large-scale depletion of the sources thus creating environmental problems. These challenges demand that alternative materials be explored that are not only affordable but are also environmentally friendly. In this regard, laterized quarry dust and recycled concrete are proposed as possible alternative building material. To date, extensive studies have been done on laterite, quarry dust and recycled aggregates, separately. However, there is lack of data on performance of blended materials as well as large scale tests on structural elements made from the alternative materials. This research therefore seeks to assess the performance of blended alternative materials when used in concrete and blocks. In the study, samples of materials were investigated to determine basic properties following which the optimum proportions of ingredient materials were determined for concrete and block mix. Finally, the viability of using the materials was assessed for large scale concrete beams and wall panels. The results demonstrate that there is great potential of laterized quarry dust concrete and blocks. When recycled concrete aggregates are used, 300/c, of river sand can be replaced with laterized quarry dust and still attain compressive strength of 20 N/mm2? In addition, the flexural capacities of alternative as well as conventional concrete beams were found to be within 5%. The fmdings are intended to contribute to sustainable construction of low cost housing and development.

Innovating the clay brick firing process : a numerical methods approach

Author: Muchilwa, Isaiah Etemo

Awarding University: Moi University, Kenya

Level : MPhil

Year: 2008

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Bricks USE Building materials ; Building materials ; North Rift, Kenya ;

Abstract:

Brick making in North Rift Kenya continues to consume firewood inefficiently. The current brick firing technology limits the utilisation of alternative fuels and givesbrick makers little control over the process. In general, brick making is largely a 'trial and error' activity and the limited understanding of the process continues to significantly increase the inconsistency in the quantity and quality of the brick yield within the region. Based on the actual material transformations that take place during the firing cycle, this study sought to investigate the technical aspects of the kiln design and operation that had compounded the problem of energy losses and inconsistent brick yields. Numerical analysis software was used to develop a computer-based brick firing kiln simulator with a mathematical model that described the unsteady simultaneous one-dimensional heat and mass transfer during the drying and firing process of clay brick in stagnant bed. Verification of the model was done successfullyon the basis of available experimental data for brick firing. Based on this model the energy saving potential of different process adjustments was investigated and the kiln performance characterised in terms of process specific energy,total fuel consumption, firing time and the brick quality yield. The simulation tests were carried out with maize cobs as the main fuel source, substituting firewood. The simulation results confirmed, as reported in literature, that the brick moisture content and setting pattern, the firing time, temperature, and waste heat recovery were the key energy saving parameters. In quantitative terms the study revealed that the greater potential for reducing the energy requirements for brick firing was in wasteheatrecovery either from recycling the kiln's exhaust gas or in utilising heat obtained from the cooling of fired bricks. The tendency for zoning and the consequentinconsistency in the kilns brick quality yield was found to correspond to high green brick moisture contents, low ai. supply rates coupled with high firing temperaturesduring the drying and preheating phases. The role of exhaust recycling in regulating the firing temperature and thus suppressing zoning has been highlighted. Based on these findings preliminary works were carried out towards developing a new innovative brick-firing kiln fuelled by maize cobs. The realisation of a fully optimised operational kiln that is ready for testing was found to require much more time and resources than was available for the completion of this objective in the present study. Greenbrick weight reduction, involving the use of hollow bricks or through density reduction, by incorporating low bulk density waste organic matter (internal fuels) into the clay mix, was seen as a more direct approach to reducing the energy demand of the firing process. Further research in this area was also proposed.

Screening measurement of indoor radon-222 concentrations by gamma-ray spectromentry in Kenyatta University

Author: Chege, Margaret Wairimu

Awarding University: Kenyatta University, Kenya

Level : MSc

Year: 2007

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Gamma rays ; Radon ; Building materials ; Kenyatta University, Nairobi, Kenya ;

Abstract:

