Abstract:
Concrete is used extensively in building construction. However, it is susceptible to corrosion, moisture migration, cracking, delamination and spalling is on the increase. These may be mitigated by components reconstitution with the inclusion of non-corrosive reinforcement and water repellent additive. Literature is sparse on the combined use of bamboo (Bambusa vulgaris) and Acrylic Polymer (AP) as means of arresting these deficiencies. This study was therefore, designed to investigate the effects of the inclusion of bamboo and AP on cement blocks, roof tiles and columns.
Portland Limestone Cement (PLC), sand, AP andbamboo culms were obtained locally. The culms were sun-dried to 8% moisture content, processed into 6×10×900mm strips and 2.0mm fibres. The strips and fibres were treated with bitumen (12.0% w/w) and NaOH (10.0% conc.), respectively. Blocks(150×150×150mm) at four bamboo fibre levels(0,0.5,1.0,1.5%)and AP(0,5.0,10.0,15.0%) by mass of cement, roofing tiles (810×910×1520mm)and columns(150×150×900mm)reinforced with bamboo strips and ferrocement mesh were produced in three replicates. Binder:sand ratio of 1:3 was used for blocks and roofing tiles, while binder:fine sand:coarse aggregate ratio of 1:3:3 was used for columns at a constant water/cement ratio of 0.58. A 813×914×1524mmvibration table was developed and used to agitate the roof tiles at a frequency of 1200 rev/mins. All composite samples were cured for 28 days except the blocks which were cured for 28, 45 and 60 days. Block density, water absorption, compressive, flexural, split tensile strength and microstructure arrangement were determined using standard methods. Accelerated ageing using Modulus of Rupture (MOR) and Modulus of Elasticity (MOE) and effects of edge cracks on natural weathering of the roofing tiles were evaluated, while axial deflection tests were performed on the columns. All tests were performed according to ASTM, ACI and BS standards. Data were analysed using descriptive statistics and ANOVA at α0.05.
Block density and water absorption were 1410-1880 kg/m3 and 1.0-2.9%, respectively, while compressive, flexural and split strength were 22.9-29.6 N/mm2; 4.0-9.9 N/mm2 and 3.0-4.9 N/mm2, respectively at 28 days; 26.2-39.2 N/mm2; 6.4-10.9 N/mm2 and 3.5-6.9 N/mm2 at 45 days; 31.9- 44.9 N/mm2; 8.3-11.7 N/mm2 and 4.1-7.7 N/mm2, respectively at 60 days. The best block property was attained at 1.5 % fibre contents and 10.0% AP with density, water absorption, compressive, flexural and split strength of 1410±57 kg/m3, 2.8±0.1%, 44.9±2.6 N/mm2, 12.1±0.9 N/mm2 and 7.7±0.6 N/mm2, respectively. The fibres and polymers created anchorage between the reinforcement and matrix. There was no significant difference in MOR (2.1–2.4 N/mm2) and MOE (457.9–877.6 N/mm2) after accelerated ageing tests. At 1.5% bamboo and 10.0% AP with ferrocement, there was no noticeable edge crack in the roof tiles after 24 months-weather exposure. Column axial deflections reduced from 3.6 to 0.3mm on inclusion of bamboo reinforcement and AP additive.
Reinforcement with bamboo and addition of acrylic polymer enhanced the dimensional stability, strength and durability of concrete blocks, roofing tiles and columns.
