Papers by Babatunde J Olawuyi
(CSSA), member of both fib and RILEM and currently serves in the RILEM TC 260-RCS. His research i... more (CSSA), member of both fib and RILEM and currently serves in the RILEM TC 260-RCS. His research interests cover cementitious materials, concrete, fibre reinforced concrete and sustainable development. ABSTRACT Superabsorbent polymer (SAP) addition as an internal curing (IC) agent in high-performance concrete (HPC) has been adjudged to be effective in mitigating autogenous shrinkage. The influence of SAP created voids fresh properties and early strength development of the HPC as cement hydrates is however yet to be well understood. This paper hereby presents a report of an experimental study on SAP incorporation as an internal curing agent in a low water/binder (W/B) HPC. Four reference HPC mixtures (M1F, M1S, M2 and M3) designed for a 28-day minimum cube compressive strength of 70 N/mm 2 (MPa) were examined for the effect of SAP grain size, content and binder type on setting times and degree of hydration. The study also involved the determination of the pH-value of the simulated cement pore solution obtained from the binder combination types and its influence on SAP absorbency in concrete. It was observed that the addition of SAP resulted to increase in the setting times, while the degree of hydration of the HPC mixtures was found to increase as SAP content increases. The higher the SAP grain size, content and W/B for all mixtures, the higher the chemically bound water () at specific times and this increased as the hydration period increases. INTRODUCTION The incorporation of superabsorbent polymers (SAP) in concrete is gaining acceptance as an internal curing (IC) agent especially in high-performance and ultra-high performance concrete. However, the effect of its utilisation on cement hydration and strength development in these types of concrete is yet to be fully understood. Amongst the issues of concern is the effect of SAP on the fresh properties of concrete such as workability, setting times and rate of hydration. Also, the influence of the cement pore solution (CPS) concentration on the rate of fluid absorption and
Portland cement (PC) been the world most commonly used binder in mortar/concrete applications is ... more Portland cement (PC) been the world most commonly used binder in mortar/concrete applications is adjudged a non-environmental-friendly material due to its green house (carbon dioxide – CO 2) gas emission mainly during production. Previous studies on the search for alternative binders had centred on utilisation of natural Pozzolan or ashes from agricultural wastes (agro-wastes) as partial replacement of PC in mortar or concrete construction while reports on total replacement are scarce in literature. Incinerated ashes from agro-wastes at controlled temperature have been found to be pozzolanic with major components been amorphous silica which combines with lime in the presence of water to give cementitious properties. This paper report on exploratory study on agro-waste ashes (RHA and SHA – silica sources) in combination with industrial waste materials (calcium carbide waste (CCW) – a CaO source) as alternative binder for total PC replacement in mortar/concrete construction. Pastes from the different combination ratio of RHA/CCW and SHA/CCW were studied for setting times, degree of hydration and strength development. The study revealed the RHA and SHA samples to be of high SiO 2 (93% and 84%) while CCW is majorly CaO (66% content). The agro-dustrial binders (RHA/CCW and SHA/CCW) showed good binding properties at a slow hydration rate. Mortar samples from 60/40 RHA/CCW and 70/30 SHA/CCW gave best performance having 28day compressive strength of 5.3 N/mm 2 [MPa] and 7.5 N/mm 2 [MPa] representing 25% and 35% of CEM I strength.
Incorporating Superabsorbents Polymers (SAP) as internal curing agents (IC-agents) in high perfor... more Incorporating Superabsorbents Polymers (SAP) as internal curing agents (IC-agents) in high performance concrete (HPC) for mitigation of autogenous shrinkage is one new trend in concrete practice. SAP's water absorption and desorption as cement hydrates however leaves micro voids within the concrete which can negatively influence the mechanical properties of HPC. The SAP content, sizes, binder composition, solid constituents of concrete and curing age could be of direct influence on the resultant air voids sizes and its distribution in concrete. This paper therefore reports on three dimensional (3D) volume analysis of the influence of SAP contents and curing age on air voids distribution in HPC. Four HPC mixtures with different binder constituents and water/binder (W/B): M 1F and M 1S (0.2), M 2 (0.25) and M 3 (0.3) were tested with two grain sizes of SAP (SP 1 6 300 lm and SP 2 6 600 lm). The SAP contents were also varied (0%; 0.2%; 0.3%; and 0.4%) by weight of binder. Concrete cylinders (50 mm b  100 mm) were cast and cured in water for different ages (7, 28, 56 and 90 days) before the hardened HPC was subjected to X-ray computed tomography (CT) scanning for determination of the air void distribution. The analysed 3D X-ray images gave results on SAP grain sizes, SAP air voids, distribution and volume in the HPC with the respective influence of binder type, W/B and curing age assessed.