Rn-222 and its progeny are the largest contributors to the total effective dose received by the general public. It is therefore of great concern to monitor radon concentration in dwellings. Measurements of indoor 222Rn concentrations in modern and traditional buildings were carried out for comparison purposes. The measurements were carried out in the Kenyatta University campus in Nairobi, Kenya, where modern buildings and a number of model traditional buildings co-exit. Charcoal canisters were employed to sample 222Rn by exposing the activated canisters at the sampling sites for 48 hours. After exposure, gamma emissions from 222Rn daughters trapped in the canister were analysed using Nal(TI) detector, and the 222Rn concentrations at the sampling sites were calculated. The average 222Rn concentration during the sampling period was 188 Bq/m3. 222Rn concentration varied from 30.2 to 315.4 Bq/m3 in the traditional houses and from 115.76 to 257.2 Bq/m3 in modern buildings. The average 222Rn concentration was higher in the modern building than in the traditional ones. The contribution of building materials as sources of indoor 222Rn was also investigated. This involved gamma spectrometric analysis of samples of building materials to determine their 226Ra concentration, using HPGe detector. The activity concentration of 226Ra ranged from 11.66-101.93 Bq/m3 with the highest value found in the mud used in the construction of the model traditional houses. The ranges of 40K and 232Th in the samples are 254.46-1246.79 Bq/m3 and 15.3 to 148.34 Bq/m3, respectively. The bulk exhalation rates of 222Rn from selected building materials were evaluated by enclosing samples in a 222Rn free can and monitoring 222Rn accumulation with time. 222Rn a exhalation rate was highest in the mud samples and lowest in stone and concrete samples.

Characterization of bituminous mixtures for analytical design of pavements

Author: Kaliti, Julius Mutia

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2007

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Highway construction/Building materials/Quality standards/Materials science ;

Abstract:

Research workers and practitioners in the field of Civil Engineering recognize with disappointment, that both highway and airfield pavements are not analyzed and designed with purely scientific approaches. This state of affairs exists largely because the determination of the stress-strain behaviour and failure criteria, of all the possible modes of failure of pavement materials has not been developed fully. The commonly used pavement materials include bituminous bound, cement bound, unbound aggregates inclusive of cohesionless and cohesive sub grade soils. All these materials must be characterized under the possible in-service loading and environmental conditions, if at all analytical design procedures of pavements are to be developed. The determination of the fundamental properties of materials for analytical design of engineering technical systems is best termed physical characterization. Currently, the commonly used pavement materials evaluation techniques are essentially empirical in nature. These empirical methods of materials evaluation are collectively referred to as technological characterization. As such there is insufficient understanding of the fundamental behaviour response of pavement construction materials, under varied traffic loading and environmental conditions. This suggests that the current conventional pavement design procedures and materials specifications do not take into account the actual materials fundamental behaviour response to all in-service loading conditions. As such it is not possible to estimate the various resistances or strengths of different pavement materials and pavement structural elements to varied load effects. Hence, it becomes increasingly difficult to obtain design criteria against the possible modes of materials failure, and therefore pavement functional and structural failures. Therefore, it cannot be overemphasized that there is a necessity to continuously replace the conventional design procedures, which are largely technological or empirical in nature, with design procedures based at least partly, if not wholly, on the fundamental properties of pavement materials. Consequently economical and durable technical systems can be designed from the local materials under the prevailing climatic conditions. Generally, it is recognized that technological methods of materials and pavement design are very well entrenched in the practice of pavement engineering. However, if conversion from technological to physical pavement materials characteristics is possible by means of constitutive laws, then it would mean that technologically designed materials can be characterized in either way, i.e. technologically or fundamentally, and then converted to the other. Such an approach would be appropriate in handling the physical characterization of pavement materials whose current design procedures are largely technological. This indicates the need to develop constitutive

Assessment of stabilised soil blocks technology as a low cost housing material : a study of Eldoret Municipality

Author: Keter, Julius K

Awarding University: Moi University, Kenya

Level : MPhil

Year: 2007

Holding Libraries: Moi University Margaret Thatcher Library ;

Subject Terms: Housing/Building materials/Soils/Eldoret, Kenya/ ;

Abstract:

Effective Housing materials ought to be, durable, strong and affordable in order to be used in the production of quality-housing units to majority of the poor. One of the materials that meet these criteria is stabilised soil blocks (SSBs). SSB has received attention recently as a suitable building material for low cost housing in several parts of Kenya. However, little research has been undertaken within Eldoret Municipality concerning the use of SSBs as a low cost walling material. A 3-month study investigating suitability of soils, compressive strength and cost effectiveness of SSBs as building materials was thus undertaken in Eldoret municipality. Soil samples were obtained from 5 zones, Kimumu, Langas, King'ong'o, Munyaka and Rehema estates. Suitability of soils for SSBs was based on Pedological classification, granulation test, (sieve and sedimentation analysis) and atterbergs limit tests. Compressive strength of SSBs was tested using Dennison hydraulic press machine while cost effectiveness of SSBs as building material was compared to other conventional materials based on a prototype low cost house. Results indicated that laterites of fine to medium texture are dominant. They are found in large proportions in depths ranging from 1-3 feet below the ground level. The particles size distribution of laterites in the research area is 32% fine -coarse sand, 52% fine- medium gravels and 16% silt and clay. The soils have liquid limit of (60.2), plastic limit of (39.6) and plasticity index of (20.6). The compressive strength of SSBs increased linearly with increase in cement ratio while the specific gravity of SSBs was higher than those of unstabilised blocks. The most cost effective ratio that yielded structurally sound blocks was 6% cement and 2% lime. In conclusion, soils in Eldoret are suitable for SSBs production and are highly recommended for SSBs production.

Characteristics and suitability of using Kenyas natural pozzolana rocks and burnt agro-residues as a substitute to ordinary portland cement clinker.

Author: Singoei, Kemboi Benjamin

Awarding University: University of Nairobi, Kenya

Level : MSc

Year: 2006

Holding Libraries: University of Nairobi Jomo Kenyatta Memorial Library ;

Subject Terms: Geology/Cement/Building materials/Cement industry/ ;

Abstract:

The pozzolana materials considered in this research work were of two categories namely; natural and artificial. The natural pozzolana rocks were classified at the Department of Geology, t (UON) as Trachytic tuff (TT), lithic tuff (L T), light brown grey tuff (LBGT) and light grey tuff (LGT). The chemical compositions were characterized mainly using the wavelength dispersive xray spectrometer (WDXRF) equipment of the type rigaku geigerflex, which is a sequential automatic x-ray spectrometer modeled by Siemens srs-l. Other instruments used were the flame photometer for analysis of alkali metals and the gravimetric methods for sulphate. The results showed silica oxide as the dominant compound, i.e., TT, 64.68%; L T, 66.15%; LBGT, 63.20%; and LGT, 63.21%. Alumina was the second major component in the chemical composition with 13.56%, 12.78%, 18.99%, and 14.89% in TT, LT, LBGT and LGT, respectively. The agro-based pozzolana was obtained from Rice husk ash (RHA) and Sugar-Cane Bagasse ash (SCBA). They were incinerated at temperatures between 500 and 600?C to obtain a reactive silica, hence the name artificial pozzolans. Their chemical compositions were similarly determined using the Wavelength Dispersive X-Ray Spectrometer (WDXRF) instrument; Silica oxide was also noted to be the dominant compound in RHA (76.23%) and SCBA (65.46%). Compressibility and Microchemical analysis of the pozzolana materials were determined using a 2000 N compressive machine and EDX instrument, respectively. Compressibility data were a result of cement mortar formulation of pozzolana material with a known proportion of OPC-clinker. Formulations considered for each pozzolan materials were 15%,20%,25% and 30%. The formulation of 30% result showed RHA' s 2-days compressive strength of 11.45 N/mm2. The control set had a compressive strength of20.26 Nzrnm, which was 76.94% higher than the mortar strength ofRHA. The 2 days minimum standard strength requirement is 10 N/mm2. Twenty eight (28) days curing showed compressive strength value of 46.98 Nzmm, which was 3.75% higher than the control set. Thirty percent (30%) formulation of SCBA showed 28 day's compressive strength of 30.05 N/mm2. The results were 33.56% lower than the 45.22 N/mm2 compressive strength of the control set. X-ray powder diffractometer (XRPD) results indicated RHA to be mainly in amorphous state confirming the non-crystalline material. The results obtained compared well with the high strength development obtained in the cement mix. A 50:50 pozzolana -filler ratio formulation of25% (i.e. 12.5% LGT+ 12.5% Filler) and 30 % (i.e. 15% LGT+15% filler) indicated 97.96% and 91.27% compressive strengths, respectively, compared to the 28 days standard strength requirement of 32.5N/mm2 . The reactivity of a pozzolana material may not be established on the basis of total silica content, but on the reactive the silica. Microchemical analysis showed RHA to contain the amorphous silica, SCBA was mainly crystalline with minor traces of sanidine. Both TT and LGT contained sanidine, LBGT showed Analcime and Merlioite as the major phases whereas L T showed amorphous silica with traces of Calcite, quartz and Bayerite. All the pozzolans considered showed high combined silica content (A h03+Si02) above 70%, therefore meeting Kenya's requirement of a pozzolana material. The RHA had 77.24 % silica, whereas LT had 78.93% silica. Paste physical appearance showed OPC, TT and LGT to be light grey, whereas RHA and SCBA were dark grey and LBGT was light brown grey. The use of an agricultural residue as a substitute to clinker in ordinary portland cement (OPC) requires large plantations of the crop plant. Therefore, RHA cement having strength enhancing properties requires joint efforts from the rice farmers and the cereal boards, for the production of sufficient ash material for use in cement. In addition,clinker reactivity needs a further study on the various types of pozzolana materials.

