Mechanical Performance of Precast Honeycomb Pavement Using Hybrid Fibre Reinforced Self-Compacting Concrete

Hung Ling, Lim (2022) Mechanical Performance of Precast Honeycomb Pavement Using Hybrid Fibre Reinforced Self-Compacting Concrete. PhD thesis, Universiti Malaysia Sarawak.

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Abstract

Road construction technology has evolved from traditionally asphalt (or bitumen) pavement and cast-in-situ concrete pavement to precast concrete pavement for better road quality, and more rapid construction and rehabilitation. However, these precast concrete pavements are usually constructed from large-sized precast concrete panels which require heavy machinery such as cranes to move and place them at the site. Thus, this research has sought to develop a new precast concrete pavement, “Precast Honeycomb Pavement” (PHP), that is portable and constructible by human strength. To develop an excellent quality portable precast concrete pavement, its precast components also need to be produced from high-performance concrete material. Thus, this research aims to develop high performance hybrid fibre self-compacting (HFSCC) to produce the precast pavement components and test the structural performance of PHP. This research has three experimental phases: 1. developing HFSCC, 2. test the structural performance of PHP’s concrete components, and 3. conduct PHP on-site testing. The HFSCC development has involved several processes of adjusting the mix proportion of newly designed C50 plain self-compacting concrete (NFSCC) before incorporating two types of fibres. NFSCC’s mix design is adjusted to achieve the required fresh properties, which are filling ability, passing ability and segregation resistance, based on EFNARC’s guideline. The NFSCC is then incorporated with fibres to become HFSCC. Subsequently, HFSCC’s water/binder ratio and superplasticizer dosage are readjusted to maintain good flowability and self-compactability. Compared to NFSCC’s mechanical performance, HFSCC has achieved 13.07% higher in 28th Day compressive strength, 1.05% higher in 28th Day tensile, and 32.72% higher in modulus of elasticity. However, a little reduction is found in flexural strength. In testing of PHP’s concrete components’ structural performance, few sets of precast hexagonal slab blocks, precast half slab blocks, cast-in-situ interlocking keys and precast interlocking keys are produced using NFSCC and HFSCC to test and compare their performance against their counterparts’. Although tested load capacities of both NFSCC and HFSCC’s precast hexagonal slab blocks are more than twice of design load 52.0 kN, shear cracks have appeared in NFSCC’s slab blocks while HFSCC’s slab blocks have no crack. HFSCC’s precast hexagonal slab block’s bottom ring has achieved a higher ultimate shear capacity than NFSCC’s. Precast interlocking keys are capable of achieving the required shear capacity in a shorter time than cast-in-situ interlocking keys. HFSCC’s precast interlocking key also has shown better shear resistance than NFSCC’s. In PHP’s on-site testing, mass-produced PHP’s precast components are assembled into 10.250 metres length, 3.964 metres width of PHP at a provided test site by hired labours. The performance of PHP under vehicle loading such as pavement settlement and technical status of precast components is monitored for a half year. Monolithic pavement settlement at a field testing site is observed in first month of testing before precast interlocking keys are broken over time. At the 6th month of site testing, 7.45% of precast hexagonal top slab blocks have shear cracks. Hence, NFSCC’s precast components are found that have poor service life under actual vehicle loading. In a nutshell, precast concrete pavement can be assembled without the aid of heavy machinery. However, PHP needs to be produced using HFSCC to perform better under actual vehicle loading.

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