This study investigates the influence of curing age and mix proportions on the compressive streng... more This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA) blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm 2 (using British Method) was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT) contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm 2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α 0.5) on the compressive strength of the VA-blended cement laterized concrete.
The use of Superabsorbent Polymers (SAP) is one internal curing method being adopted for mitigati... more The use of Superabsorbent Polymers (SAP) is one internal curing method being adopted for mitigation of autogenous shrinkage in concrete especially high strength / performance concrete (HSC/HPC). SAP absorbs water and release the water internally when concrete hydrates. It however leaves micro voids in this process; this can negatively influence the mechanical properties of concrete. This paper therefore reports on three dimensional (3D) volume analyses of the air voids in HPC containing SAP as internal curing agent. Three HPC mixtures with different water/binder (w/b) ratios (M1 (0.2); M2 (0.25) and M3 (0.3)) were tested with two grain sizes of SAP (˂ 300 µm with product label FLOSET CS 27 and ˂ 600 µm, labelled FLOSET CC 27). The SAP contents were also varied (0%; 0.2%; 0.3%; and 0.4% by weight of binder). Concrete cylinders with 50 mm in diameter and 100mm in height were cast and cured in water for 28 days before the dry hardened HPC was subjected to X-ray computed tomography (CT) scanning for determination of the air void distribution. The 3D X-ray images were then examined and analysed using Avizo Fire image analysis software -version 8.0 to filter and classify the individual voids for determination of the sizes, distribution and volume analysis of void created by SAP in the HPC with the respective influence of binder type and water/binder ratio assessed. The CT scanning was also used to affirm the grain sizes of the dry SAP and their absorption in pore solutions.
X-ray computed tomography is a well-known technique to measure porosity in materials such as conc... more X-ray computed tomography is a well-known technique to measure porosity in materials such as concrete, though this usually involves time consuming scans and complex analysis procedures. Many of these involve custom software or programming procedures. In this paper, a simplified procedure is presented and demonstrated using results obtained from basic procedures with commercial software packages, with minimal image processing. The same sample was subjected to scans ranging from 100 μm to 5 μm resolutions, demonstrating the multiscale ability of commercial CT scanners. Scans done at typical high-quality conditions (1 hr duration) in comparison to very fast scans (5 minutes) are also presented and it is demonstrated that useful information is still obtained from such lower quality faster scans. This demonstrates the concept that X-ray CT is simple and cost effective for research and industrial applications, not requiring expert 3D image analysis experience, for obtaining good porosity information.
RILEM Proceedings (PRO 95) by RILEM Publications S.A.R.L., Sep 14, 2014
The use of Superabsorbent Polymers (SAP) is one internal curing method being adopted for mitigati... more The use of Superabsorbent Polymers (SAP) is one internal curing method being adopted for mitigation of autogenous shrinkage in concrete especially high strength / performance concrete (HSC/HPC). SAP absorbs water and release the water internally when concrete hydrates. It however leaves micro voids in this process; this can negatively influence the mechanical properties of concrete. This paper therefore reports on three dimensional (3D) volume analyses of the air voids in HPC containing SAP as internal curing agent. Three HPC mixtures with different water/binder (w/b) ratios (M1 (0.2); M2 (0.25) and M3 (0.3)) were tested with two grain sizes of SAP (˂ 300 µm with product label FLOSET CS 27 and ˂ 600 µm, labelled FLOSET CC 27). The SAP contents were also varied (0%; 0.2%; 0.3%; and 0.4% by weight of binder). Concrete cylinders with 50 mm in diameter and 100mm in height were cast and cured in water for 28 days before the dry hardened HPC was subjected to X-ray computed tomography (CT) scanning for determination of the air void distribution. The 3D X-ray images were then examined and analysed using Avizo Fire image analysis software – version 8.0 to filter and classify the individual voids for determination of the sizes, distribution and volume analysis of void created by SAP in the HPC with the respective influence of binder type and water/binder ratio assessed. The CT scanning was also used to affirm the grain sizes of the dry SAP and their absorption in pore solutions.