Pozzolanicity of selected kaolinites with special focus on pyroprocessing parameters

Author: Gathua, Joseph Kimiri

Awarding University: Kenyatta University, Kenya

Level : PhD

Year: 2005

Holding Libraries: Kenyatta University Moi Library ;

Subject Terms: Clay ; Minerals ; Masonry ; Building materials ; Kaolinite ;

Abstract:

In this study, the pozzolanic reactivity of selected clay minerals (kaolin) with lime was investigated mainly to establish their suitability in low cost housing. Clay minerals from eleven different regions in Kenya were characterized using x-ray diffraction, x-ray fluorescence and the differential thermal analysis coupled with thermogravimetry. The X-ray diffraction tracings for all the samples showed features of disorder that made the exact quantification of the clay minerals difficult, but estimates showed that kaolinite ranged between 30-74%. The results also showed that the clay minerals were mixed- layered or interstratified. The results of chemical analysis showed predominance of Si02 and A1203 with Fe203 being the next major constituent. All the samples met the Standards IS-1344-1981 on chemical composition of pozzolanas. The thermal behaviour was monitored using differential thermal analysis coupled with thermogravimetry. Adsorbed water was released in the range 50-90?C. The dehydroxylation reaction occurred in the range 525-600?C and was accompanied by phase transformation from the crystalline kaolinite to the amorphous or quasi- amorphous metakaolin phase. Another change of phase in some samples was observed in the range 900-980?C, which signified recrystallization (fusion) of the collapsed structure into spinel. Three samples with the highest content of kaolinite namely, Mwingi Kaolin (sample A-2), Kisii kaolin (sample A-3) and Nyeri kaolin (sample G) were selected for pozzolanic reactivity tests with lime alongside kaolin Caminau, Kaolin Guttau and diatomaceous earth. Kaolin Caminau and Guttau were sourced as packaged industrial products from Freiberg, Federal Republic of Germany, while diatomaceous earth was sourced as an industrial product from the African Diatomite Company, Gilgil- KenyaThe optimum activation temperature and thermal activation time were established by thermally activating the samples at varied temperatures and time using soak method in a muffle furnace. The two parameters were then determined on the basis of compressive strength of the pozzolanallime mortars cured for 7 days and dissolution method. The latter method entailed dissolution of thermally activated pozzolana in dilute hydrofluoric acid and subsequent measurement of electrical conductivity. The optimum activation temperature and thermal activation time ranged between 650-800?C and 3-4 hours respectively. The results showed that dissolution can be an effective and quick method of establishing the pyroprocessing parameters. The optimum pozzooanal Lime ratio for the six pozzolanas was in the range 2.3-3.0 and the results were in agreement with pozzolanic investigations done elsewhere.. Kaolin Caminau and diatomaceous earth registered high compressive strengths during the first 7 days of curing and limited strength development thereafter indicating a very fast rate of hydration. Kisii, Mwingi and Nyeri kaolin recorded very low strength during the first 7 days but the strength developed progressively upon curing up to 28 days signifying slow rate of hydration. The pozzolanicity of soak calcined Kisii kaolin using the Thattle model of vertical shaft kiln (VSK) was compared with that of electric muffle furnace (EMF). The results indicated that kaolin calcined in EMF was more reactive with lime than the V SK calcined one. Investigations were extended to comparison of the soak and flash calcinations methods. The flash method produced more reactive metakaolin than the soak method. Thermal decomposition under isothermal conditions was also implicitly monitored on the basis of electrical conductivity measurements. The results indicated that this method is a good indicator of the structural changes taking place within a pozzolana upon thermal activation. All the samples attained compressive strength of 4MP after 28 days of curing as per the IS-1344-1981 standards, an indication that they can be used as pozzolanas for ordinary masonry purpose.