Frequently Asked Questions

A manufacturer. Hebei Hualing Rubber Co., Ltd. operates a workshop in Wuqiang County, Hengshui, Hebei, with two two-component sealant lines, one rubber waterstop line and two foam board lines. Products are made and sold directly, so engineering buyers deal with the plant.

Sealant from 1 drum, rubber waterstop and water-swelling strip from 50 m, PE closed-cell foam board from 1 m², swelling sealant from 1 carton (20 cartridges). Small trial orders are welcome.

Up to 10 t of sealant ships in 1 day, up to 1,000 m of waterstop in 1 day, up to 10,000 m² of foam board in 1 day (excluding cutting time), and up to 10,000 cartridges of swelling sealant the same day. Nationwide logistics: next day within Hebei, within 4 days elsewhere.

Yes. Every product has been tested by an accredited third-party laboratory and the report can be supplied with the goods. Polysulfide and polyurethane sealants also hold GB/T 17219 hygiene assessment reports for drinking-water contact materials.

We support pre-purchase sampling and third-party re-testing, with a full refund if a test fails.

Yes. Rubber waterstops are made from more than 20 moulds and can be produced to drawing; foam board can be cut to project sizes; sealant modulus and colour can be adjusted; non-standard strip sizes can be made to order.

Yes. We handle export orders by road and sea freight and can provide English technical documentation and packing documents.

Tel +86 13081809758 (Mr Hou), email mifengjiaochang@163.com, workshop at No. 97 Xifantun Village, Wuqiang Town, Wuqiang County, Hengshui, Hebei, China.

Normally A:B = 10:1 by weight; some batches range from 100:8 to 100:12, so follow the datasheet. Weigh on a scale and mix with a power stirrer for 3–5 minutes until the colour is uniform. An inaccurate ratio or poor mixing can leave the sealant permanently soft, or cure it brittle and inelastic; excess B causes reverse vulcanisation and the batch is scrap.

At 25 °C skin formation takes about 2–8 hours (10 hours measured on the batch we tested) and full cure takes 3–7 days. Lower temperature and higher humidity both slow it down. No water, load or rain before cure. Basins and canals must be fully cured before filling, and winter work needs a longer curing period.

The usual ratio is A:B = 10:1 by weight, with error kept within ±1–5%; follow the datasheet. Mix mechanically for 2–5 minutes until uniform with no pale streaks. Too little B leaves the sealant soft and uncured; too much makes it brittle, inelastic and prone to cracking.

At 25 °C skin formation takes about 1–4 hours (5 hours measured on our test batch); after 24 hours it can be touched lightly. Full cure takes about 7 days to reach tensile strength and waterproofing performance, after which it can take traffic, be backfilled and be hydrostatically tested. At around 5 °C in winter the cycle extends to 10–14 days.

One-component is ready to gun straight from the cartridge with no mixing, which suits small joints, patch repairs and fast-turnaround sites. Two-component cures faster and reaches higher strength, which suits large-volume expansion joint sealing. One-component cures on atmospheric moisture, so the bead must not be too thick — apply in layers if deep.

A common cartridge is 600 ml (about 750 g). For a 10 mm × 10 mm joint one cartridge covers roughly 8–10 m; larger joints use more. Estimating formula: kg per metre ≈ width × depth × density (1.1–1.2) ÷ 1000.

Type 651 has a single centre bulb, type 652 has two. 300×8 means 300 mm wide and 8 mm thick — the most common size in practice. Wider options include 350×8, 350×10 and 400×10. Always start from the type and size on the design drawing.

Four points: (1) the centre bulb must align with the joint centre and be fixed with added rebar or dedicated clamps — never nail through it; (2) the waterstop must lie flat, not rolled or twisted; (3) cast half embedded and half exposed, and vibrate thoroughly so concrete beds onto the rubber; (4) keep aggregate and rebar ends from puncturing it, and repair any damage immediately.

Yes. The trade also calls it an external waterstop. This site uses "surface-mounted" consistently to mean a waterstop bonded to the outer, water-facing face of the structure.

Not entirely. The surface-mounted type is bonded to the outside of the structure and serves as an additional sealing line and repair measure; the buried type is cast into the concrete and is the primary barrier. Important works generally use both.

The rubber body is the same; the steel-edge type adds galvanised steel strips on both flanks. The steel interlocks mechanically with the concrete, raising pressure and displacement resistance and holding position more reliably during casting. It costs more than a standard buried waterstop.

The steel edge may be tack-welded, but the rubber must never be welded. Welding heat burns through the rubber and creates a leakage path, so heat protection is essential.

L600 is the high-pressure grade: about 55 Shore A, density about 120–130 kg/m³, black, hard and strong in compression — used in dams and high-pressure hydraulic joints. L1100 is the medium-pressure grade: about 35 Shore A, density about 90 kg/m³, grey, softer with good recovery — used for general joint filling in roads, basins and canals. In short: high load and high pressure → L600; general filling → L1100.

It absorbs almost nothing. Each cell is individually closed, so water cannot penetrate, which is why it stays stable when buried or immersed — the key advantage over bitumen-impregnated wood fibre board. It is however sensitive to UV, so store it out of direct sunlight. Cut or damaged faces expose open cells that can absorb water, so avoid scoring by aggregate or sharp objects.

Putty type is black, soft and self-adhesive — peel and stick, lower cost, used above the water table in secondary locations with low water pressure. Formed type is elastic, resists water pressure and needs a shallow groove for fixing, so it is used in more demanding construction joints. For ordinary basement raft and wall construction joints, putty 20×30 mm is the usual choice.

Three fixing methods: (1) preformed groove — nail a batten to the formwork, strip it and embed the strip; (2) full-length bonding with 401 adhesive; (3) steel pins at 800–1,000 mm on horizontal joints and 600–800 mm on vertical faces, never piercing the body. Butt splices are pressed flat with at least 50 mm overlap.

Putty is cheaper, faster and shapeable — suited to secondary locations above the water table with low pressure. Formed type has better elasticity and pressure resistance — suited to more demanding construction joints. For ordinary basement raft and wall joints, putty 20×30 mm is enough.

No. Swelling is one-way: once expanded it cannot be compressed tight, so it must be peeled off and replaced. Store delivered material under cover, protected from rain and damp.

To JG/T 312-2011, PJ-220 swells 200–400% and PJ-400 more than 400%. Ordinary underground work is served by PJ-220; where leakage risk and pressure are high, choose PJ-400. On acceptance, ask for the test report and check volumetric swelling ratio, bond strength and skin formation time.

Typical underground work uses multiple lines of defence: a waterstop embedded in the movement joint as the primary barrier; a strip or this sealant on the construction joint face as the second; surface-mounted waterstop or coating as the third. The sealant suits construction joints, embedded items and bolt holes; strips suit regular horizontal and vertical joints; movement joints with large displacement and high pressure need a waterstop. They complement rather than replace each other.