Research and Applications in Structural Engineering, Mechanics and Computation – Zingoni (Ed.) © 2013 Taylor & Francis Group, London, ISBN 978-1-138-00061-2, Sep 2, 2013
This paper reports the absorption capacity of super-absorbent-polymer (SAP) in water and cement p... more This paper reports the absorption capacity of super-absorbent-polymer (SAP) in water and cement pore solution. This was considered for the free water requirement for high-performance concrete containing SAP. The rheology and compressive strength properties of this low water/binder (w/b) concrete are reported. A 2 × 5 × 4 × 3 factorial experimental arrangement was used for the study. Two sizes of SAP (03/08 µm and 06/12 µm) monomers acrylic acid were tested at different SAP contents (0%; 0.2%; 0,3%; 0.4%; and 0.6% by weight of cement) for concrete mix proportion of 0.25 w/b ratio (F cu28 ≥ 80 MPa target strength).Specimens were also tested at different curing ages namely 3, 7, 21 and 28 days. The results are presented in this paper with a discussion on the influence of water absorbed by SAP at the mixing stage on the compressive strength of the high-performance concrete.
Internationa Conferece on Advances in Cement and Concrete Technology in Africa (ACCTA 2013), Jan 28, 2013
gate on the compressive strength and elastic modulus of high performance concrete (HPC). A total ... more gate on the compressive strength and elastic modulus of high performance concrete (HPC). A total of 60 cubes of HPC with 0.25 w/b ratio, 28-day target cube strength of 80 MPa using the British Design Method were cast and cured in water for 3, 7, 21 and 28 days. Three variants of gregate samples, with two coarse aggregate sizes (6mm and 13mm maximum) used. The results
West African Built Environment Conference (WABER 2012), Abuja, Nigeria, Jul 19, 2012
This study investigates effect of calcination on oxide composition of Volcanic Ash (VA) sample ob... more This study investigates effect of calcination on oxide composition of Volcanic Ash (VA) sample obtained from Dutsin Dushowa, Kerang in Mangu Local Government Area of Plateau State, Nigeria. VA sample was collected as a lump, pounded, grounded, sieved with a 75 µm sieve and calcinated in a furnace at five temperatures levels (i.e. 500, 600
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This paper investigated the effect of batching by mass and volume on concrete's compressive stren... more This paper investigated the effect of batching by mass and volume on concrete's compressive strength and workability. Influence of mix proportion at five levels and various water-cement ratios were also studied. All samples were cured by complete immersion in water and tested up to 28 days. The results indicated higher workabilities for concrete batched by mass than concrete batched by volume at all w/c ratios and mix proportions investigated. The workability increased with increase in w/c ratios in both methods. The compressive strength results showed that for rich structural mixes (1:1:2 and 1:1.5:3), concrete batched by mass had 20 % and 6 % strength increases respectively over the concrete batched by volume. Ordinary structural mix (1:2:4) had 14 % increase while non-structural mixes (1:3:6 and 1:4:8) had 8 % and 6 % increases respectively. In all cases, concrete batched by mass had better fresh and hardened properties of concrete.
Civil Engineering Dimensions, Vol.14 No.2, Sep 2012
This study investigates the influence of curing age and mix proportions on the compressive streng... more This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA) blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm 2 (using British Method) was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT) contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm 2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α 0.5) on the compressive strength of the VA-blended cement laterized concrete.
Construction Focus - Journal of the Dept. of Building, Ahmadu Bello University, Zaria, Nigeria., 2011
This work involved onsite observation of the production process; determination of physical proper... more This work involved onsite observation of the production process; determination of physical properties and chemical composition of the soil sample used for production of Makurdi burnt bricks (MBB). A total of 22 brick specimens, of the MBB was examined in the laboratory for compressive strength, water absorption and abrasion resistance. The results reveal the soil sample as a true laterite having a Silica-Sesquioxide ratio of 1.01, Silica content of 42.95 and clay content of 27.38 and total clay + silt content of 30.78. The Atterberg’s limit test gave the liquid limit as 36.79; plastic limit, 26.11and plastic index, 10.68. Compressive strength was 3.46 N/mm2 and 11.75 N/mm2 for Samples A and B respectively; Average water absorption for Sample B (16.49%) was double that of Sample A (8.58%) while the Abrasion resistance ability of Sample B (33.67%) was four times better than Sample A (9.32%).
West African Built Environment Conference (WABER, 2011), Jul 19, 2011
Lately, research works are being focussed on using renewable agricultural waste resources as cons... more Lately, research works are being focussed on using renewable agricultural waste resources as construction materials. This is to ensure sustainability and to reduce cost of construction. Palm kernel shell concrete (PKSC) is concrete containing cement, sand and palm kernel shells wholly or partially as a coarse aggregate. This paper therefore presents results of an experimental laboratory investigation carried on PKSC by incorporating varying percentages of granite fines to replace sand in steps of 20% to study its effect on the compressive and tensile strength of PKSC. A mix proportion of 1:1.77:0.77 was used with a w/c = 0.50. Calcium Chloride (CaCl 2 ) was added as an accelerator. Results of 28-day strength test using 100 mm cubes and 150 × 300 mm cylinders revealed that the compressive and tensile splitting strengths increased with curing age and with increase in the percent granite fines content. Maximum compressive and tensile splitting strengths were obtained for PKSC containing 100% granite fines. Tensile strength obtained fall within the range of values (1.24-1.90 N/mm 2 ) given for grade 30 concrete.
The Professional Builder - Journal of Nigerian Institute of Building, Mar 2010
Value Engineering (VE) is a management technique widely used in many industries focusing at enhan... more Value Engineering (VE) is a management technique widely used in many industries focusing at enhancing necessary functions reliably at the lowest cost. The emphasis here is removal of unnecessary cost, a concept that can proof very effective in this period of the global economic melt down. This study examines the practice of VE in Nigerian Construction Industry with a view to assess compliance with the generally accepted approaches as identified by Society of American Value Engineers (SAVE). Interviews were conducted with professionals who claimed to have been involved in VE exercise in Lagos and it was noted that the most adopted approaches in practice are modified forms of the Design and/or Construction Audit; The Package Review or a combination of the two and the Contractor's Change Proposal, coming only came as an attempt at cost reduction: Value Engineering Team was not seen in place nor do any exist in Nigeria ). This study hereby offers that the "VE" techniques if properly applied to all construction projects will ensure effective function maximization and removal of unnecessary costs.
The Professional Builder - Journal of the Nigerian Institute if Building, Jul 2009
The practice of value engineering is known to enhance the provision of necessary functions reliab... more The practice of value engineering is known to enhance the provision of necessary functions reliably at the lowest cost; an act that should enhance effectiveness in Nigerian Construction Industry if properly and widely adopted. This paper appraised the concept of value engineering and sought to ascertain its level of popularity as a management technique amongst the professionals in Nigerian Construction Industry. Data was collected through the use of 30 randomly distributed questionnaires, of which 23(76.7%) were received back and analysed. The study revealed that the term "Value Engineering" is not very popular amongst Nigerian construction professionals, although the concept was observed to be incorporated in the cost control and reduction approaches being adopted by some of the professionals. Unhealthy professional practice was seen as a major hindrance to the full-fledge practice of value engineering as a management technique. Proper enlightenment of the professionals and clients of the Industry on the concept through seminars and workshop was thereby recommended while a call is made for an encouragement of the "Contractor's Change Proposal" approach of value engineering with the enactment and implementation of a law backing its practices in Nigeria.
Ife Journal of Environmental Design and Management (Vol. 2, No. 2), Jun 2009
The trend in building materials research is the search for alternatives and in Nigeria like other... more The trend in building materials research is the search for alternatives and in Nigeria like other developing countries the use of plastics in modern construction is being widely adopted as in advance countries. The adoption of polystyrene walling units/panels is fast gaining grounds in Nigeria with variety of approaches been seen around. This study thereby examines polystyrene walling units in comparison with the conventional sandcrete blocks with a view to ascertain its efficiency. A total of 18 numbers of polystyrene walling units were obtained from two different organisations in Abuja adopting different approaches of use (Polystyrene Specimen A (PSA) and Polystyrene Specimen B (PSB)), while nine (9) numbers of sandcrete block units were gotten from a factory in Minna. The samples were cut / prepared to required sizes and then subjected to Laboratory tests to assess their performance level as regards compressive strength, thermal conductivity and fire resistance. The results reflect that PSB has the highest compressive strength value of 3.33N/mm 2 , followed by the sandcrete block with a value of 0.62N/mm 2 while the least compressive strength value is that of PSA giving 0.22N/mm 2 . The thermal conductivity test revealed both PSA and PSB having low values of 0.0047w/mk (for PSB) and 0.0056w/mk (for PSA) as against sandcrete block's value of 0.079w/mk. The fire test further revealed PSA failing at a time of 24.5mins, and 808.5 o C temperature while PSB failed at 15.5mins, a temperature of 743.4 o C, the Sandcrete block (SHB) at 17.0mins, temperature of 757.2 o C as against timber which failed at a time of 4.5mins and a temperature of 561.0 o C. The polystyrene walling units were found to have high resistance to fire; they are poor heat conductors and thereby fit well as alternative walling material. The use should be restricted to partition / curtain walls based on their low compressive strength.
Civil Engineering Dimensions, Vol. 12, No.1 (isbn 1410-9530 print / ISBN 1979-570X online), Mar 2010
This study investigates the effect of partial replacement of cement with volcanic ash (VA) on the... more This study investigates the effect of partial replacement of cement with volcanic ash (VA) on the compressive strength of laterized concrete. A total of 192 cubes of 150mm dimensions were cast and cured in water for 7, 14, 21, and 28 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively, while a control mix of 28-day target strength of 25 N/mm 2 was adopted. The results show that the density and compressive strength of concrete decreased with increase in volcanic ash content. The 28-day, density dropped from 2390 kg/m 3 to 2285 kg/m 3 (i.e. 4.4% loss) and the compressive strength from 25.08 N/mm 2 to 17.98 N/mm 2 (i.e. 28% loss) for 0-30% variation of VA content with no laterite introduced. The compressive strength also decreased with increase in laterite content; the strength of the laterized concrete however increases as the curing age progresses.
Environmental Technology and Science Journal (ETSJ), Vol.3, No.2, 2008
Effect of calcium oxide on volcanic ash laterized concrete was investigated. A total of 60 cubes ... more Effect of calcium oxide on volcanic ash laterized concrete was investigated. A total of 60 cubes of 150mm dimensions were cast with volcanic ash (V.A) and calcium oxide (CaO) combination of 90%:10% and 80%:20% respectively while the ordinary Portland cement (OPC) based concrete for 28-day target strength of 25N/mm 2 served as control. Sand replacement by laterite also varied between 0% and 20% for the laterized specimens. The cubes were cured in water and tested for compressive strength at 7, 14, 21 and 28 days. The result showed that the compressive strength increased as the hydration period increased and that the presence of calcium oxide boosted the strength properties of volcanic ash laterized concrete. The compressive strength of the laterized concrete specimens was higher at the various hydration days for the 20%lat/20%CaO: 80%V.A. sample than the 10%lat/10%CaO: 90%V.A sample. The 28-day strength for 20%lat/20%CaO: 80%V.A sample gave a value of 22.07N/mm 2 (i.e. 81.74%) as against the 21.53N/mm 2 (79.74%) gotten for the 10%lat/10%CaO: 90%V.A. sample, while the control mix gave a 28-day strength value of 27.0N/mm 2 (100%). The volcanic ashlime cement in the laterized concrete specimens therefore reflects good pozzolanic activity and can be adopted for construction of buildings and rural infrastructure.
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Papers by Babatunde J Olawuyi